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path: root/drivers/tty/vt/vt.c
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2020-11-08vt: Disable KD_FONT_OP_COPYDaniel Vetter
It's buggy: On Fri, Nov 06, 2020 at 10:30:08PM +0800, Minh Yuan wrote: > We recently discovered a slab-out-of-bounds read in fbcon in the latest > kernel ( v5.10-rc2 for now ). The root cause of this vulnerability is that > "fbcon_do_set_font" did not handle "vc->vc_font.data" and > "vc->vc_font.height" correctly, and the patch > <https://lkml.org/lkml/2020/9/27/223> for VT_RESIZEX can't handle this > issue. > > Specifically, we use KD_FONT_OP_SET to set a small font.data for tty6, and > use KD_FONT_OP_SET again to set a large font.height for tty1. After that, > we use KD_FONT_OP_COPY to assign tty6's vc_font.data to tty1's vc_font.data > in "fbcon_do_set_font", while tty1 retains the original larger > height. Obviously, this will cause an out-of-bounds read, because we can > access a smaller vc_font.data with a larger vc_font.height. Further there was only one user ever. - Android's loadfont, busybox and console-tools only ever use OP_GET and OP_SET - fbset documentation only mentions the kernel cmdline font: option, not anything else. - systemd used OP_COPY before release 232 published in Nov 2016 Now unfortunately the crucial report seems to have gone down with gmane, and the commit message doesn't say much. But the pull request hints at OP_COPY being broken https://github.com/systemd/systemd/pull/3651 So in other words, this never worked, and the only project which foolishly every tried to use it, realized that rather quickly too. Instead of trying to fix security issues here on dead code by adding missing checks, fix the entire thing by removing the functionality. Note that systemd code using the OP_COPY function ignored the return value, so it doesn't matter what we're doing here really - just in case a lone server somewhere happens to be extremely unlucky and running an affected old version of systemd. The relevant code from font_copy_to_all_vcs() in systemd was: /* copy font from active VT, where the font was uploaded to */ cfo.op = KD_FONT_OP_COPY; cfo.height = vcs.v_active-1; /* tty1 == index 0 */ (void) ioctl(vcfd, KDFONTOP, &cfo); Note this just disables the ioctl, garbage collecting the now unused callbacks is left for -next. v2: Tetsuo found the old mail, which allowed me to find it on another archive. Add the link too. Acked-by: Peilin Ye <yepeilin.cs@gmail.com> Reported-by: Minh Yuan <yuanmingbuaa@gmail.com> References: https://lists.freedesktop.org/archives/systemd-devel/2016-June/036935.html References: https://github.com/systemd/systemd/pull/3651 Cc: Greg KH <greg@kroah.com> Cc: Peilin Ye <yepeilin.cs@gmail.com> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: https://lore.kernel.org/r/20201108153806.3140315-1-daniel.vetter@ffwll.ch Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-08-31Merge 5.9-rc3 into tty-nextGreg Kroah-Hartman
We need the tty/serial fixes in here as well. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-08-26Merge tag 'tty-5.9-rc3' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty Pull tty/serial fixes from Greg KH: "Here are a few small TTY/Serial/vt fixes for 5.9-rc3 Included in here are: - qcom serial fixes - vt ioctl and core bugfixes - pl011 serial driver fixes - 8250 serial driver fixes - other misc serial driver fixes and for good measure: - fbcon fix for syzbot found problem. All of these have been in linux-next for a while with no reported issues" * tag 'tty-5.9-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: tty: serial: imx: add dependence and build for earlycon serial: samsung: Removes the IRQ not found warning serial: 8250: change lock order in serial8250_do_startup() serial: stm32: avoid kernel warning on absence of optional IRQ serial: pl011: Fix oops on -EPROBE_DEFER serial: pl011: Don't leak amba_ports entry on driver register error serial: 8250_exar: Fix number of ports for Commtech PCIe cards tty: serial: qcom_geni_serial: Drop __init from qcom_geni_console_setup serial: qcom_geni_serial: Fix recent kdb hang vt_ioctl: change VT_RESIZEX ioctl to check for error return from vc_resize() fbcon: prevent user font height or width change from causing potential out-of-bounds access vt: defer kfree() of vc_screenbuf in vc_do_resize()
2020-08-23treewide: Use fallthrough pseudo-keywordGustavo A. R. Silva
Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary fall-through markings when it is the case. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
2020-08-18tty: vt, fix kernel-docJiri Slaby
As in the previous patches, fix kernel-doc in vt. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200818085655.12071-6-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-08-18vc: propagate "viewed as bool" from screenpos upJiri Slaby
viewed is used as a flag, i.e. bool. So treat is as such in most of the places. vcs_vc is handled in the next patch. Note: the last parameter of invert_screen was misnamed in the declaration since 1.1.92. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200818085706.12163-3-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-08-18vt: declare xy for get/putconsxy properlyJiri Slaby
That is: 1) call the parameter 'xy' to denote what it really is, not generic 'p' 2) tell the compiler and users that we expect an array: * with at least 2 chars (static 2) * which we don't modify in putconsxy (const) Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200818085706.12163-2-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-08-18vt: make vc_data pointers const in selection.hJiri Slaby
There are many functions declared in selection.h which only read from struct vc_data passed as a parameter. Make all those uses const to hint the compiler a bit. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200818085706.12163-1-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-08-18vt: defer kfree() of vc_screenbuf in vc_do_resize()Tetsuo Handa
syzbot is reporting UAF bug in set_origin() from vc_do_resize() [1], for vc_do_resize() calls kfree(vc->vc_screenbuf) before calling set_origin(). Unfortunately, in set_origin(), vc->vc_sw->con_set_origin() might access vc->vc_pos when scroll is involved in order to manipulate cursor, but vc->vc_pos refers already released vc->vc_screenbuf until vc->vc_pos gets updated based on the result of vc->vc_sw->con_set_origin(). Preserving old buffer and tolerating outdated vc members until set_origin() completes would be easier than preventing vc->vc_sw->con_set_origin() from accessing outdated vc members. [1] https://syzkaller.appspot.com/bug?id=6649da2081e2ebdc65c0642c214b27fe91099db3 Reported-by: syzbot <syzbot+9116ecc1978ca3a12f43@syzkaller.appspotmail.com> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: stable <stable@vger.kernel.org> Link: https://lore.kernel.org/r/1596034621-4714-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-27Merge 5.8-rc7 into tty-nextGreg Kroah-Hartman
we need the tty/serial fixes in here as well. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-21tty: vt: Replace HTTP links with HTTPS onesAlexander A. Klimov
Rationale: Reduces attack surface on kernel devs opening the links for MITM as HTTPS traffic is much harder to manipulate. Deterministic algorithm: For each file: If not .svg: For each line: If doesn't contain `\bxmlns\b`: For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`: If neither `\bgnu\.org/license`, nor `\bmozilla\.org/MPL\b`: If both the HTTP and HTTPS versions return 200 OK and serve the same content: Replace HTTP with HTTPS. Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de> Link: https://lore.kernel.org/r/20200718133452.24290-1-grandmaster@al2klimov.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-21vt: Reject zero-sized screen buffer size.Tetsuo Handa
syzbot is reporting general protection fault in do_con_write() [1] caused by vc->vc_screenbuf == ZERO_SIZE_PTR caused by vc->vc_screenbuf_size == 0 caused by vc->vc_cols == vc->vc_rows == vc->vc_size_row == 0 caused by fb_set_var() from ioctl(FBIOPUT_VSCREENINFO) on /dev/fb0 , for gotoxy(vc, 0, 0) from reset_terminal() from vc_init() from vc_allocate() from con_install() from tty_init_dev() from tty_open() on such console causes vc->vc_pos == 0x10000000e due to ((unsigned long) ZERO_SIZE_PTR) + -1U * 0 + (-1U << 1). I don't think that a console with 0 column or 0 row makes sense. And it seems that vc_do_resize() does not intend to allow resizing a console to 0 column or 0 row due to new_cols = (cols ? cols : vc->vc_cols); new_rows = (lines ? lines : vc->vc_rows); exception. Theoretically, cols and rows can be any range as long as 0 < cols * rows * 2 <= KMALLOC_MAX_SIZE is satisfied (e.g. cols == 1048576 && rows == 2 is possible) because of vc->vc_size_row = vc->vc_cols << 1; vc->vc_screenbuf_size = vc->vc_rows * vc->vc_size_row; in visual_init() and kzalloc(vc->vc_screenbuf_size) in vc_allocate(). Since we can detect cols == 0 or rows == 0 via screenbuf_size = 0 in visual_init(), we can reject kzalloc(0). Then, vc_allocate() will return an error, and con_write() will not be called on a console with 0 column or 0 row. We need to make sure that integer overflow in visual_init() won't happen. Since vc_do_resize() restricts cols <= 32767 and rows <= 32767, applying 1 <= cols <= 32767 and 1 <= rows <= 32767 restrictions to vc_allocate() will be practically fine. This patch does not touch con_init(), for returning -EINVAL there does not help when we are not returning -ENOMEM. [1] https://syzkaller.appspot.com/bug?extid=017265e8553724e514e8 Reported-and-tested-by: syzbot <syzbot+017265e8553724e514e8@syzkaller.appspotmail.com> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: stable <stable@vger.kernel.org> Link: https://lore.kernel.org/r/20200712111013.11881-1-penguin-kernel@I-love.SAKURA.ne.jp Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: simplify noncolor attributes in build_attrJiri Slaby
All the attributes are bools, so do a simple shift instead of tests and constants as bool is either 0 or 1. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-28-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: remove superfluous parens in invert_screen and build_attrJiri Slaby
There were too many parentheses in invert_screen, remove them and align the code in invert_screen a bit. No functional change intended. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-27-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: use newly defined CUR_* macrosJiri Slaby
We defined macros for all the magic constants in the previous patch. So let us use the macro in the code now. No functional change intended. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Thomas Winischhofer <thomas@winischhofer.net> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Helge Deller <deller@gmx.de> Cc: linux-usb@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linux-fbdev@vger.kernel.org Cc: linux-parisc@vger.kernel.org Acked-by: Helge Deller <deller@gmx.de> Link: https://lore.kernel.org/r/20200615074910.19267-26-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: redefine world of cursor macrosJiri Slaby
The cursor code used to use magic constants, ANDs, ORs, and some macros. Redefine all this to make some sense. In particular: * Drop CUR_DEFAULT, which is CUR_UNDERLINE. CUR_DEFAULT was used only for cur_default variable initialization, so use CUR_UNDERLINE there to make obvious what's the default. * Drop CUR_HWMASK. Instead, define CUR_SIZE() which explains it more. And use it all over the places. * Define few more masks and bits which will be used in next patches instead of magic constants. * Define CUR_MAKE to build up cursor value. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Cc: dri-devel@lists.freedesktop.org Cc: linux-fbdev@vger.kernel.org Link: https://lore.kernel.org/r/20200615074910.19267-25-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: whitespace and paren cleanup in add_softcursorJiri Slaby
Format add_softcursor according to CodingStyle. Until now, it was a mess of letters. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-24-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: synchronize types and use min in csi_XJiri Slaby
All the types are unsinged ints -- even the vpar passed to the function. So unify them and use min() to compute count instead of explicit comparison. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-23-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: make tc write more obvious in vc_con_write_normalJiri Slaby
Nested ternary operators spread over 4 lines are really evil for reading. Turn the outer one to proper 'if'. Now, we see, there is a common path, so the code can be simplified. This way, the code is understandable now. Checked using symbolic execution (klee), that the old and new behaviors are the same. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-22-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: simplify vc_attr handling in vc_con_write_normalJiri Slaby
Invert the attribute on the only place, without the need of checking 'inverse'. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-21-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vc: simplify condition in vc_con_write_normalJiri Slaby
Convert (!(A && !B) || C) into (!A || B || C) to improve readability. No functional changes, as was just proven by objdump. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-20-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vc: move normal char processing from do_con_writeJiri Slaby
vc_con_write_normal now handles the complex normal characters processing. It is no longer a part of do_con_write. So this patch makes do_con_write pretty clean and obvious. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-19-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vc: extract detecting control characters from do_con_writeJiri Slaby
Move the control characters detection to a separate function dubbed vc_is_control. It makes the 14 subexpressions a "bit" more readable. And also simplifies next patches. It moves also CTRL_ACTION and CTRL_ALWAYS to this new function, as they are used exclusively here. While at it, these are converted to static const variables. And we use "& BIT()" instead of ">>" and "& 1". Checked using symbolic execution (klee), that the old and new behaviors are the same. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-18-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vc: introduce struct vc_draw_regionJiri Slaby
For passing of draw area among functions. This makes next patches simpler. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-17-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vc: move translation out of do_con_writeJiri Slaby
Now that we reordered the code and the label, we can eliminate the translation into a separate function. We call it vc_translate here. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-16-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: move rescan_last_byte label earlierJiri Slaby
This removes duplicated initialization of variables (after reordering 'c' initialization). It will also allow for eliminating whole translation into a separate function in the next patch. Note that vc_state, vc_utf etc. are checked with every rescan now. But they are immutable for non-control characters where rescan might be only necessary. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-15-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: extract attribute inversion to vc_invert_attrJiri Slaby
We continue cleaning up do_con_write. This (hopefully) makes the inversion code obvious. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-14-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: rearrange vc_translate_unicodeJiri Slaby
The code was too overcomplicated. Extract vc_sanitize_unicode to a separate function and flatten the code. I believe the code is straightforward now. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-13-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: separate unicode handling into vc_translate_unicodeJiri Slaby
do_con_write is complicated enough. Extract unicode handling to a separate function. For do_con_write, 249 LOCs lowered to 183 lines. Use diff -w -b to see the difference is neligible -- mostly whitespace and use of 'return's instead of 'continue's. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-12-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: use modern types in do_con_writeJiri Slaby
Use bools for rescan and inverse. And true/false accordingly. Use u8 for width instead of uint8_t. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-11-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: move vc_translate to vt.c and rename itJiri Slaby
vc_translate is used only in vt.c, so move the definition from a header there. Also, it used to be a macro, so be modern and make a static inline from it. This makes the code actually readable. And as a preparation for next patches, rename it to vc_translate_ascii. vc_translate will be a wrapper for both unicode and this one. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-10-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: get rid of VT10.ID macrosJiri Slaby
VT100ID is unused, but defined twice. Kill it. VT102ID is used only in respond_ID. Define there a variable with proper type and use that instead. Then drop both defines of VT102ID too. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-9-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: use tty_insert_flip_string in respond_stringJiri Slaby
Pass the length of a string to respond_string and use tty_insert_flip_string instead of a loop with tty_insert_flip_char. This simplifies the processing on the tty side. The added strlens are optimized during constant folding and propagation and the result are proper constants in assembly. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-8-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: convert vc_tab_stop to bitmapJiri Slaby
vc_tab_stop is used as a bitmap, but defined as an unsigned int array. Switch it to bitmap and convert all users to the bitmap interface. Note the difference in behavior! We no longer mask the top 24 bits away from x, hence we do not wrap tabs at 256th column. Instead, we silently drop attempts to set a tab behind 256 columns. And we will also seek by '\t' to the rightmost column, when behind that boundary. I do not think the original behavior was desired and that someone relies on that. If this turns out to be the case, we can change the added 'if's back to masks here and there instead... (Or we can increase the limit as fb consoles now have 240 chars here. And they could have more with higher than my resolution, of course.) Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-6-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: switch G0/1_charset to an arrayJiri Slaby
Declare Gx_charset[2] instead of G0_charset and G1_charset. It makes the code simpler (without ternary operators). Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-5-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: deduplicate setGx codeJiri Slaby
The code for setting G0 and G1 is duplicated -- for each of them. Move the code to a separate function (vc_setGx) and distinguish the two cases by a parameter. Change if-else-if to switch which allows for slightly better optimization (decision tree). Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-4-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vc: switch state to boolJiri Slaby
The code currently uses bitfields to store true-false values. Switch all of that to bools. Apart from the cleanup, it saves 20B of code as many shifts, ANDs, and ORs became simple movzb's. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-3-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vt: introduce enum vc_intensity for intensityJiri Slaby
Introduce names (en enum) for 0, 1, and 2 constants. We now have VCI_HALF_BRIGHT, VCI_NORMAL, and VCI_BOLD instead. Apart from the cleanup, 1) the enum allows for better type checking, and 2) this saves some code. No more fiddling with bits is needed in assembly now. (OTOH, the structure is larger.) Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-2-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24vc: separate stateJiri Slaby
There are two copies of some members of struct vc_data. This is because we need to save them and restore later. Move these memebers to a separate structure called vc_state. So now instead of members like: vc_x, vc_y and vc_saved_x, vc_saved_y we have state and saved_state (of type: struct vc_state) containing state.x, state.y and saved_state.x, saved_state.y This change: * makes clear what is saved & restored * eases save & restore by using memcpy (see save_cur and restore_cur) Finally, we document the newly added struct vc_state using kernel-doc. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200615074910.19267-1-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-05-04vt: fix unicode console freeing with a common interfaceNicolas Pitre
By directly using kfree() in different places we risk missing one if it is switched to using vfree(), especially if the corresponding vmalloc() is hidden away within a common abstraction. Oh wait, that's exactly what happened here. So let's fix this by creating a common abstraction for the free case as well. Signed-off-by: Nicolas Pitre <nico@fluxnic.net> Reported-by: syzbot+0bfda3ade1ee9288a1be@syzkaller.appspotmail.com Fixes: 9a98e7a80f95 ("vt: don't use kmalloc() for the unicode screen buffer") Cc: <stable@vger.kernel.org> Reviewed-by: Sam Ravnborg <sam@ravnborg.org> Link: https://lore.kernel.org/r/nycvar.YSQ.7.76.2005021043110.2671@knanqh.ubzr Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-04-23vt: don't hardcode the mem allocation upper boundNicolas Pitre
The code in vc_do_resize() bounds the memory allocation size to avoid exceeding MAX_ORDER down the kzalloc() call chain and generating a runtime warning triggerable from user space. However, not only is it unwise to use a literal value here, but MAX_ORDER may also be configurable based on CONFIG_FORCE_MAX_ZONEORDER. Let's use KMALLOC_MAX_SIZE instead. Note that prior commit bb1107f7c605 ("mm, slab: make sure that KMALLOC_MAX_SIZE will fit into MAX_ORDER") the KMALLOC_MAX_SIZE value could not be relied upon. Signed-off-by: Nicolas Pitre <nico@fluxnic.net> Cc: <stable@vger.kernel.org> # v4.10+ Link: https://lore.kernel.org/r/nycvar.YSQ.7.76.2003281702410.2671@knanqh.ubzr Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-04-23vt: don't use kmalloc() for the unicode screen bufferNicolas Pitre
Even if the actual screen size is bounded in vc_do_resize(), the unicode buffer is still a little more than twice the size of the glyph buffer and may exceed MAX_ORDER down the kmalloc() path. This can be triggered from user space. Since there is no point having a physically contiguous buffer here, let's avoid the above issue as well as reducing pressure on high order allocations by using vmalloc() instead. Signed-off-by: Nicolas Pitre <nico@fluxnic.net> Cc: <stable@vger.kernel.org> Acked-by: Sam Ravnborg <sam@ravnborg.org> Link: https://lore.kernel.org/r/nycvar.YSQ.7.76.2003282214210.2671@knanqh.ubzr Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-27vt: vt_ioctl: fix VT_DISALLOCATE freeing in-use virtual consoleEric Biggers
The VT_DISALLOCATE ioctl can free a virtual console while tty_release() is still running, causing a use-after-free in con_shutdown(). This occurs because VT_DISALLOCATE considers a virtual console's 'struct vc_data' to be unused as soon as the corresponding tty's refcount hits 0. But actually it may be still being closed. Fix this by making vc_data be reference-counted via the embedded 'struct tty_port'. A newly allocated virtual console has refcount 1. Opening it for the first time increments the refcount to 2. Closing it for the last time decrements the refcount (in tty_operations::cleanup() so that it happens late enough), as does VT_DISALLOCATE. Reproducer: #include <fcntl.h> #include <linux/vt.h> #include <sys/ioctl.h> #include <unistd.h> int main() { if (fork()) { for (;;) close(open("/dev/tty5", O_RDWR)); } else { int fd = open("/dev/tty10", O_RDWR); for (;;) ioctl(fd, VT_DISALLOCATE, 5); } } KASAN report: BUG: KASAN: use-after-free in con_shutdown+0x76/0x80 drivers/tty/vt/vt.c:3278 Write of size 8 at addr ffff88806a4ec108 by task syz_vt/129 CPU: 0 PID: 129 Comm: syz_vt Not tainted 5.6.0-rc2 #11 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20191223_100556-anatol 04/01/2014 Call Trace: [...] con_shutdown+0x76/0x80 drivers/tty/vt/vt.c:3278 release_tty+0xa8/0x410 drivers/tty/tty_io.c:1514 tty_release_struct+0x34/0x50 drivers/tty/tty_io.c:1629 tty_release+0x984/0xed0 drivers/tty/tty_io.c:1789 [...] Allocated by task 129: [...] kzalloc include/linux/slab.h:669 [inline] vc_allocate drivers/tty/vt/vt.c:1085 [inline] vc_allocate+0x1ac/0x680 drivers/tty/vt/vt.c:1066 con_install+0x4d/0x3f0 drivers/tty/vt/vt.c:3229 tty_driver_install_tty drivers/tty/tty_io.c:1228 [inline] tty_init_dev+0x94/0x350 drivers/tty/tty_io.c:1341 tty_open_by_driver drivers/tty/tty_io.c:1987 [inline] tty_open+0x3ca/0xb30 drivers/tty/tty_io.c:2035 [...] Freed by task 130: [...] kfree+0xbf/0x1e0 mm/slab.c:3757 vt_disallocate drivers/tty/vt/vt_ioctl.c:300 [inline] vt_ioctl+0x16dc/0x1e30 drivers/tty/vt/vt_ioctl.c:818 tty_ioctl+0x9db/0x11b0 drivers/tty/tty_io.c:2660 [...] Fixes: 4001d7b7fc27 ("vt: push down the tty lock so we can see what is left to tackle") Cc: <stable@vger.kernel.org> # v3.4+ Reported-by: syzbot+522643ab5729b0421998@syzkaller.appspotmail.com Acked-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Eric Biggers <ebiggers@google.com> Link: https://lore.kernel.org/r/20200322034305.210082-2-ebiggers@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-16vt: indent switch-case in setterm_command properlyJiri Slaby
Shift cases one level left. This makes the code more readable and some lines need not wrap anymore. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200316065911.11024-3-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-16vt: use min() to limit intervalsJiri Slaby
Instead of awkward ternary operator with comparison, use simple min() for blankinterval and vesa_off_interval. No functional change intended and "objdump -d" proves that. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200316065911.11024-1-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-12vt: drop redundant might_sleep() in do_con_write()Eric Biggers
The might_sleep() in do_con_write() is redundant because console_lock() already contains might_sleep(). Remove it. Signed-off-by: Eric Biggers <ebiggers@google.com> Link: https://lore.kernel.org/r/20200224073450.292892-1-ebiggers@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-10Merge 5.6-rc5 into tty-nextGreg Kroah-Hartman
We need the vt fixes in here and it resolves a merge issue with drivers/tty/vt/selection.c Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-02-28vt: selection, push console lock downJiri Slaby
We need to nest the console lock in sel_lock, so we have to push it down a bit. Fortunately, the callers of set_selection_* just lock the console lock around the function call. So moving it down is easy. In the next patch, we switch the order. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Fixes: 07e6124a1a46 ("vt: selection, close sel_buffer race") Cc: stable <stable@vger.kernel.org> Link: https://lore.kernel.org/r/20200228115406.5735-1-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-02-24Merge 5.6-rc3 into tty-nextGreg Kroah-Hartman
We want the tty fixes in here as well. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-02-21vt: selection, introduce vc_is_selJiri Slaby
Avoid global variables (namely sel_cons) by introducing vc_is_sel. It checks whether the parameter is the current selection console. This will help putting sel_cons to a struct later. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20200219073951.16151-1-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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