From b8e42a651bdee06202ebdd96cff64fdeabd5b1d6 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 4 Jun 2020 10:48:19 +0200 Subject: ovl: get rid of redundant members in struct ovl_fs ofs->upper_mnt is copied to ->layers[0].mnt and ->layers[0].trap could be used instead of a separate ->upperdir_trap. Split the lowerdir option early to get the number of layers, then allocate the ->layers array, and finally fill the upper and lower layers, as before. Get rid of path_put_init() in ovl_lower_dir(), since the only caller will take care of that. [Colin Ian King] Fix null pointer dereference on null stack pointer on error return found by Coverity. Signed-off-by: Miklos Szeredi --- fs/overlayfs/ovl_entry.h | 4 +- fs/overlayfs/super.c | 99 +++++++++++++++++++++++------------------------- 2 files changed, 48 insertions(+), 55 deletions(-) diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h index 2da0ff355824..b429c80879ee 100644 --- a/fs/overlayfs/ovl_entry.h +++ b/fs/overlayfs/ovl_entry.h @@ -46,7 +46,6 @@ struct ovl_path { /* private information held for overlayfs's superblock */ struct ovl_fs { - struct vfsmount *upper_mnt; unsigned int numlayer; /* Number of unique fs among layers including upper fs */ unsigned int numfs; @@ -70,7 +69,6 @@ struct ovl_fs { bool workdir_locked; bool share_whiteout; /* Traps in ovl inode cache */ - struct inode *upperdir_trap; struct inode *workbasedir_trap; struct inode *workdir_trap; struct inode *indexdir_trap; @@ -84,7 +82,7 @@ struct ovl_fs { static inline struct vfsmount *ovl_upper_mnt(struct ovl_fs *ofs) { - return ofs->upper_mnt; + return ofs->layers[0].mnt; } static inline struct ovl_fs *OVL_FS(struct super_block *sb) diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 201be5024494..eb81d8760a6a 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -216,7 +216,6 @@ static void ovl_free_fs(struct ovl_fs *ofs) iput(ofs->workbasedir_trap); iput(ofs->indexdir_trap); iput(ofs->workdir_trap); - iput(ofs->upperdir_trap); dput(ofs->whiteout); dput(ofs->indexdir); dput(ofs->workdir); @@ -225,8 +224,7 @@ static void ovl_free_fs(struct ovl_fs *ofs) dput(ofs->workbasedir); if (ofs->upperdir_locked) ovl_inuse_unlock(ovl_upper_mnt(ofs)->mnt_root); - mntput(ofs->upper_mnt); - for (i = 1; i < ofs->numlayer; i++) { + for (i = 0; i < ofs->numlayer; i++) { iput(ofs->layers[i].trap); mntput(ofs->layers[i].mnt); } @@ -837,11 +835,11 @@ static int ovl_lower_dir(const char *name, struct path *path, err = ovl_mount_dir_noesc(name, path); if (err) - goto out; + return err; err = ovl_check_namelen(path, ofs, name); if (err) - goto out_put; + return err; *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth); @@ -863,11 +861,6 @@ static int ovl_lower_dir(const char *name, struct path *path, ofs->xino_mode = -1; return 0; - -out_put: - path_put_init(path); -out: - return err; } /* Workdir should not be subdir of upperdir and vice versa */ @@ -1074,7 +1067,7 @@ static int ovl_report_in_use(struct ovl_fs *ofs, const char *name) } static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs, - struct path *upperpath) + struct ovl_layer *upper_layer, struct path *upperpath) { struct vfsmount *upper_mnt; int err; @@ -1094,7 +1087,7 @@ static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs, if (err) goto out; - err = ovl_setup_trap(sb, upperpath->dentry, &ofs->upperdir_trap, + err = ovl_setup_trap(sb, upperpath->dentry, &upper_layer->trap, "upperdir"); if (err) goto out; @@ -1108,7 +1101,9 @@ static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs, /* Don't inherit atime flags */ upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME); - ofs->upper_mnt = upper_mnt; + upper_layer->mnt = upper_mnt; + upper_layer->idx = 0; + upper_layer->fsid = 0; /* * Inherit SB_NOSEC flag from upperdir. @@ -1458,18 +1453,13 @@ static int ovl_get_fsid(struct ovl_fs *ofs, const struct path *path) } static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, - struct path *stack, unsigned int numlower) + struct path *stack, unsigned int numlower, + struct ovl_layer *layers) { int err; unsigned int i; - struct ovl_layer *layers; err = -ENOMEM; - layers = kcalloc(numlower + 1, sizeof(struct ovl_layer), GFP_KERNEL); - if (!layers) - goto out; - ofs->layers = layers; - ofs->fs = kcalloc(numlower + 1, sizeof(struct ovl_sb), GFP_KERNEL); if (ofs->fs == NULL) goto out; @@ -1477,11 +1467,6 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, /* idx/fsid 0 are reserved for upper fs even with lower only overlay */ ofs->numfs++; - layers[0].mnt = ovl_upper_mnt(ofs); - layers[0].idx = 0; - layers[0].fsid = 0; - ofs->numlayer = 1; - /* * All lower layers that share the same fs as upper layer, use the same * pseudo_dev as upper layer. Allocate fs[0].pseudo_dev even for lower @@ -1579,44 +1564,30 @@ out: } static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb, - struct ovl_fs *ofs) + const char *lower, unsigned int numlower, + struct ovl_fs *ofs, struct ovl_layer *layers) { int err; - char *lowertmp, *lower; struct path *stack = NULL; - unsigned int stacklen, numlower = 0, i; + unsigned int i; struct ovl_entry *oe; - err = -ENOMEM; - lowertmp = kstrdup(ofs->config.lowerdir, GFP_KERNEL); - if (!lowertmp) - goto out_err; - - err = -EINVAL; - stacklen = ovl_split_lowerdirs(lowertmp); - if (stacklen > OVL_MAX_STACK) { - pr_err("too many lower directories, limit is %d\n", - OVL_MAX_STACK); - goto out_err; - } else if (!ofs->config.upperdir && stacklen == 1) { + if (!ofs->config.upperdir && numlower == 1) { pr_err("at least 2 lowerdir are needed while upperdir nonexistent\n"); - goto out_err; + return ERR_PTR(-EINVAL); } else if (!ofs->config.upperdir && ofs->config.nfs_export && ofs->config.redirect_follow) { pr_warn("NFS export requires \"redirect_dir=nofollow\" on non-upper mount, falling back to nfs_export=off.\n"); ofs->config.nfs_export = false; } - err = -ENOMEM; - stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL); + stack = kcalloc(numlower, sizeof(struct path), GFP_KERNEL); if (!stack) - goto out_err; + return ERR_PTR(-ENOMEM); err = -EINVAL; - lower = lowertmp; - for (numlower = 0; numlower < stacklen; numlower++) { - err = ovl_lower_dir(lower, &stack[numlower], ofs, - &sb->s_stack_depth); + for (i = 0; i < numlower; i++) { + err = ovl_lower_dir(lower, &stack[i], ofs, &sb->s_stack_depth); if (err) goto out_err; @@ -1630,7 +1601,7 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb, goto out_err; } - err = ovl_get_layers(sb, ofs, stack, numlower); + err = ovl_get_layers(sb, ofs, stack, numlower, layers); if (err) goto out_err; @@ -1648,7 +1619,6 @@ out: for (i = 0; i < numlower; i++) path_put(&stack[i]); kfree(stack); - kfree(lowertmp); return oe; @@ -1772,7 +1742,10 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) struct dentry *root_dentry; struct ovl_entry *oe; struct ovl_fs *ofs; + struct ovl_layer *layers; struct cred *cred; + char *splitlower = NULL; + unsigned int numlower; int err; sb->s_d_op = &ovl_dentry_operations; @@ -1804,6 +1777,26 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) goto out_err; } + err = -ENOMEM; + splitlower = kstrdup(ofs->config.lowerdir, GFP_KERNEL); + if (!splitlower) + goto out_err; + + numlower = ovl_split_lowerdirs(splitlower); + if (numlower > OVL_MAX_STACK) { + pr_err("too many lower directories, limit is %d\n", + OVL_MAX_STACK); + goto out_err; + } + + layers = kcalloc(numlower + 1, sizeof(struct ovl_layer), GFP_KERNEL); + if (!layers) + goto out_err; + + ofs->layers = layers; + /* Layer 0 is reserved for upper even if there's no upper */ + ofs->numlayer = 1; + sb->s_stack_depth = 0; sb->s_maxbytes = MAX_LFS_FILESIZE; atomic_long_set(&ofs->last_ino, 1); @@ -1825,7 +1818,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) goto out_err; } - err = ovl_get_upper(sb, ofs, &upperpath); + err = ovl_get_upper(sb, ofs, &layers[0], &upperpath); if (err) goto out_err; @@ -1840,7 +1833,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) sb->s_time_gran = ovl_upper_mnt(ofs)->mnt_sb->s_time_gran; } - oe = ovl_get_lowerstack(sb, ofs); + oe = ovl_get_lowerstack(sb, splitlower, numlower, ofs, layers); err = PTR_ERR(oe); if (IS_ERR(oe)) goto out_err; @@ -1903,6 +1896,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) goto out_free_oe; mntput(upperpath.mnt); + kfree(splitlower); sb->s_root = root_dentry; @@ -1912,6 +1906,7 @@ out_free_oe: ovl_entry_stack_free(oe); kfree(oe); out_err: + kfree(splitlower); path_put(&upperpath); ovl_free_fs(ofs); out: -- cgit v1.2.3