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author | Yonghong Song <yhs@fb.com> | 2020-05-09 10:59:15 -0700 |
---|---|---|
committer | Alexei Starovoitov <ast@kernel.org> | 2020-05-09 17:05:27 -0700 |
commit | 1d68f22b3d53d368d5cc8d09de890250cae5c945 (patch) | |
tree | a334f400fd965545b5309cdebe477566ac32d30e /tools/lib/bpf | |
parent | 492e639f0c222784e2e0f121966375f641c61b15 (diff) |
bpf: Handle spilled PTR_TO_BTF_ID properly when checking stack_boundary
This specifically to handle the case like below:
// ptr below is a socket ptr identified by PTR_TO_BTF_ID
u64 param[2] = { ptr, val };
bpf_seq_printf(seq, fmt, sizeof(fmt), param, sizeof(param));
In this case, the 16 bytes stack for "param" contains:
8 bytes for ptr with spilled PTR_TO_BTF_ID
8 bytes for val as STACK_MISC
The current verifier will complain the ptr should not be visible
to the helper.
...
16: (7b) *(u64 *)(r10 -64) = r2
18: (7b) *(u64 *)(r10 -56) = r1
19: (bf) r4 = r10
;
20: (07) r4 += -64
; BPF_SEQ_PRINTF(seq, fmt1, (long)s, s->sk_protocol);
21: (bf) r1 = r6
22: (18) r2 = 0xffffa8d00018605a
24: (b4) w3 = 10
25: (b4) w5 = 16
26: (85) call bpf_seq_printf#125
R0=inv(id=0) R1_w=ptr_seq_file(id=0,off=0,imm=0)
R2_w=map_value(id=0,off=90,ks=4,vs=144,imm=0) R3_w=inv10
R4_w=fp-64 R5_w=inv16 R6=ptr_seq_file(id=0,off=0,imm=0)
R7=ptr_netlink_sock(id=0,off=0,imm=0) R10=fp0 fp-56_w=mmmmmmmm
fp-64_w=ptr_
last_idx 26 first_idx 13
regs=8 stack=0 before 25: (b4) w5 = 16
regs=8 stack=0 before 24: (b4) w3 = 10
invalid indirect read from stack off -64+0 size 16
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200509175915.2476783-1-yhs@fb.com
Diffstat (limited to 'tools/lib/bpf')
0 files changed, 0 insertions, 0 deletions