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bpf: Account for insn->off when doing bpf_probe_read_kernel

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In the bpf interpreter mode, bpf_probe_read_kernel is used to read
from PTR_TO_BTF_ID's kernel object.  It currently missed considering
the insn->off.  This patch fixes it.

Fixes: 2a02759ef5 ("bpf: Add support for BTF pointers to interpreter")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20191107014640.384083-1-kafai@fb.com
This commit is contained in:
Martin KaFai Lau 2019-11-06 17:46:40 -08:00 committed by Alexei Starovoitov
parent ed57802121
commit 85d31dd070
1 changed files with 1 additions and 1 deletions
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2
kernel/bpf/core.c
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@ -1569,7 +1569,7 @@ out:
#undef LDST
#define LDX_PROBE(SIZEOP, SIZE) \
LDX_PROBE_MEM_##SIZEOP: \
bpf_probe_read_kernel(&DST, SIZE, (const void *)(long) SRC); \
bpf_probe_read_kernel(&DST, SIZE, (const void *)(long) (SRC + insn->off)); \
CONT;
LDX_PROBE(B, 1)
LDX_PROBE(H, 2)