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| author | Stanislav Fomichev <sdf@google.com> | 2019-01-16 14:03:15 -0800 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2019-01-17 16:42:35 +0100 |
| commit | 0b698005a9d11c0e91141ec11a2c4918a129f703 (patch) | |
| tree | 8ba4e8f27f0b2b052d3fdf5f64389b9abb1ca44e /kernel | |
| parent | 6e8ccb4f624a73c56fc6ef0c45bcf91ca80703c3 (diff) | |
| download | lwn-0b698005a9d11c0e91141ec11a2c4918a129f703.tar.gz lwn-0b698005a9d11c0e91141ec11a2c4918a129f703.zip | |
bpf: don't assume build-id length is always 20 bytes
Build-id length is not fixed to 20, it can be (`man ld` /--build-id):
* 128-bit (uuid)
* 160-bit (sha1)
* any length specified in ld --build-id=0xhexstring
To fix the issue of missing BPF_STACK_BUILD_ID_VALID for shorter build-ids,
assume that build-id is somewhere in the range of 1 .. 20.
Set the remaining bytes to zero.
v2:
* don't introduce new "len = min(BPF_BUILD_ID_SIZE, nhdr->n_descsz)",
we already know that nhdr->n_descsz <= BPF_BUILD_ID_SIZE if we enter
this 'if' condition
Fixes: 615755a77b24 ("bpf: extend stackmap to save binary_build_id+offset instead of address")
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/stackmap.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index d9e2483669d0..f9df545e92f6 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -180,11 +180,14 @@ static inline int stack_map_parse_build_id(void *page_addr, if (nhdr->n_type == BPF_BUILD_ID && nhdr->n_namesz == sizeof("GNU") && - nhdr->n_descsz == BPF_BUILD_ID_SIZE) { + nhdr->n_descsz > 0 && + nhdr->n_descsz <= BPF_BUILD_ID_SIZE) { memcpy(build_id, note_start + note_offs + ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr), - BPF_BUILD_ID_SIZE); + nhdr->n_descsz); + memset(build_id + nhdr->n_descsz, 0, + BPF_BUILD_ID_SIZE - nhdr->n_descsz); return 0; } new_offs = note_offs + sizeof(Elf32_Nhdr) + |