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authorStanislav Fomichev <sdf@google.com>2019-01-16 14:03:15 -0800
committerDaniel Borkmann <daniel@iogearbox.net>2019-01-17 16:42:35 +0100
commit0b698005a9d11c0e91141ec11a2c4918a129f703 (patch)
tree8ba4e8f27f0b2b052d3fdf5f64389b9abb1ca44e
parent6e8ccb4f624a73c56fc6ef0c45bcf91ca80703c3 (diff)
download96b-common-0b698005a9d11c0e91141ec11a2c4918a129f703.tar.gz
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>
-rw-r--r--kernel/bpf/stackmap.c7
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) +