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| author | Jose E. Marchesi <jose.marchesi@oracle.com> | 2024-05-08 12:13:13 +0200 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2024-05-09 00:00:55 +0200 |
| commit | 009367099eb61a4fc2af44d4eb06b6b4de7de6db (patch) | |
| tree | fe2af65273e1e7981a195649bf2770c2cac00298 /tools/lib/bpf | |
| parent | bpf: guard BPF_NO_PRESERVE_ACCESS_INDEX in skb_pkt_end.c (diff) | |
| download | linux-009367099eb61a4fc2af44d4eb06b6b4de7de6db.tar.xz linux-009367099eb61a4fc2af44d4eb06b6b4de7de6db.zip | |
bpf: Avoid uninitialized value in BPF_CORE_READ_BITFIELD
[Changes from V1:
- Use a default branch in the switch statement to initialize `val'.]
GCC warns that `val' may be used uninitialized in the
BPF_CRE_READ_BITFIELD macro, defined in bpf_core_read.h as:
[...]
unsigned long long val; \
[...] \
switch (__CORE_RELO(s, field, BYTE_SIZE)) { \
case 1: val = *(const unsigned char *)p; break; \
case 2: val = *(const unsigned short *)p; break; \
case 4: val = *(const unsigned int *)p; break; \
case 8: val = *(const unsigned long long *)p; break; \
} \
[...]
val; \
} \
This patch adds a default entry in the switch statement that sets
`val' to zero in order to avoid the warning, and random values to be
used in case __builtin_preserve_field_info returns unexpected values
for BPF_FIELD_BYTE_SIZE.
Tested in bpf-next master.
No regressions.
Signed-off-by: Jose E. Marchesi <jose.marchesi@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240508101313.16662-1-jose.marchesi@oracle.com
Diffstat (limited to 'tools/lib/bpf')
| -rw-r--r-- | tools/lib/bpf/bpf_core_read.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/tools/lib/bpf/bpf_core_read.h b/tools/lib/bpf/bpf_core_read.h index b5c7ce5c243a..c0e13cdf9660 100644 --- a/tools/lib/bpf/bpf_core_read.h +++ b/tools/lib/bpf/bpf_core_read.h @@ -104,6 +104,7 @@ enum bpf_enum_value_kind { case 2: val = *(const unsigned short *)p; break; \ case 4: val = *(const unsigned int *)p; break; \ case 8: val = *(const unsigned long long *)p; break; \ + default: val = 0; break; \ } \ val <<= __CORE_RELO(s, field, LSHIFT_U64); \ if (__CORE_RELO(s, field, SIGNED)) \ |