From: "Jose E. Marchesi" jose.marchesi@oracle.com

stable inclusion from stable-v5.10.222 commit b694989bb13ed5f166e633faa1eb0f21c6d261a6 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAHF4L

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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[ Upstream commit 009367099eb61a4fc2af44d4eb06b6b4de7de6db ]

[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 Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Pu Lehui pulehui@huawei.com --- tools/lib/bpf/bpf_core_read.h | 1 + 1 file changed, 1 insertion(+)

diff --git a/tools/lib/bpf/bpf_core_read.h b/tools/lib/bpf/bpf_core_read.h index f05cfc082915..4303b31498d8 100644 --- a/tools/lib/bpf/bpf_core_read.h +++ b/tools/lib/bpf/bpf_core_read.h @@ -101,6 +101,7 @@ 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)) \