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This causes the interpreter to compute wrong results, creating a mismatch with the verifier's range tracking. For example, INT_MIN / 2 returns 0x40000000 instead of the correct 0xC0000000. The verifier tracks the correct range, so a crafted BPF program can exploit the mismatch for out-of-bounds map value access (confirmed by KASAN). Patch 1 introduces abs_s32() which handles S32_MIN correctly and replaces all 8 abs((s32)...) call sites. s32 is the only affected case -- the s64 handlers do not use abs(). Patch 2 adds selftests covering sdiv32 and smod32 with INT_MIN dividend to prevent regression. Changes since v4: - Renamed __safe_abs32() to abs_s32() and dropped inline keyword per Alexei Starovoitov's feedback Changes since v3: - Fixed stray blank line deletion in the file header - Improved comment per Yonghong Song's suggestion - Added JIT vs interpreter context to selftest commit message Changes since v2: - Simplified to use -(u32)x per Mykyta Yatsenko's suggestion Changes since v1: - Moved helper above kerneldoc comment block to fix build warnings Jenny Guanni Qu (2): bpf: Fix undefined behavior in interpreter sdiv/smod for INT_MIN selftests/bpf: Add tests for sdiv32/smod32 with INT_MIN dividend kernel/bpf/core.c | 22 ++++--- .../selftests/bpf/progs/verifier_sdiv.c | 58 +++++++++++++++++++ 2 files changed, 72 insertions(+), 8 deletions(-) -- 2.34.1