On Tue, Jan 18, 2022 at 7:37 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote: > When building with -Warray-bounds, this warning was emitted: > > In function 'memset', > inlined from 'vtpm_proxy_fops_read' at drivers/char/tpm/tpm_vtpm_proxy.c:102:2: > ./include/linux/fortify-string.h:43:33: warning: '__builtin_memset' pointer overflow between offset 164 and size [2147483648, 4294967295] > [-Warray-bounds] > 43 | #define __underlying_memset __builtin_memset > | ^ Can you explain what that compiler warning actually means, and which compiler it is from? Is this from a 32-bit or a 64-bit architecture? It sounds like the compiler (GCC?) is hallucinating a codepath on which "len" is guaranteed to be >=2147483648, right? Why is it doing that? Is this some kinda side effect from the fortify code?
