Kees Cook 23a2b0d100 x86/syscall: Avoid memcpy() for ia32 syscall_get_arguments() ... [ Upstream commit d19d638b1e6cf746263ef60b7d0dee0204d8216a ] Modern (fortified) memcpy() prefers to avoid writing (or reading) beyond the end of the addressed destination (or source) struct member: In function ‘fortify_memcpy_chk’, inlined from ‘syscall_get_arguments’ at ./arch/x86/include/asm/syscall.h:85:2, inlined from ‘populate_seccomp_data’ at kernel/seccomp.c:258:2, inlined from ‘__seccomp_filter’ at kernel/seccomp.c:1231:3: ./include/linux/fortify-string.h:580:25: error: call to ‘__read_overflow2_field’ declared with attribute warning: detected read beyond size of field (2nd parameter); maybe use struct_group()? [-Werror=attribute-warning] 580 | __read_overflow2_field(q_size_field, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ As already done for x86_64 and compat mode, do not use memcpy() to extract syscall arguments from struct pt_regs but rather just perform direct assignments. Binary output differences are negligible, and actually ends up using less stack space: - sub $0x84,%esp + sub $0x6c,%esp and less text size: text data bss dec hex filename 10794 252 0 11046 2b26 gcc-32b/kernel/seccomp.o.stock 10714 252 0 10966 2ad6 gcc-32b/kernel/seccomp.o.after Closes: https://lore.kernel.org/lkml/9b69fb14-df89-4677-9c82-056ea9e706f5@gmail.com/ Reported-by: Mirsad Todorovac <mtodorovac69@gmail.com> Signed-off-by: Kees Cook <kees@kernel.org> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> Acked-by: Dave Hansen <dave.hansen@linux.intel.com> Tested-by: Mirsad Todorovac <mtodorovac69@gmail.com> Link: https://lore.kernel.org/all/20240708202202.work.477-kees%40kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org>		2024-11-23 23:21:39 +01:00
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asm	x86/syscall: Avoid memcpy() for ia32 syscall_get_arguments()	2024-11-23 23:21:39 +01:00
uapi/asm	Import A536BXXU9EXDC	2024-06-15 16:02:09 -03:00