From: Willy Tarreau w@1wt.eu
stable inclusion from stable-v5.10.94 commit 5e258640ba549a3a2d053a917b353889beab09f4 bugzilla: https://gitee.com/openeuler/kernel/issues/I531X9
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit ebbe0d8a449d183fa43b42d84fcb248e25303985 upstream.
After re-checking in the spec and comparing stack offsets with glibc, The last pushed argument must be 16-byte aligned (i.e. aligned before the call) so that in the callee esp+4 is multiple of 16, so the principle is the 32-bit equivalent to what Ammar fixed for x86_64. It's possible that 32-bit code using SSE2 or MMX could have been affected. In addition the frame pointer ought to be zero at the deepest level.
Link: https://gitlab.com/x86-psABIs/i386-ABI/-/wikis/Intel386-psABI Cc: Ammar Faizi ammar.faizi@students.amikom.ac.id Cc: stable@vger.kernel.org Signed-off-by: Willy Tarreau w@1wt.eu Signed-off-by: Paul E. McKenney paulmck@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Acked-by: Xie XiuQi xiexiuqi@huawei.com --- tools/include/nolibc/nolibc.h | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/tools/include/nolibc/nolibc.h b/tools/include/nolibc/nolibc.h index bab456bb970a..ff8695c0f899 100644 --- a/tools/include/nolibc/nolibc.h +++ b/tools/include/nolibc/nolibc.h @@ -606,13 +606,21 @@ struct sys_stat_struct { })
/* startup code */ +/* + * i386 System V ABI mandates: + * 1) last pushed argument must be 16-byte aligned. + * 2) The deepest stack frame should be set to zero + * + */ asm(".section .text\n" ".global _start\n" "_start:\n" "pop %eax\n" // argc (first arg, %eax) "mov %esp, %ebx\n" // argv[] (second arg, %ebx) "lea 4(%ebx,%eax,4),%ecx\n" // then a NULL then envp (third arg, %ecx) - "and $-16, %esp\n" // x86 ABI : esp must be 16-byte aligned when + "xor %ebp, %ebp\n" // zero the stack frame + "and $-16, %esp\n" // x86 ABI : esp must be 16-byte aligned before + "sub $4, %esp\n" // the call instruction (args are aligned) "push %ecx\n" // push all registers on the stack so that we "push %ebx\n" // support both regparm and plain stack modes "push %eax\n"