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Subject[PATCH v2] execve: warn if process starts with executable stack
There were few episodes of silent downgrade to an executable stack over

1) linking innocent looking assembly file will silently add executable
stack if proper linker options is not given as well:

$ cat f.S
.intel_syntax noprefix
.globl f

$ cat main.c
void f(void);
int main(void)
return 0;

$ gcc main.c f.S
$ readelf -l ./a.out
GNU_STACK 0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 RWE 0x10

2) converting C99 nested function into a closure

void intsort2(int *base, size_t nmemb, _Bool invert)
int cmp(const void *a, const void *b)
int r = *(int *)a - *(int *)b;
return invert ? -r : r;
qsort(base, nmemb, sizeof(*base), cmp);

will silently require stack trampolines while non-closure version will not.

Without doubt this behaviour is documented somewhere, add a warning so that
developers and users can at least notice. After so many years of x86_64 having
proper executable stack support it should not cause too many problems.

Signed-off-by: Alexey Dobriyan <>

v2: print pathname instead of comm/pid

fs/exec.c | 5 +++++
1 file changed, 5 insertions(+)

--- a/fs/exec.c
+++ b/fs/exec.c
@@ -761,6 +761,11 @@ int setup_arg_pages(struct linux_binprm *bprm,
goto out_unlock;
BUG_ON(prev != vma);

+ if (unlikely(vm_flags & VM_EXEC)) {
+ pr_warn_once("process '%pD4' started with executable stack\n",
+ bprm->file);
+ }
/* Move stack pages down in memory. */
if (stack_shift) {
ret = shift_arg_pages(vma, stack_shift);
 \ /
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