From: Jeffrey Walton <noloader@gmail.com>
To: 47429@debbugs.gnu.org
Subject: bug#47429: Re 47429:allocating JIT code buffer failed: Permission denied
Date: Fri, 26 Mar 2021 19:34:24 -0400 [thread overview]
Message-ID: <CAH8yC8=qTLKQZbOC9CGC7eFTn+xyPQw4tds6+e=xAgS8bmA+rQ@mail.gmail.com> (raw)
In-Reply-To: <CAH8yC8m8d5uVWOAFAPdr_v5KCg_o6xAhiU+T17Way3ZaDuetDw@mail.gmail.com>
Dammit, check for the proper return value...
% cat mmap-test.c
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/mman.h>
int main(int argc, char* argv[])
{
size_t len = 10;
int prot = PROT_EXEC | PROT_READ | PROT_WRITE;
int flags = MAP_PRIVATE | MAP_ANONYMOUS;
void *p = mmap (NULL, len, prot, flags, -1, 0);
int err = errno;
if (p != (void*) -1) {
printf("p is good\n");
munmap(p, len);
}
else {
printf("p is bad (%d)\n", err);
}
return 0;
}
% clang -Wall mmap-test.c -o mmap-test.exe
% ./mmap-test.exe
p is bad (13)
That is the permission denied.
Next, avoid W+X:
% cat mmap-test.c
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/mman.h>
int main(int argc, char* argv[])
{
size_t len = 10;
int prot = /*PROT_EXEC |*/ PROT_READ | PROT_WRITE;
int flags = MAP_PRIVATE | MAP_ANONYMOUS;
void *p = mmap (NULL, len, prot, flags, -1, 0);
int err = errno;
if (p != (void*) -1) {
printf("p is good\n");
munmap(p, len);
}
else {
printf("p is bad (%d)\n", err);
}
return 0;
}
It looks like W^X is the culprit.
Jeff
next prev parent reply other threads:[~2021-03-26 23:34 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-26 22:48 bug#47429: allocating JIT code buffer failed: Permission denied Jeffrey Walton
2021-03-26 23:27 ` bug#47429: Re 47429:allocating " Jeffrey Walton
2021-03-26 23:34 ` Jeffrey Walton [this message]
2021-03-27 1:29 ` Jeffrey Walton
2021-03-27 2:39 ` Jeffrey Walton
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