The latest change of compat_sys_sigpending in commit 8f13621abced ("sigpending(): move compat to native") has broken it in two ways. First, it tries to write 4 bytes more than userspace expects: sizeof(old_sigset_t) == sizeof(long) == 8 instead of sizeof(compat_old_sigset_t) == sizeof(u32) == 4. Second, on big endian architectures these bytes are being written in the wrong order. This bug was found by strace test suite.
Unified · Split
| @@ -3303,12 +3303,15 @@ SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set) · 3302 unmodified lines | ||
| 3303 | 3303 | #ifdef CONFIG_COMPAT |
| 3304 | 3304 | COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32) |
| 3305 | 3305 | { |
| 3306 | +#ifdef __BIG_ENDIAN | |
| 3306 | 3307 | sigset_t set; |
| 3307 | − int err = do_sigpending(&set, sizeof(old_sigset_t)); | |
| 3308 | − if (err == 0) | |
| 3309 | − if (copy_to_user(set32, &set, sizeof(old_sigset_t))) | |
| 3310 | − err = -EFAULT; | |
| 3308 | + int err = do_sigpending(&set, sizeof(set.sig[0])); | |
| 3309 | + if (!err) | |
| 3310 | + err = put_user(set.sig[0], set32); | |
| 3311 | 3311 | return err; |
| 3312 | +#else | |
| 3313 | + return sys_rt_sigpending((sigset_t __user *)set32, sizeof(*set32)); | |
| 3314 | +#endif | |
| 3312 | 3315 | } |
| 3313 | 3316 | #endif |
| 3314 | 3317 | |