Fix compat_sys_sigpending breakage

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.

Reported-by: Anatoly Pugachev <[email protected]>
Inspired-by: Eugene Syromyatnikov <[email protected]>
Fixes: 8f13621abced ("sigpending(): move compat to native")
Signed-off-by: Dmitry V. Levin <[email protected]>
Acked-by: Al Viro <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/kernel/signal.c b/kernel/signal.c
index caed9133ae52733aa96baf74cb4ef3c344832125..7e33f8c583e64c91d7cb6ac1fb330b01299b7be2 100644 (file)
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -3303,12 +3303,15 @@ SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
 #ifdef CONFIG_COMPAT
 COMPAT_SYSCALL_DEFINE1(sigpending, compat_old_sigset_t __user *, set32)
 {
+#ifdef __BIG_ENDIAN
        sigset_t set;
-       int err = do_sigpending(&set, sizeof(old_sigset_t)); 
-       if (err == 0)
-               if (copy_to_user(set32, &set, sizeof(old_sigset_t)))
-                       err = -EFAULT;
+       int err = do_sigpending(&set, sizeof(set.sig[0]));
+       if (!err)
+               err = put_user(set.sig[0], set32);
        return err;
+#else
+       return sys_rt_sigpending((sigset_t __user *)set32, sizeof(*set32));
+#endif
 }
 #endif