Fix compat_sys_sigpending breakage

fbb77611 · Dmitry V. Levin <[email protected]> · 2017-08-05 23:00:50 +03:00

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]>

Commit: fbb77611e95d3d5b2af86a59754a3130877cb667
Parents: 0fdd951c

Changes

1 files changed · +7 −4

File	Status	Add	Del	Content
kernel/signal.c	modified	+7	−4	View file

kernel/signal.c

View file

diff --git a/kernel/signal.c b/kernel/signal.c
index caed913..7e33f8c 100644
--- 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
 