fs/signalfd.c: fix inconsistent return codes for signalfd4

The kernel signalfd4() syscall returns different error codes when called
either in compat or native mode.  This behaviour makes correct emulation
in qemu and testing programs like LTP more complicated.

Fix the code to always return -in both modes- EFAULT for unaccessible user
memory, and EINVAL when called with an invalid signal mask.

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Laurent Vivier <laurent@vivier.eu>
Link: http://lkml.kernel.org/r/20200530100707.GA10159@ls3530.fritz.box
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/signalfd.c b/fs/signalfd.c
index 44b6845b071c3321872cfce6d1cf3c672077480f..5b78719be445591b555fd5e57bb6f9df892e1706 100644 (file)
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -314,9 +314,10 @@ SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
 {
        sigset_t mask;
 
-       if (sizemask != sizeof(sigset_t) ||
-           copy_from_user(&mask, user_mask, sizeof(mask)))
+       if (sizemask != sizeof(sigset_t))
                return -EINVAL;
+       if (copy_from_user(&mask, user_mask, sizeof(mask)))
+               return -EFAULT;
        return do_signalfd4(ufd, &mask, flags);
 }
 
@@ -325,9 +326,10 @@ SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask,
 {
        sigset_t mask;
 
-       if (sizemask != sizeof(sigset_t) ||
-           copy_from_user(&mask, user_mask, sizeof(mask)))
+       if (sizemask != sizeof(sigset_t))
                return -EINVAL;
+       if (copy_from_user(&mask, user_mask, sizeof(mask)))
+               return -EFAULT;
        return do_signalfd4(ufd, &mask, 0);
 }