This is a note to let you know that I've just added the patch titled
um: properly align signal stack on x86_64
to the 6.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
um-properly-align-signal-stack-on-x86_64.patch
and it can be found in the queue-6.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 9e1057929ba7b48666582ed8e1b9babf0e3edc2a
Author: Benjamin Berg <benjamin.berg@xxxxxxxxx>
Date: Tue Jan 7 14:35:09 2025 +0100
um: properly align signal stack on x86_64
[ Upstream commit 3c2fc7434d90338cf4c1b37bc95994208d23bfc6 ]
The stack needs to be properly aligned so 16 byte memory accesses on the
stack are correct. This was broken when introducing the dynamic math
register sizing as the rounding was not moved appropriately.
Fixes: 3f17fed21491 ("um: switch to regset API and depend on XSTATE")
Signed-off-by: Benjamin Berg <benjamin.berg@xxxxxxxxx>
Link: https://patch.msgid.link/20250107133509.265576-1-benjamin@xxxxxxxxxxxxxxxx
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: Richard Weinberger <richard@xxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/um/signal.c b/arch/x86/um/signal.c
index ea5b3bcc42456..2934e170b0fe0 100644
--- a/arch/x86/um/signal.c
+++ b/arch/x86/um/signal.c
@@ -372,11 +372,13 @@ int setup_signal_stack_si(unsigned long stack_top, struct ksignal *ksig,
int err = 0, sig = ksig->sig;
unsigned long fp_to;
- frame = (struct rt_sigframe __user *)
- round_down(stack_top - sizeof(struct rt_sigframe), 16);
+ frame = (void __user *)stack_top - sizeof(struct rt_sigframe);
/* Add required space for math frame */
- frame = (struct rt_sigframe __user *)((unsigned long)frame - math_size);
+ frame = (void __user *)((unsigned long)frame - math_size);
+
+ /* ABI requires 16 byte boundary alignment */
+ frame = (void __user *)round_down((unsigned long)frame, 16);
/* Subtract 128 for a red zone and 8 for proper alignment */
frame = (struct rt_sigframe __user *) ((unsigned long) frame - 128 - 8);
