This is a note to let you know that I've just added the patch titled
sparc32: fix a braino in fault handling in csum_and_copy_..._user()
to the 5.10-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:
sparc32-fix-a-braino-in-fault-handling-in-csum_and_copy_..._user.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1f36cd05e0081f2c75769a551d584c4ffb2a5660 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Sun, 22 Oct 2023 19:34:28 -0400
Subject: sparc32: fix a braino in fault handling in csum_and_copy_..._user()
From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
commit 1f36cd05e0081f2c75769a551d584c4ffb2a5660 upstream.
Fault handler used to make non-trivial calls, so it needed
to set a stack frame up. Used to be
save ... - grab a stack frame, old %o... become %i...
....
ret - go back to address originally in %o7, currently %i7
restore - switch to previous stack frame, in delay slot
Non-trivial calls had been gone since ab5e8b331244 and that code should
have become
retl - go back to address in %o7
clr %o0 - have return value set to 0
What it had become instead was
ret - go back to address in %i7 - return address of *caller*
clr %o0 - have return value set to 0
which is not good, to put it mildly - we forcibly return 0 from
csum_and_copy_{from,to}_iter() (which is what the call of that
thing had been inlined into) and do that without dropping the
stack frame of said csum_and_copy_..._iter(). Confuses the
hell out of the caller of csum_and_copy_..._iter(), obviously...
Reviewed-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
Fixes: ab5e8b331244 "sparc32: propagate the calling conventions change down to __csum_partial_copy_sparc_generic()"
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/sparc/lib/checksum_32.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/sparc/lib/checksum_32.S
+++ b/arch/sparc/lib/checksum_32.S
@@ -463,5 +463,5 @@ ccslow: cmp %g1, 0
* we only bother with faults on loads... */
cc_fault:
- ret
+ retl
clr %o0
Patches currently in stable-queue which might be from viro@xxxxxxxxxxxxxxxxxx are
queue-5.10/sparc32-fix-a-braino-in-fault-handling-in-csum_and_copy_..._user.patch
