This is a note to let you know that I've just added the patch titled
ARM: ptrace: Restore syscall restart tracing
to the 5.15-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:
arm-ptrace-restore-syscall-restart-tracing.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 35a98f2a07c6e3f7606f44aa3236aa513b500918
Author: Kees Cook <keescook@xxxxxxxxxxxx>
Date: Thu Aug 10 12:54:18 2023 -0700
ARM: ptrace: Restore syscall restart tracing
[ Upstream commit cf007647475b5090819c5fe8da771073145c7334 ]
Since commit 4e57a4ddf6b0 ("ARM: 9107/1: syscall: always store
thread_info->abi_syscall"), the seccomp selftests "syscall_restart" has
been broken. This was caused by the restart syscall not being stored to
"abi_syscall" during restart setup before branching to the "local_restart"
label. Tracers would see the wrong syscall, and scno would get overwritten
while returning from the TIF_WORK path. Add the missing store.
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxxxx>
Cc: Lecopzer Chen <lecopzer.chen@xxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Fixes: 4e57a4ddf6b0 ("ARM: 9107/1: syscall: always store thread_info->abi_syscall")
Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx>
Link: https://lore.kernel.org/r/20230810195422.2304827-1-keescook@xxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index fde7ac271b147..e7bfdd10bbcd3 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -101,6 +101,7 @@ slow_work_pending:
cmp r0, #0
beq no_work_pending
movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
+ str scno, [tsk, #TI_ABI_SYSCALL] @ make sure tracers see update
ldmia sp, {r0 - r6} @ have to reload r0 - r6
b local_restart @ ... and off we go
ENDPROC(ret_fast_syscall)
