[PATCH v2 1/1] s390/signal: fix endless loop in do_signal
No upstream commit exists: the problem addressed here is that
'commit 75309018a24d ("s390: add support for TIF_NOTIFY_SIGNAL")'
was backported to 5.10. This commit is broken, but nobody noticed
upstream, since shortly after s390 converted to generic entry with
'commit 75309018a24d ("s390: add support for TIF_NOTIFY_SIGNAL")', which
implicitly fixed the problem outlined below.
Thread flag is set to TIF_NOTIFY_SIGNAL for io_uring work. The io work
user or syscall calls do_signal when either one of the TIF_SIGPENDING or
TIF_NOTIFY_SIGNAL flag is set. However, do_signal does consider only
TIF_SIGPENDING signal and ignores TIF_NOTIFY_SIGNAL condition. This
means get_signal is never invoked for TIF_NOTIFY_SIGNAL and hence the
flag is not cleared, which results in an endless do_signal loop.
Reference: 'commit 788d0824269b ("io_uring: import 5.15-stable io_uring")'
Fixes: 75309018a24d ("s390: add support for TIF_NOTIFY_SIGNAL")
Cc: stable@vger.kernel.org # 5.10.162
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
---
arch/s390/kernel/signal.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c
index b27b6c1f058d..9e900a8977bd 100644
--- a/arch/s390/kernel/signal.c
+++ b/arch/s390/kernel/signal.c
@@ -472,7 +472,7 @@ void do_signal(struct pt_regs *regs)
current->thread.system_call =
test_pt_regs_flag(regs, PIF_SYSCALL) ? regs->int_code : 0;
- if (test_thread_flag(TIF_SIGPENDING) && get_signal(&ksig)) {
+ if (get_signal(&ksig)) {
/* Whee! Actually deliver the signal. */
if (current->thread.system_call) {
regs->int_code = current->thread.system_call;
--
2.37.2
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