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s390/signal: fix endless loop in do_signal

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No upstream commit exists: the problem addressed here is that 'commit
75309018a2 ("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 56e62a7370
("s390: convert to generic entry")', 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 788d082426 ("io_uring: import 5.15-stable io_uring")'
Fixes: 75309018a2 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sumanth Korikkar 2023-02-15 15:13:24 +01:00 committed by Greg Kroah-Hartman
parent c261f798f7
commit 645df4047b
1 changed files with 1 additions and 1 deletions
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2
arch/s390/kernel/signal.c
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@ -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;