| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.18 761/879] s390/perf: obtain sie_block from the right address | Date | Tue, 7 Jun 2022 19:04:39 +0200 |
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From: Nico Boehr <nrb@linux.ibm.com>
commit c9bfb460c3e4da2462e16b0f0b200990b36b1dd2 upstream.
Since commit 1179f170b6f0 ("s390: fix fpu restore in entry.S"), the sie_block pointer is located at empty1[1], but in sie_block() it was taken from empty1[0].
This leads to a random pointer being dereferenced, possibly causing system crash.
This problem can be observed when running a simple guest with an endless loop and recording the cpu-clock event:
sudo perf kvm --guestvmlinux=<guestkernel> --guest top -e cpu-clock
With this fix, the correct guest address is shown.
Fixes: 1179f170b6f0 ("s390: fix fpu restore in entry.S") Cc: stable@vger.kernel.org Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Reviewed-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Nico Boehr <nrb@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- arch/s390/kernel/perf_event.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/s390/kernel/perf_event.c +++ b/arch/s390/kernel/perf_event.c @@ -30,7 +30,7 @@ static struct kvm_s390_sie_block *sie_bl if (!stack) return NULL; - return (struct kvm_s390_sie_block *) stack->empty1[0]; + return (struct kvm_s390_sie_block *)stack->empty1[1]; } static bool is_in_guest(struct pt_regs *regs)
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