6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mikhail Zaslonko [ Upstream commit 012bfcd5a51082d5a65f096dfb9ca652b5267965 ] When debug_register_static() fails, it clears areas, active_pages and active_entries but leaves the area bounds unchanged. Copying such an area, either by opening its view file or via debug_dump(), makes debug_info_copy() dereference the NULL pointers. Skip the copy loop when the source has no areas. Closes: https://lore.kernel.org/r/20260903132123.12F271F00A3F@smtp.kernel.org Fixes: d72541f94512 ("s390/debug: add early tracing support") Signed-off-by: Mikhail Zaslonko Reviewed-by: Peter Oberparleiter Acked-by: Heiko Carstens Signed-off-by: Heiko Carstens Signed-off-by: Sasha Levin --- arch/s390/kernel/debug.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/s390/kernel/debug.c b/arch/s390/kernel/debug.c index 4cbad08453edc..c4db346688ed8 100644 --- a/arch/s390/kernel/debug.c +++ b/arch/s390/kernel/debug.c @@ -346,7 +346,8 @@ static debug_info_t *debug_info_copy(debug_info_t *in, int mode) debug_info_free(rc); } while (1); - if (mode == NO_AREAS) + /* debug_register_static() failure leaves areas NULL, bounds intact */ + if (mode == NO_AREAS || !in->areas) goto out; for (i = 0; i < in->nr_areas; i++) { -- 2.53.0