From b1eb31d533cdfcae1011ed53850d52f36afe5774 Mon Sep 17 00:00:00 2001 From: Mikhail Zaslonko Date: Thu, 3 Sep 2026 15:07:31 +0200 Subject: [PATCH] s390/debug: Fix NULL pointer dereference in debug_set_level() Commit a2cec6863709 ("s390/debug: Add s390dbf kernel parameter") incorrectly removed a null-id check from debug_set_level(), introducing a possible NULL pointer dereference for debug-API users that put debug_register() results unchecked into debug_set_level(). Fix this by moving the check from the internal _debug_set_level() variant back to the external debug_set_level() wrapper. Fixes: a2cec6863709 ("s390/debug: Add s390dbf kernel parameter") Signed-off-by: Mikhail Zaslonko Reviewed-by: Peter Oberparleiter Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik --- arch/s390/kernel/debug.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/s390/kernel/debug.c b/arch/s390/kernel/debug.c index 14d2b58ad093..e06abf1dbc21 100644 --- a/arch/s390/kernel/debug.c +++ b/arch/s390/kernel/debug.c @@ -1074,9 +1074,6 @@ static void _debug_set_level(debug_info_t *id, int new_level) { unsigned long flags; - if (!id) - return; - if (new_level == DEBUG_OFF_LEVEL) { pr_info("%s: switched off\n", id->name); } else if ((new_level > DEBUG_MAX_LEVEL) || (new_level < 0)) { @@ -1101,6 +1098,9 @@ static void _debug_set_level(debug_info_t *id, int new_level) */ void debug_set_level(debug_info_t *id, int new_level) { + if (!id) + return; + /* Level specified via kernel parameter takes precedence */ debug_get_param(id->name, &new_level, NULL);