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Thu, 3 Sep 2026 13:07:34 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 3 Sep 2026 13:07:34 +0000 (GMT) From: Mikhail Zaslonko To: linux-s390@vger.kernel.org Cc: Heiko Carstens , Alexander Gordeev , Vasily Gorbik , Ilya Leoshkevich , Peter Oberparleiter Subject: [PATCH v3 1/3] s390/debug: Fix NULL pointer dereference in debug_set_level() Date: Thu, 3 Sep 2026 15:07:31 +0200 Message-ID: <20260903130733.709001-2-zaslonko@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260903130733.709001-1-zaslonko@linux.ibm.com> References: <20260903130733.709001-1-zaslonko@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=EIc2FVZC c=1 sm=1 tr=0 ts=6a99711b cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VnNF1IyMAAAA:8 a=rWNA1FonZI2w8RDMTWgA:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTAzMDExMyBTYWx0ZWRfX2PZJKVgOI6v3 hWYS9CC6TjcUrag8+AAHEAOX1cgYZli/YHuRoE320dnPTpkS8m3EZFK8DBl6w+Cj5h/Ykrl/wqx XetFziwStjgqUzYw3ggr4X2isUsDAi1cg/Dyx/A9wj8yWepcR5RAbet0E3iGhrA8NFcQrV2hKos lhjhc2qSgpSsomwENlfI30mIE3KpQZESteT/kUgno4TASo8qXkcvQttRLzvMQHo9/UzTnObNynX vCSYXP9k6JzRpy4iwIC2WWZZMycLFTrd6XGZwrOOOOtXqOGA0gf9LCVEdjVIGxGxDArULKbbztP RulvzO8WJONPs315uuRZUbvqmpVdq31RNecmJYmkWGczYCozqAJtyF9r0chFD2LMhPr3zzMy4ZL AXDWZhZ0RJqEG6QpO5T1iKVdDFQjMlqZ39GprTTu01TslauVllGLu8c8Kc9JnymYfJW82jXk6nL zsfvqSHgkPM+kCVWEMg== X-Proofpoint-GUID: nNKNexFCcQdndz-qDW7ZubZJZaqzzu8k X-Proofpoint-ORIG-GUID: nNKNexFCcQdndz-qDW7ZubZJZaqzzu8k X-Proofpoint-Spam-Info: AW1haW4tMjYwOTAzMDExMyBTYWx0ZWRfX5QGOrE8l5p41 s+taPIY1oWh0jWM2YGIQo1z753RUpbh3HTa7+5cyJdU+pFE1Y8QOHFe5hCtIPXJBxwii8p7ZUvk N39JVl4dp0lm+SuCXR0sSRG1EaChOUM= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-03_03,2026-09-03_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 impostorscore=0 suspectscore=0 priorityscore=1501 clxscore=1015 phishscore=0 spamscore=0 adultscore=0 lowpriorityscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2609030113 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 --- 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); -- 2.55.0