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Thu, 24 Sep 2026 11:57:25 +0000 (GMT) Received: from tuxmaker.lnxne.boe (unknown [9.87.85.9]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 24 Sep 2026 11:57:25 +0000 (GMT) From: Heiko Carstens To: Alexander Gordeev , Sven Schnelle , Vasily Gorbik , Christian Borntraeger Cc: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: [PATCH] s390/kprobes: Prevent kprobes on instructions with exception table entry Date: Thu, 24 Sep 2026 13:57:24 +0200 Message-ID: <20260924115725.1108581-1-hca@linux.ibm.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: mhwT4rIvLa3p8yTzCbZSzTBodmqLzv4u X-Authority-Analysis: v=2.4 cv=EOCTQFZC c=1 sm=1 tr=0 ts=6ab5102a cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=3K4JMSNACPa9h271a24A:9 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTI0MDA0OCBTYWx0ZWRfX24cmoQ3Xos/i XoMFM3zWtyxSFlztTNWDX2JyIszBwrWhrkKz5UqVFtPLrf+RwncMjpkcs/D7Mp0qOU55sjWMcJa q/HmV/8Jz/b9eyYJPnlmELRvXOS+Ax0= X-Proofpoint-GUID: mhwT4rIvLa3p8yTzCbZSzTBodmqLzv4u X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTI0MDA0OCBTYWx0ZWRfX97l3lTA1DvXx OSj1PDAmUl7g/ZcPWIZMtL9nX1JpEW/u8UJNWQkxHYaYmKGeAl++shq9s8Gnzae9y3NtM6Wa4md 5pkAiPv/TrhD5XpWXde0ueXGVk06uQNjLgsPhiYnFaQZs5xbmdJRk6KxFt8x4ZC5+PVbOHJNapU P09Mk+pq/UWHCYVnh5wF6Of3RFgtIKll930YNP+MnZVveeWbpOWXmAV/D28c4cajW7NnpW4UED+ 9iec7QAZLc385TMZHfHfxwyMn7VXopMnQXjK/RwcBM1BN/kkhzU16TwctGZFEd68bEy5GsLzc/D Nxdd9TJ9AEh9AlCzdYo+RodmDvhEzbUyPwJ8Nwz4w2f3afs3AGyzy9LU3FvrQCdHhfykbl3j7ac QzgRTUAIKXjjru8JH6FYNewj2Uw4PaJo3QxEkdfNzzxbp8Q73C3kP6XIEq+cZ3PQT8k3zf5OQUq WRarfG22fbYyYWDS4ng== 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=2026-09-24_02,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 phishscore=0 priorityscore=1501 clxscore=1015 spamscore=0 adultscore=0 impostorscore=0 lowpriorityscore=0 suspectscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609240048 The mvcos exception handler ex_handler_ua_mvcos() decodes the faulting instruction, assuming it is an mvcos instruction. In case the instruction is kprobed the decoded instruction is a breakpoint instruction instead, which leads to incorrect instruction decoding and potential register corruption. Fix this by simply preventing to set a kprobe on such instructions, similar like arm64 is doing it. Fixes: c488f5187a24 ("s390/uaccess: Shorten raw_copy_from_user() / raw_copy_to_user() inline assemblies") Cc: stable@vger.kernel.org Signed-off-by: Heiko Carstens --- arch/s390/kernel/kprobes.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c index c450120b4474..e806b124e4ba 100644 --- a/arch/s390/kernel/kprobes.c +++ b/arch/s390/kernel/kprobes.c @@ -85,6 +85,9 @@ static bool can_probe(unsigned long paddr) if (!kallsyms_lookup_size_offset(paddr, NULL, &offset)) return false; + if (s390_search_extables(paddr)) + return false; + /* Decode instructions */ addr = paddr - offset; while (addr < paddr) { -- 2.53.0