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Mon, 12 Oct 2026 07:05:08 +0000 (GMT) Received: from tuxmaker.linux.ibm.com (unknown [9.87.85.9]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTPS; Mon, 12 Oct 2026 07:05:07 +0000 (GMT) From: Sven Schnelle To: Heiko Carstens Cc: Alexander Gordeev , Vasily Gorbik , Christian Borntraeger , linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: Re: [PATCH] s390/uprobes: Fix off-by-one bug in emulated PER handling In-Reply-To: <20261009132604.2434271-1-hca@linux.ibm.com> (Heiko Carstens's message of "Fri, 9 Oct 2026 15:26:04 +0200") References: <20261009132604.2434271-1-hca@linux.ibm.com> Date: Mon, 12 Oct 2026 09:05:07 +0200 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDEyMDAyNiBTYWx0ZWRfX8rUyY5Igegig E7qjupxD7tXx23SSkG4wyAWNo3l4DTVc+4stLyQRrEQkhMQmJXduNYlDNi6JDutCiUZZz1jFLga i2O6efuPHA4jitYCnQefqbJY5WVC/Bd6iHBvIATralAU0tY6e0MehU/yTFsESCd4rnLrTguz+xd w88xwU85IUpIQCdUvMy5zH3sawZZlYuSycDVPHEdbj+0HwLzdGFjB4c78vwEkwfj2pu5jM6Mgt2 mJSOgQPvscUN1cHbvLx0YdnyW8tRJXdwmrUmMNLr1n3ovq+c2ljnvUCwR61GZ0my5WNa8a2eblO ZYk/L6LEh6riJuNFfYl4sJmKOaB4Z0YbPAjxQWUqrA/xswlRVK3qCDu6C1fDV6Wwhe9doBoQQI0 k8YE82jg8czXt8DoH88nOH1MxeCKpvYfoaLghAKykUIr4Kg0Yqc31S69jFyDv3Nn/Y0z2Yk5JkD VDtAQ3Jgk6uUrJb9eVQ== X-Proofpoint-GUID: e3o8cxNSJ2zkq2KBARHHJQ8XJV6JsKdm X-Proofpoint-ORIG-GUID: e3o8cxNSJ2zkq2KBARHHJQ8XJV6JsKdm X-Proofpoint-Spam-Info: AW1haW4tMjYxMDEyMDAyNiBTYWx0ZWRfX5MLwCN3NbyOw hWxQdicPYuIDM3dmpFb2sh7yhbfDnfxsdigwx3puBQLUOKGogsC10FgolPcfU/mBsgcThW7wEJu 52Dggx3DZQpYdDty/oxihhb52866rec= X-Authority-Analysis: v=2.4 cv=btHZl0ai c=1 sm=1 tr=0 ts=6acc86a8 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VnNF1IyMAAAA:8 a=KGQMB7Ug8lH89wmqnMIA:9 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=2026-10-12_02,2026-10-09_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 malwarescore=0 phishscore=0 impostorscore=0 adultscore=0 lowpriorityscore=0 priorityscore=1501 clxscore=1015 spamscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610080000 definitions=main-2610120026 Heiko Carstens writes: > The uprobes code emulates some instructions, and with that also > PER storage-alteration handling, in case a debugger is attached. > > The PER storage-alteration handling contains an off-by-one bug, which > may lead to PER traps which should not happen. Adjust the comparison > in sim_stor_event() to fix that. > > Fixes: 8d1a2427d8fc ("s390/uprobes: fix user space PER events") > Signed-off-by: Heiko Carstens > --- > arch/s390/kernel/uprobes.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/s390/kernel/uprobes.c b/arch/s390/kernel/uprobes.c > index c624f3361e43..b2b8a377ced6 100644 > --- a/arch/s390/kernel/uprobes.c > +++ b/arch/s390/kernel/uprobes.c > @@ -241,7 +241,7 @@ static void sim_stor_event(struct pt_regs *regs, void *addr, int len) > return; > if (!(current->thread.per_user.control & PER_EVENT_STORE)) > return; > - if ((void *)current->thread.per_user.start > (addr + len)) > + if ((void *)current->thread.per_user.start > (addr + len - 1)) > return; > if ((void *)current->thread.per_user.end < addr) > return; Reviewed-by: Sven Schnelle