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Tue, 13 Oct 2026 13:34:53 +0000 (GMT) Received: from tuxmaker.lnxne.boe (unknown [9.87.85.9]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 13 Oct 2026 13:34:53 +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 v2 1/2] s390/signal: Fix incorrect return address in signal frame Date: Tue, 13 Oct 2026 15:34:52 +0200 Message-ID: <20261013133453.2288894-2-hca@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261013133453.2288894-1-hca@linux.ibm.com> References: <20261013133453.2288894-1-hca@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-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDEzMDA1MiBTYWx0ZWRfX0GINlBIzNlxx b2H34cW5PcLKd9VgMheBDEz6TEGEUKRQKt0QwSoiVO6Df8QesKtYe5AVyivbF1OEUrlixl7Ho7b NyGdZt8gsV05A9+C/uCjf/gg7G4a7a7MlEfBdiVisgXEB75Qi3nJQU8NxFaKTCYA0Wy7Ffv1lfn t/zKlVbnpHgzzs0YFBCJIprQA3CvIyL7rczJjneLFbTBgDjiDHfCj8NefV4Pgj9DC/G7ydARew2 V6TKcbiHYYD0IgX/jmXCPVSqd4FwmMP3Mr4MaeUnA/91ftyMvK0ietjwJbaXVovGS9lkAmNHu8c AQ4QJ/9Ah1qywcz1PPoFeMGn38WrulRJUW7Qsd8qKa6qa5g862ppyfwDrkl4MaEiC4stPUSRo3K tauJOMWvfsZj6AiD6DZB+MaCwkU/8XGBs/ZB6Z1B8kxi3kP5I6QCYuMLhoky1VDorQWfblVIbTs IZTRefXzZcdqt9Gy6eg== X-Proofpoint-GUID: P4lG1N4nUgF-aHXrvbM0yQNIJ_GvsczX X-Proofpoint-ORIG-GUID: P4lG1N4nUgF-aHXrvbM0yQNIJ_GvsczX X-Proofpoint-Spam-Info: AW1haW4tMjYxMDEzMDA1MiBTYWx0ZWRfX/gAwYBU413tq ibUMflsjtG6Ihu26bELULnuW8TXjPEguiIlx/tud0qYRaVEshyvsdgXmTk2vVc0p229DlQkYhLY 3pmPdVjMdPTH/jFtVyMp8TTWpYipPZQ= X-Authority-Analysis: v=2.4 cv=btHZl0ai c=1 sm=1 tr=0 ts=6ace3383 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=WT4i2XjXIP67Cb3RjXIA: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=2026-10-13_01,2026-10-09_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-2610130052 exit_to_user_mode_loop() can call arch_do_signal_or_restart() multiple times when signals are pending. If the first call set up a vDSO system call restart by saving the real user return address and adjusting psw.addr so it points to the vDSO stub, a second call builds the signal frame with the wrong return address. Restore psw.addr from arch_data, and set the return code to -EINTR before building the signal frame. This requires restart_block.arch_data to be properly initialized for all tasks. Move the initialization in copy_thread() in front of the kernel thread check, so that it also covers kernel threads and their children (PID 1, usermode helpers). Only PID 0 is left uninitialized, since it never returns to user space. Fixes: df29a7440c4b ("s390/signal: switch to using vdso for sigreturn and syscall restart") Cc: stable@vger.kernel.org Signed-off-by: Heiko Carstens --- arch/s390/kernel/process.c | 12 ++++++------ arch/s390/kernel/signal.c | 6 +++++- 2 files changed, 11 insertions(+), 7 deletions(-) diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c index 416650ae4871..4676a6a8257e 100644 --- a/arch/s390/kernel/process.c +++ b/arch/s390/kernel/process.c @@ -131,6 +131,12 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) p->thread.hardirq_timer = 0; p->thread.softirq_timer = 0; p->thread.last_break = 1; + /* + * s390 stores the svc return address in arch_data when calling + * sigreturn()/restart_syscall() via vdso. 1 means no valid address + * stored. + */ + p->restart_block.arch_data = 1; frame->sf.back_chain = 0; frame->sf.gprs[11 - 6] = (unsigned long)&frame->childregs; @@ -168,12 +174,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) p->thread.acrs[0] = (unsigned int)(tls >> 32); p->thread.acrs[1] = (unsigned int)tls; } - /* - * s390 stores the svc return address in arch_data when calling - * sigreturn()/restart_syscall() via vdso. 1 means no valid address - * stored. - */ - p->restart_block.arch_data = 1; return 0; } diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c index 4874de5edea0..b59b0c49a1aa 100644 --- a/arch/s390/kernel/signal.c +++ b/arch/s390/kernel/signal.c @@ -475,7 +475,11 @@ void arch_do_signal_or_restart(struct pt_regs *regs) } /* No longer in a system call */ clear_pt_regs_flag(regs, PIF_SYSCALL); - + if (!(current->restart_block.arch_data & 1)) { + regs->psw.addr = current->restart_block.arch_data; + current->restart_block.arch_data = 1; + regs->gprs[2] = -EINTR; + } rseq_signal_deliver(&ksig, regs); handle_signal(&ksig, oldset, regs); return; -- 2.53.0