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Fri, 28 Aug 2026 05:38:15 +0000 (GMT) Received: from li-7bb28a4c-2dab-11b2-a85c-887b5c60d769.ibm.com.com (unknown [9.39.23.28]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 28 Aug 2026 05:38:15 +0000 (GMT) From: Shrikanth Hegde To: tglx@kernel.org, maddy@linux.ibm.com, linuxppc-dev@lists.ozlabs.org Cc: sshegde@linux.ibm.com, linux-kernel@vger.kernel.org, chleroy@kernel.org, sbhat@linux.ibm.com, mkchauras@gmail.com Subject: [PATCH] powerpc/entry: Clear TIF_SYSCALL_RET before syscall error return Date: Fri, 28 Aug 2026 11:08:11 +0530 Message-ID: <20260828053811.1042300-1-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.54.0 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-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=TfimcxQh c=1 sm=1 tr=0 ts=6a911ecf cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=9LtnQKmw8N2LNxAaoRgA:9 X-Proofpoint-Spam-Info: AW1haW4tMjYwODI4MDA0NSBTYWx0ZWRfXzvVe72u3ORHh rwxDJQYY+u09XIWFDB4jzM3jt6Q1xwL/8U6Fi3BWlOc9GrRFqvvjcz1WW8r9CO8rSm6V9tmdn6r nrRhRy8v3EdQRkpAGY9vHsrVVqmeKrg= X-Proofpoint-GUID: kAeXcJ71knUp0ddX_mtcGjEC5-YqlAG5 X-Proofpoint-ORIG-GUID: OwMzcmJVHOrxPdN_w33fQJk6HikXmKVu X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODI4MDA0NSBTYWx0ZWRfX+qFbffDRptja 2cVkB+ZzwLO8Ut9ONjVY2tT/F/TG8OSG8oaz9LrXxMBtDrEzqRI3ePIbXIBKBUh5BKchqWWhGOF jxqToeDn/U7lRr7k4v4PVbyTjNkbXOeb43Y0Zx3bHZ4I6H8FMVWCNKJxm0rj+/uuQE49RuEy3G5 HDQit8BAcOVfPIHZxS91db346J+kuireB3YG4aVh1PTaGmFhXf9PQuIu02e4XAo85sSbuy7fx84 e5t7icmXKuOoZep14bjrBNefSTKZFWwN4kNTAGNL518XveHpx8HZsnKvF8pD53h8kA8+vgkC9+G WhIkRg2sDLPeCPVOd8LZybfWtI+GCABQvwwfGeebH4h5O42+YSzo1ZdpWtMsIsV1nu76aDnM+b9 5NdvzqA0A1vqmCvwF3m0mWi9MPel0ZvHWj50LFD1j7d8Kaq12DitAlZEGYaQqclhinMuHCemIU1 Kqy5tFUYN8TPIEEmVMg== 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=2026-08-28_01,2026-08-27_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 spamscore=0 bulkscore=0 malwarescore=0 priorityscore=1501 lowpriorityscore=0 clxscore=1015 phishscore=0 impostorscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608280045 Shivaprasad reported a boot failure due to userspace processes crash on abort() from libc.so.6. It was bisected to merge request commit '3424d8c18a7d ("Merge tag 'core-entry-2026-08-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip")' Upon checking the merge, when syscall_enter_from_user_mode_randomize_stack fails, which could happen when a tracer like seccomp or ptrace intercepts and skips the syscall, the code returns to userspace immediately without clearing the intermediate flag which was set. When the next syscall is made, it immediately aborts the valid syscall since the flag is still set. Hence clear the flag on occurrence of first failure. Reported-by: Shivaprasad G Bhat Closes: https://lore.kernel.org/all/e301014d-568f-4ed5-bc64-b8a85ca0b1e1@linux.ibm.com/ Fixes: 3424d8c18a7d ("Merge tag 'core-entry-2026-08-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip") Signed-off-by: Shrikanth Hegde --- PS: I have kept the block below since earlier code was checking it regardless of result of syscall_enter_from_user_mode. If it turns out to be a redundant, it can be removed later. arch/powerpc/kernel/syscall.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/syscall.c b/arch/powerpc/kernel/syscall.c index 4916c205c4bb..fbefe1927b10 100644 --- a/arch/powerpc/kernel/syscall.c +++ b/arch/powerpc/kernel/syscall.c @@ -18,8 +18,10 @@ notrace long system_call_exception(struct pt_regs *regs, unsigned long r0) long ret; syscall_fn f; - if (unlikely(!syscall_enter_from_user_mode_randomize_stack(regs, &r0))) + if (unlikely(!syscall_enter_from_user_mode_randomize_stack(regs, &r0))) { + clear_thread_flag(TIF_SYSCALL_RET); return syscall_get_error(current, regs); + } if (unlikely(test_and_clear_thread_flag(TIF_SYSCALL_RET))) return syscall_get_error(current, regs); -- 2.47.3