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Fri, 03 Jul 2026 08:55:48 +0000 (GMT) Received: from smtpav01.fra02v.mail.ibm.com (smtpav01.fra02v.mail.ibm.com [10.20.54.100]) by smtprelay01.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 6638tiD043843996 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 3 Jul 2026 08:55:44 GMT Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 982AB20040; Fri, 3 Jul 2026 08:55:44 +0000 (GMT) Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BE94820043; Fri, 3 Jul 2026 08:55:42 +0000 (GMT) Received: from fedora (unknown [9.5.7.39]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTPS; Fri, 3 Jul 2026 08:55:42 +0000 (GMT) Date: Fri, 3 Jul 2026 14:25:47 +0530 From: Amit Machhiwal To: "Mukesh Kumar Chaurasiya (IBM)" Cc: maddy@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, chleroy@kernel.org, mkchauras@linux.ibm.com, sshegde@linux.ibm.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] powerpc/ptrace: Add offsetof check for exit_flags in pt_regs_check() Message-ID: <20260703134456.2d291388-8b-amachhiw@linux.ibm.com> Mail-Followup-To: "Mukesh Kumar Chaurasiya (IBM)" , maddy@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, chleroy@kernel.org, mkchauras@linux.ibm.com, sshegde@linux.ibm.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org References: <20260703074948.1668744-1-mkchauras@gmail.com> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260703074948.1668744-1-mkchauras@gmail.com> X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzAzMDA4MyBTYWx0ZWRfX2sYSKGQdl6G6 CNMOeltq9RI193rg8sDzYagPdtF5zEHtIP3cEkW1JMXlw/Vl+pyQpbJMOhHUvW6GviM3FWKKeME /gV8OOCPtLWgbXdyR+WFB+b5amoQPaFabSEpplYVMCnh1d/VAr7OLed/EOvr1bAYnXJVE57iKwj A3T1OgsFSXfPb1Jnaf6ZFrbnHFf9e34crgeURd6wEjcJxzIHN5118rixA7LWfqSXjsfl70oY5Us c0l+h0OqnW4hSytLarm0QDfxUm/0gJkvzoNFHGyIiwOgVsKplRu6msBXSMmJ3xVoP9iaVTSNdC9 CT2Aow06y7zssMdt5fK8/wEDGJ4kP0Ll4L98Fsht8fFCEYCRZ1GnQTKwGS8II2Z1n/3fmvjd/oe WRzQS6ePuBgsDsxDDCCzulbFFsqkgVZCLPlIaDPqhlDskVd8pxiKsNV/6hqB7XLSwgkA07NbkEr Adk3h+h8LbtNJUHhtmQ== X-Proofpoint-GUID: jWINDpUbeklN-6HRgeiOFVovJ2MtXf2o X-Authority-Analysis: v=2.4 cv=Z8bc2nRA c=1 sm=1 tr=0 ts=6a477915 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VwQbUJbxAAAA:8 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=gHNQbWQ14yc8XukLhS8A:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzAzMDA4MyBTYWx0ZWRfX5xXFdx2ISZm/ rZRIKw49F5IFUjpkAo3cPD8ya6N1KD+hZZx+QxrM2FCB4XeRV3p5O0B3BVbE63KHDJrR9E7Aaow klj4uUDl/66HRVwwexewL8Csw50pvCA= X-Proofpoint-ORIG-GUID: 5LAoR5CTZsDk5GnTDeBiKh9KrYPMWw30 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-07-03_02,2026-06-26_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 adultscore=0 spamscore=0 priorityscore=1501 impostorscore=0 malwarescore=0 phishscore=0 bulkscore=0 lowpriorityscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607030083 On 2026/07/03 01:19 PM, Mukesh Kumar Chaurasiya (IBM) wrote: > pt_regs_check() verifies that fields shared between struct pt_regs and > struct user_pt_regs sit at the same offset, to catch any accidental > layout divergence between the kernel and uapi structures. > > Add the missing check for exit_flags, following the same pattern as the > existing checks for result, dsisr, dar and the other shared fields. > > Fixes: d7a6797e0bc1 ("powerpc: add exit_flags field in pt_regs") You may want to add below in order to get this patch backported: Cc: stable@vger.kernel.org > Signed-off-by: Mukesh Kumar Chaurasiya (IBM) > --- > arch/powerpc/kernel/ptrace/ptrace.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/powerpc/kernel/ptrace/ptrace.c b/arch/powerpc/kernel/ptrace/ptrace.c > index 316d4f5ead8e..fb3fec73f66a 100644 > --- a/arch/powerpc/kernel/ptrace/ptrace.c > +++ b/arch/powerpc/kernel/ptrace/ptrace.c > @@ -235,6 +235,8 @@ void __init pt_regs_check(void) > offsetof(struct user_pt_regs, dsisr)); > BUILD_BUG_ON(offsetof(struct pt_regs, result) != > offsetof(struct user_pt_regs, result)); > + BUILD_BUG_ON(offsetof(struct pt_regs, exit_flags) != > + offsetof(struct user_pt_regs, exit_flags)); At first, it appeared to be redundant as we already check CHECK_REG(PT_EXIT_FLAGS, exit_flags); which expands to: #define CHECK_REG(_pt, _reg) \ BUILD_BUG_ON(_pt != (offsetof(struct user_pt_regs, _reg) / \ sizeof(unsigned long))); But looking closely, it turns out to be non-redundant. CHECK_REG only touches struct user_pt_regs — it validates the PT_EXIT_FLAGS constant against the uapi layout. It says nothing about struct pt_regs. struct pt_regs (asm/ptrace.h) embeds struct user_pt_regs in a union alongside an anonymous struct that re-declares all the same fields with kernel-internal aliases (dear/dar, esr/dsisr). exit_flags lives in that anonymous struct. A field accidentally inserted there between result and exit_flags would silently break the union aliasing without CHECK_REG catching it. The new BUILD_BUG_ON closes that gap, consistent with how result, dar and dsisr are already protected in the same block. Looks good to me. Reviewed-by: Amit Machhiwal Thanks, Amit > > BUILD_BUG_ON(sizeof(struct user_pt_regs) > sizeof(struct pt_regs)); > > -- > 2.55.0 > >