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Thu, 26 Feb 2026 05:18:32 +0000 (GMT) Date: Thu, 26 Feb 2026 10:48:28 +0530 From: Vishal Chourasia To: Ethan Tidmore Cc: tglx@kernel.org, peterz@infradead.org, mpe@ellerman.id.au, cai@lca.pw, linux-kernel@vger.kernel.org Subject: Re: [PATCH] sched/core: Fix error pointer dereference Message-ID: References: <20260217180633.524129-1-ethantidmore06@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260217180633.524129-1-ethantidmore06@gmail.com> X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-ORIG-GUID: dsYNcHXLJkRW-xzJAA41DD6EpUTRafMS X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMjI2MDA0MyBTYWx0ZWRfX3bjPwGcd9BxH ri5krt4N4xBFflgVnLncc2tZZoT7EFOnVzLWgwPysegkxhLItfHBZoj6VuB9uKV26u7CiMamQ2B A3MdS6FDVkhtkgwLfGqqvDfk2c+La3U8fWDYYQIe49DbdrjrDHd4jtMs1pU1CD08m6cGeZTObT/ Q/Xp9AWU7XtdZlOcT9A8z1wtQuGzSAEiHdTVkJdLcZ3FYa/92APohHvF7b68O/TO+r7CwaQWsEJ CsTI2vmswqAZsqsJy0OZ4OmABVHMX6UC9eyyUjd70Ark0XGT5/3Hgo4kucygTI1/8QlLbUxopwx 8VYwDNTNQ4Y3O6TR6eqmpHlzaOD8la1a8VntglRs6RnKX15TmRvYUYLGQ5wM9ydLo2sOs8qKSK0 Rq2PmXqe2i63ADo1ELdflsNGxfns4XAb3rDHcrKM1XAFdPawmIt/aSGnbhuT2IE3/NihH5THOuW CyBmcGgUzy1hkHqjf7Q== X-Proofpoint-GUID: rD4Li8HqdO3zrdFoKyHnIBOX5sigAdUp X-Authority-Analysis: v=2.4 cv=bbBmkePB c=1 sm=1 tr=0 ts=699fd7ae cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=kj9zAlcOel0A:10 a=HzLeVaNsDn8A:10 a=VkNPw1HP01LnGYTKEx00:22 a=Mpw57Om8IfrbqaoTuvik:22 a=GgsMoib0sEa3-_RKJdDe:22 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=kB6ZBcHm7mOKkhUwCNgA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-02-25_04,2026-02-25_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 bulkscore=0 adultscore=0 impostorscore=0 lowpriorityscore=0 priorityscore=1501 suspectscore=0 clxscore=1011 phishscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2601150000 definitions=main-2602260043 On Tue, Feb 17, 2026 at 12:06:33PM -0600, Ethan Tidmore wrote: > The function idle_thread_get() can return an error pointer and is not > checked for one. Add check for error pointer. > > Detected by Smatch: > kernel/cpu.c:911 finish_cpu() error: > 'idle' dereferencing possible ERR_PTR() > > Fixes: bf2c59fce4074 ("sched/core: Fix illegal RCU from offline CPUs") > Signed-off-by: Ethan Tidmore > --- > kernel/cpu.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/kernel/cpu.c b/kernel/cpu.c > index bc4f7a9ba64e..30af888d1bc1 100644 > --- a/kernel/cpu.c > +++ b/kernel/cpu.c > @@ -908,7 +908,12 @@ static int bringup_cpu(unsigned int cpu) > static int finish_cpu(unsigned int cpu) > { > struct task_struct *idle = idle_thread_get(cpu); > - struct mm_struct *mm = idle->active_mm; > + struct mm_struct *mm; > + > + if (IS_ERR(idle)) > + return PTR_ERR(idle); > + > + mm = idle->active_mm; > > /* > * sched_force_init_mm() ensured the use of &init_mm, > -- > 2.53.0 > Reviewed-by: Vishal Chourasia