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[44.230.211.174]) by smtp.gmail.com with ESMTPSA id 184sm394733pfc.28.2020.11.30.18.48.13 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Mon, 30 Nov 2020 18:48:13 -0800 (PST) Date: Mon, 30 Nov 2020 18:48:11 -0800 From: Alakesh Haloi To: linux-kernel@vger.kernel.org Cc: Christian Brauner , "Eric W. Biederman" , Oleg Nesterov , Kees Cook , Sargun Dhillon , Minchan Kim , Bernd Edlinger Subject: [PATCH] pid: add null pointer check in pid_nr_ns() Message-ID: <20201201024811.GA72235@ip-172-31-62-0.us-west-2.compute.internal> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There has been at least one occurrence where a null pointer derefernce panic was seen with following stack trace. #0 [ffffff800bcd3800] machine_kexec at ffffff8008095fb4 #1 [ffffff800bcd3860] __crash_kexec at ffffff8008122a30 #2 [ffffff800bcd39f0] panic at ffffff80080aa054 #3 [ffffff800bcd3ae0] die at ffffff800808aee8 #4 [ffffff800bcd3b20] die_kernel_fault at ffffff8008099520 #5 [ffffff800bcd3b50] __do_kernel_fault at ffffff8008098e50 #6 [ffffff800bcd3b80] do_translation_fault at ffffff800809929c #7 [ffffff800bcd3b90] do_mem_abort at ffffff8008081204 #8 [ffffff800bcd3d90] el1_ia at ffffff800808304c PC: ffffff80080c20ec [pid_nr_ns+4] LR: ffffff80080c231c [__task_pid_nr_ns+72] SP: ffffff800bcd3da0 PSTATE: 60000005 X29: ffffff800bcd3da0 X28: ffffffc00691c380 X27: 0000000000000001 X26: 00000000004ce8e8 X25: 00000000004ce8d0 X24: ffffffc00691c3e0 X23: ffffffc004e8c000 X22: 0000000000000000 X21: ffffffc00b042ed2 X20: ffffff800876a4f0 X19: 0000000000000000 X18: 0000000000000000 X17: 0000000000000001 X16: 0000000000000000 X15: 0000000000000000 X14: 0000000400000003 X13: 0000000000000008 X12: fefefefefefefeff X11: 0000000000000000 X10: 0000007fffffffff X9: 00000000004ce8b0 X8: 00000000004ce8b0 X7: 0000000000000000 X6: ffffffc00b042ed2 X5: ffffffc00b042ed2 X4: 0000000000020008 X3: 53206e69616c702f X2: ffffff800876a4f0 X1: ffffff800876a4f0 X0: 53206e69616c702f #9 [ffffff800bcd3da0] pid_nr_ns at ffffff80080c20e8 Signed-off-by: Alakesh Haloi Cc: stable@vger.kernel.org --- kernel/pid.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/pid.c b/kernel/pid.c index a96bc4bf4f86..3767b9e1431d 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -474,7 +474,7 @@ pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns) struct upid *upid; pid_t nr = 0; - if (pid && ns->level <= pid->level) { + if (pid && ns && ns->level <= pid->level) { upid = &pid->numbers[ns->level]; if (upid->ns == ns) nr = upid->nr; -- 2.17.1