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Sat, 24 Jul 2021 16:09:55 +0000 Received: from email6.ustc.edu.cn ([2001:da8:d800::8] helo=ustc.edu.cn) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m7KDn-007PCy-30 for linux-riscv@lists.infradead.org; Sat, 24 Jul 2021 16:09:53 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mail.ustc.edu.cn; s=dkim; h=Received:Date:From:To:Cc:Subject: Message-ID:In-Reply-To:References:MIME-Version:Content-Type: Content-Transfer-Encoding; bh=GAR4WWqAXHVgE5qg2lxEmsawH6VzLA7G6o qKmn9MhG0=; b=vARQtY1nDQKC1pwGtR68vqFZtjr/vwNUZIl2fqttkiMKIBpv/6 j12/vL8IB7AwXjCBtD+cvfvJuyVh9VofF3OSlygCJv4t7RxoCk29vkZP5ajjd9LF oXtDich8vvxMGI0i2tOr2NyXbxt4Sgz9SpO6lS0nTffYNwgybiW0z2AG8= Received: from xhacker (unknown [101.86.20.15]) by newmailweb.ustc.edu.cn (Coremail) with SMTP id LkAmygAnL3cdO_xgxE0+AA--.8738S2; Sun, 25 Jul 2021 00:09:01 +0800 (CST) Date: Sun, 25 Jul 2021 00:02:58 +0800 From: Jisheng Zhang To: Atish Patra Cc: Paul Walmsley , Palmer Dabbelt , Albert Ou , linux-riscv , "linux-kernel@vger.kernel.org List" Subject: Re: [PATCH RESEND] riscv: stacktrace: Fix NULL pointer dereference Message-ID: <20210725000258.1ca59266@xhacker> In-Reply-To: References: <20210716214051.32eea3a8@xhacker> MIME-Version: 1.0 X-CM-TRANSID: LkAmygAnL3cdO_xgxE0+AA--.8738S2 X-Coremail-Antispam: 1UD129KBjvJXoWxuryftrWUZF1DJw1xKF13twb_yoWrCrWfpF 15JF17CrW8Jr1xtw17tr15ZF15Ar1DAa43Jr9xAr1FyFyUWr1UXw18tFW5WF1qyrn5Ja4x trn0gws2vr4DJ3DanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUy2b7Iv0xC_KF4lb4IE77IF4wAFF20E14v26r1j6r4UM7CY07I2 0VC2zVCF04k26cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rw A2F7IY1VAKz4vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Xr0_Ar1l84ACjcxK6xII jxv20xvEc7CjxVAFwI0_Cr0_Gr1UM28EF7xvwVC2z280aVAFwI0_Gr0_Cr1l84ACjcxK6I 8E87Iv6xkF7I0E14v26r4j6r4UJwAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC 0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr 1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcVAKI48JMxAIw28IcxkI7VAKI48JMxC20s02 6xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_Jr I_JrWlx4CE17CEb7AF67AKxVWUAVWUtwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v2 6r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVWUJVW8JwCI42IY6xAIw20EY4v20xvaj4 0_WFyUJVCq3wCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r1j 6r4UYxBIdaVFxhVjvjDU0xZFpf9x07jOb18UUUUU= X-CM-SenderInfo: xmv2xttqjtqzxdloh3xvwfhvlgxou0/ X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210724_090951_621515_EE6DB109 X-CRM114-Status: GOOD ( 21.36 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org Hi @Palmer, On Fri, 16 Jul 2021 07:07:24 -0700 Atish Patra wrote: > On Fri, Jul 16, 2021 at 6:47 AM Jisheng Zhang wrote: > > > > From: Jisheng Zhang > > > > When CONFIG_FRAME_POINTER=y, calling dump_stack() can always trigger > > NULL pointer dereference panic similar as below: > > > > [ 0.396060] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.13.0-rc5+ #47 > > [ 0.396692] Hardware name: riscv-virtio,qemu (DT) > > [ 0.397176] Call Trace: > > [ 0.398191] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000960 > > [ 0.399487] Oops [#1] > > [ 0.399739] Modules linked in: > > [ 0.400135] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.13.0-rc5+ #47 > > [ 0.400570] Hardware name: riscv-virtio,qemu (DT) > > [ 0.400926] epc : walk_stackframe+0xc4/0xdc > > [ 0.401291] ra : dump_backtrace+0x30/0x38 > > [ 0.401630] epc : ffffffff80004922 ra : ffffffff8000496a sp : ffffffe000f3bd00 > > [ 0.402115] gp : ffffffff80cfdcb8 tp : ffffffe000f30000 t0 : ffffffff80d0b0cf > > [ 0.402602] t1 : ffffffff80d0b0c0 t2 : 0000000000000000 s0 : ffffffe000f3bd60 > > [ 0.403071] s1 : ffffffff808bc2e8 a0 : 0000000000001000 a1 : 0000000000000000 > > [ 0.403448] a2 : ffffffff803d7088 a3 : ffffffff808bc2e8 a4 : 6131725dbc24d400 > > [ 0.403820] a5 : 0000000000001000 a6 : 0000000000000002 a7 : ffffffffffffffff > > [ 0.404226] s2 : 0000000000000000 s3 : 0000000000000000 s4 : 0000000000000000 > > [ 0.404634] s5 : ffffffff803d7088 s6 : ffffffff808bc2e8 s7 : ffffffff80630650 > > [ 0.405085] s8 : ffffffff80912a80 s9 : 0000000000000008 s10: ffffffff804000fc > > [ 0.405388] s11: 0000000000000000 t3 : 0000000000000043 t4 : ffffffffffffffff > > [ 0.405616] t5 : 000000000000003d t6 : ffffffe000f3baa8 > > [ 0.405793] status: 0000000000000100 badaddr: 0000000000000960 cause: 000000000000000d > > [ 0.406135] [] walk_stackframe+0xc4/0xdc > > [ 0.407032] [] dump_backtrace+0x30/0x38 > > [ 0.407797] [] show_stack+0x40/0x4c > > [ 0.408234] [] dump_stack+0x90/0xb6 > > [ 0.409019] [] ptdump_init+0x20/0xc4 > > [ 0.409681] [] do_one_initcall+0x4c/0x226 > > [ 0.410110] [] kernel_init_freeable+0x1f4/0x258 > > [ 0.410562] [] kernel_init+0x22/0x148 > > [ 0.410959] [] ret_from_exception+0x0/0x14 > > [ 0.412241] ---[ end trace b2ab92c901b96251 ]--- > > [ 0.413099] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b > > > > The reason is the task is NULL when we finally call walk_stackframe() > > the NULL is passed from __dump_stack(): > > > > |static void __dump_stack(void) > > |{ > > | dump_stack_print_info(KERN_DEFAULT); > > | show_stack(NULL, NULL, KERN_DEFAULT); > > |} > > > > Fix this issue by checking "task == NULL" case in walk_stackframe(). > > > > Fixes: eac2f3059e02 ("riscv: stacktrace: fix the riscv stacktrace when CONFIG_FRAME_POINTER enabled" Missed a ")" at the end here, do you want a resend? PS: This patch is missed for twice. Thanks > > Signed-off-by: Jisheng Zhang > > --- > > arch/riscv/kernel/stacktrace.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c > > index bde85fc53357..7bc8af75933a 100644 > > --- a/arch/riscv/kernel/stacktrace.c > > +++ b/arch/riscv/kernel/stacktrace.c > > @@ -27,7 +27,7 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs, > > fp = frame_pointer(regs); > > sp = user_stack_pointer(regs); > > pc = instruction_pointer(regs); > > - } else if (task == current) { > > + } else if (task == NULL || task == current) { > > fp = (unsigned long)__builtin_frame_address(1); > > sp = (unsigned long)__builtin_frame_address(0); > > pc = (unsigned long)__builtin_return_address(0); > > -- > > 2.32.0 > > > > > > > > _______________________________________________ > > linux-riscv mailing list > > linux-riscv@lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/linux-riscv > > > Reviewed-by: Atish Patra > _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv