Messages in this thread | | | Date | Sun, 25 Jul 2021 00:02:58 +0800 | From | Jisheng Zhang <> | Subject | Re: [PATCH RESEND] riscv: stacktrace: Fix NULL pointer dereference |
| |
Hi @Palmer,
On Fri, 16 Jul 2021 07:07:24 -0700 Atish Patra <atishp@atishpatra.org> wrote:
> On Fri, Jul 16, 2021 at 6:47 AM Jisheng Zhang wrote: > > > > From: Jisheng Zhang <jszhang@kernel.org> > > > > 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] [<ffffffff80004922>] walk_stackframe+0xc4/0xdc > > [ 0.407032] [<ffffffff8000496a>] dump_backtrace+0x30/0x38 > > [ 0.407797] [<ffffffff803d7100>] show_stack+0x40/0x4c > > [ 0.408234] [<ffffffff803d9e5c>] dump_stack+0x90/0xb6 > > [ 0.409019] [<ffffffff8040423e>] ptdump_init+0x20/0xc4 > > [ 0.409681] [<ffffffff800015b6>] do_one_initcall+0x4c/0x226 > > [ 0.410110] [<ffffffff80401094>] kernel_init_freeable+0x1f4/0x258 > > [ 0.410562] [<ffffffff803dba88>] kernel_init+0x22/0x148 > > [ 0.410959] [<ffffffff800029e2>] 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 <jszhang@kernel.org> > > --- > > 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 <atish.patra@wdc.com> >
| |