[Crash-utility] Re: [PATCH] X86 64: fix a regression issue about kernel stack padding

Hi Lijiang & Kazu, On Wed, Jun 12, 2024 at 1:03 PM lijiang <lijiang(a)redhat.com&gt; wrote: > > On Wed, Jun 12, 2024 at 12:29 PM HAGIO KAZUHITO(萩尾 一仁) < k-hagio-ab(a)nec.com&gt; wrote: >> >> >> On 2024/06/12 12:42, Lianbo Jiang wrote: >> > The commit 48764a14bc58 may cause a regression issue when the CONFIG_X86_FRED >> > is not enabled, this is because the SIZE(fred_frame) will call the >> > SIZE_verify() to determine if the fred_frame is valid, otherwise it will >> > emit an error: >> > >> > crash> bt 1 >> > >> > bt: invalid structure size: fred_frame >> > FILE: x86_64.c LINE: 4089 FUNCTION: x86_64_low_budget_back_trace_cmd() >> > >> > [/home/k-hagio/bin/crash] error trace: 588df3 => 5cbc72 => 5eb3e1 => 5eb366 >> > PID: 1 TASK: ffff9f94c024b980 CPU: 2 COMMAND: "systemd" >> > #0 [ffffade44001bca8] __schedule at ffffffffb948ebbb >> > #1 [ffffade44001bd10] schedule at ffffffffb948f04d >> > #2 [ffffade44001bd20] schedule_hrtimeout_range_clock at ffffffffb9494fef >> > #3 [ffffade44001bda8] ep_poll at ffffffffb8c91be8 >> > #4 [ffffade44001be48] do_epoll_wait at ffffffffb8c91d11 >> > #5 [ffffade44001be80] __x64_sys_epoll_wait at ffffffffb8c92590 >> > #6 [ffffade44001bed0] do_syscall_64 at ffffffffb947f459 >> > #7 [ffffade44001bf50] entry_SYSCALL_64_after_hwframe at ffffffffb96000ea >> > >> > 5eb366: SIZE_verify.part.42+70 >> > 5eb3e1: SIZE_verify+49 >> > 5cbc72: x86_64_low_budget_back_trace_cmd+3010 >> > 588df3: back_trace+1523 >> > >> > bt: invalid structure size: fred_frame >> > FILE: x86_64.c LINE: 4089 FUNCTION: x86_64_low_budget_back_trace_cmd() >> > >> > Let's replace the SIZE(fred_frame) with the VALID_SIZE(fred_frame) to >> > fix it. >> > >> > Fixes: 48764a14bc58 ("x86_64: fix for adding top_of_kernel_stack_padding for kernel stack") >> > Reported-by: Kazuhito Hagio <k-hagio-ab(a)nec.com&gt; >> > Signed-off-by: Lianbo Jiang <lijiang(a)redhat.com&gt; >> > --- >> > x86_64.c | 4 ++-- >> > 1 file changed, 2 insertions(+), 2 deletions(-) >> > >> > diff --git a/x86_64.c b/x86_64.c >> > index 6777c93e6b47..469d26b05e24 100644 >> > --- a/x86_64.c >> > +++ b/x86_64.c >> > @@ -4086,7 +4086,7 @@ in_exception_stack: >> > >> > if (!irq_eframe && !is_kernel_thread(bt->tc->task) && >> > (GET_STACKBASE(bt->tc->task) == bt->stackbase)) { >> > - long stack_padding_size = SIZE(fred_frame) > 0 ? (2*8) : 0; >> > + long stack_padding_size = VALID_SIZE(fred_frame) ? (2*8) : 0; >> > user_mode_eframe = bt->stacktop - SIZE(pt_regs); >> > if (last_process_stack_eframe < user_mode_eframe) >> > x86_64_exception_frame(EFRAME_PRINT, 0, bt->stackbuf + >> > @@ -4408,7 +4408,7 @@ in_exception_stack: >> > >> > if (!irq_eframe && !is_kernel_thread(bt->tc->task) && >> > (GET_STACKBASE(bt->tc->task) == bt->stackbase)) { >> > - long stack_padding_size = SIZE(fred_frame) > 0 ? (2*8) : 0; >> > + long stack_padding_size = VALID_SIZE(fred_frame) ? (2*8) : 0; >> > user_mode_eframe = bt->stacktop - SIZE(pt_regs); >> > if (last_process_stack_eframe < user_mode_eframe) >> > x86_64_exception_frame(EFRAME_PRINT, 0, bt->stackbuf + >> >> Thanks, tested ok with kernels configured without CONFIG_X86_FRED=y. >> > > Thank you for helping with the test, Kazu. > Thanks for reporting and fixing the code. LGTM, so ack.

Thanks, Tao Liu > Lianbo > >> >> Thanks, >> Kazu