On 7/18/24 6:21 PM, devel-request@xxxxxxxxxxxxxxxxxxxxxxxxxxx wrote:
Date: Thu, 18 Jul 2024 07:26:02 -0000
From:qiwu.chen@xxxxxxxxxxxxx
Subject: Re: [PATCH] arm64: fix a potential segfault
in arm64_unwind_frame
To:devel@xxxxxxxxxxxxxxxxxxxxxxxxxxx
Message-ID:<20240718072602.21739.62283@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
Content-Type: text/plain; charset="utf-8"
Hi Lianbo,
1. The current issue can be reproduced with arm64_unwind_frame_v2():
Thank you for the confirmation, qiwu.
If so, the same changes should be done in the arm64_unwind_frame_v2().
What do you think?
Thanks
Lianbo
crash> bt
[Detaching after fork from child process 4778]
Thread 1 "crash" received signal SIGSEGV, Segmentation fault.
0x0000555555826dae in arm64_unwind_frame_v2 (bt=0x7fffffffd8f0,
frame=0x7fffffffd060, ofp=0x555559909970) at arm64.c:3048
3048 frame->pc = GET_STACK_ULONG(fp + 8);
(gdb) bt
#0 0x0000555555826dae in arm64_unwind_frame_v2 (bt=0x7fffffffd8f0,
frame=0x7fffffffd060, ofp=0x555559909970) at arm64.c:3048
#1 0x0000555555827d99 in arm64_back_trace_cmd_v2 (bt=0x7fffffffd8f0) at
arm64.c:3426
#2 0x00005555557df95e in back_trace (bt=0x7fffffffd8f0) at
kernel.c:3240
#3 0x00005555557dd8b8 in cmd_bt () at kernel.c:2881
#4 0x000055555573696b in exec_command () at main.c:893
#5 0x000055555573673e in main_loop () at main.c:840
#6 0x0000555555aa4a61 in captured_main (data=<optimized out>) at
main.c:1284
#7 gdb_main (args=<optimized out>) at main.c:1313
#8 0x0000555555aa4ae0 in gdb_main_entry (argc=<optimized out>,
argv=<optimized out>) at main.c:1338
#9 0x00005555558021df in gdb_main_loop (argc=2, argv=0x7fffffffe248) at
gdb_interface.c:81
#10 0x0000555555736401 in main (argc=3, argv=0x7fffffffe248) at
main.c:721
(gdb) p/x *(struct arm64_stackframe *)0x7fffffffd060
$1 = {fp = 0xffffffc008003f50, sp = 0xffffffc008003f40, pc =
0xffffffdfd669447c}
(gdb) p/x *(struct bt_info *)0x7fffffffd8f0
$2 = {task = 0xffffff8118012500, flags = 0x0, instptr =
0xffffffdfd669447c, stkptr = 0xffffffc008003f40, bptr = 0x0, stackbase =
0xffffffc01b5b0000, stacktop = 0xffffffc01b5b4000,
stackbuf = 0x555556117a80, tc = 0x55557a3b3480, hp = 0x0, textlist =
0x0, ref = 0x0, frameptr = 0xffffffc008003f50, call_target = 0x0,
machdep = 0x0, debug = 0x0, eframe_ip = 0x0, radix = 0x0,
cpumask = 0x0}
2. The issue can be easily reproduced by "echo c >
/proc/sysrq-trigger" on Andriod GKI-5.10 platform.
>From the reproduced dump we can see, the current fp/sp of crashing
cpu1 is out of range task's stack, but located in the irq stack of cpu0
KERNEL: vmlinux [TAINTED]
DUMPFILE: SYS_COREDUMP
CPUS: 8 [OFFLINE: 7]
MACHINE: aarch64 (unknown Mhz)
MEMORY: 8 GB
PANIC: "Kernel panic - not syncing: sysrq triggered crash"
PID: 9089
COMMAND: "sh"
TASK: ffffff8118012500 [THREAD_INFO: ffffff8118012500]
CPU: 1
STATE: TASK_RUNNING (PANIC)
crash> help -m |grep irq
irq_stack_size: 16384
irq_stacks[0]: ffffffc008000000
irq_stacks[1]: ffffffc008008000
irq_stacks[2]: ffffffc008010000
irq_stacks[3]: ffffffc008018000
irq_stacks[4]: ffffffc008020000
irq_stacks[5]: ffffffc008028000
irq_stacks[6]: ffffffc008030000
irq_stacks[7]: ffffffc008038000
crash> task_struct.thread -x ffffff8118012500
thread = {
cpu_context = {
x19 = 0xffffff80c01ea500,
x20 = 0xffffff8118012500,
x21 = 0xffffff8118012500,
x22 = 0xffffff80c01ea500,
x23 = 0xffffff8118012500,
x24 = 0xffffff81319ac270,
x25 = 0xffffffdfd8f87000,
x26 = 0xffffff8118012500,
x27 = 0xffffffdfd88ea180,
x28 = 0xffffffdfd7e1b4b8,
fp = 0xffffffc01b5b3a10,
sp = 0xffffffc01b5b3a10,
pc = 0xffffffdfd667b89c
},
crash> bt -S 0xffffffc01b5b3a10
PID: 9089 TASK: ffffff8118012500 CPU: 1 COMMAND: "sh"
#0 [ffffffc008003f50] local_cpu_stop at ffffffdfd6694478
crash> bt -S ffffffc008003f50
PID: 9089 TASK: ffffff8118012500 CPU: 1 COMMAND: "sh"
bt: non-process stack address for this task: ffffffc008003f50
(valid range: ffffffc01b5b0000 - ffffffc01b5b4000)
The second frame begins to switch to irq stack of cpu0.
crash> rd ffffffc008003f50 2
ffffffc008003f50: ffffffc008003f70 ffffffdfd68125d0 p?.......%......
crash> dis -x ffffffdfd68125d0
0xffffffdfd68125d0 <handle_percpu_devid_fasteoi_ipi+0xb0>: b
0xffffffdfd6812730 <handle_percpu_devid_fasteoi_ipi+0x210>
crash> rd ffffffc008003f70 2
ffffffc008003f70: ffffffc008003fb0 ffffffdfd680352c .?......,5......
crash> dis ffffffdfd680352c -x
0xffffffdfd680352c <__handle_domain_irq+0x114>: bl
0xffffffdfd673d204 <__irq_exit_rcu>
crash> rd ffffffc008003fb0 2
ffffffc008003fb0: ffffffc008003fe0 ffffffdfd6610380 .?........a.....
crash> dis -x ffffffdfd6610380
0xffffffdfd6610380 <gic_handle_irq.30555+0x6c>: cbz w0,
0xffffffdfd6610348 <gic_handle_irq.30555+0x34>
crash> rd ffffffc008003fe0 2
ffffffc008003fe0: ffffffdfd8d83e20 ffffffdfd6612624
>......$&a.....
crash> dis -x ffffffdfd6612624
0xffffffdfd6612624 <el1_irq+0xe4>: mov sp, x19
crash> rd ffffffdfd8d83e20 2
ffffffdfd8d83e20: ffffffdfd8d83e80 ffffffdfd768c690
.>........h.....
crash> dis -x ffffffdfd768c690
0xffffffdfd768c690 <cpuidle_enter_state+0x3a4>: tbnz w19, #31,
0xffffffdfd768c720 <cpuidle_enter_state+0x434>
crash> rd ffffffdfd8d83e80 2
ffffffdfd8d83e80: ffffffdfd8d83ef0 ffffffdfd67ab4f4
.>........z.....
crash> dis -x ffffffdfd67ab4f4
0xffffffdfd67ab4f4 <do_idle+0x308>: str xzr, [x19, #8]
crash> rd ffffffdfd8d83ef0 2
ffffffdfd8d83ef0: ffffffdfd8d83f50 ffffffdfd67ab7e4 P?........z.....
crash> dis -x ffffffdfd67ab7e4
0xffffffdfd67ab7e4 <cpu_startup_entry+0x84>: b
0xffffffdfd67ab7e0 <cpu_startup_entry+0x80>
It's unreasonable cpu1 is in cpu0's irq context, which is far away from
the backtrace showed by "bt -T", so we must avoid this case.
crash> bt -T
PID: 9089 TASK: ffffff8118012500 CPU: 1 COMMAND: "sh"
[ffffffc01b5b3238] vsnprintf at ffffffdfd7075c10
[ffffffc01b5b32b8] sprintf at ffffffdfd707b9e4
[ffffffc01b5b3398] __sprint_symbol at ffffffdfd68abff4
[ffffffc01b5b33c8] symbol_string at ffffffdfd70774ac
[ffffffc01b5b33d8] symbol_string at ffffffdfd7077510
[ffffffc01b5b34c8] string at ffffffdfd70767a8
[ffffffc01b5b34d8] vsnprintf at ffffffdfd7075c2c
[ffffffc01b5b34e8] vsnprintf at ffffffdfd7075fdc
[ffffffc01b5b3518] vscnprintf at ffffffdfd707b8b4
[ffffffc01b5b3558] ktime_get_ts64 at ffffffdfd686a2f8
[ffffffc01b5b3598] data_alloc at ffffffdfd68009b4
[ffffffc01b5b35d8] prb_reserve at ffffffdfd68011b4
[ffffffc01b5b35e8] prb_reserve at ffffffdfd68010a0
[ffffffc01b5b3648] log_store at ffffffdfd67fb024
[ffffffc01b5b3698] number at ffffffdfd7076ea4
[ffffffc01b5b36d8] number at ffffffdfd7076ea4
[ffffffc01b5b3738] vsnprintf at ffffffdfd7075c10
[ffffffc01b5b3778] number at ffffffdfd7076ea4
[ffffffc01b5b37c8] number at ffffffdfd7076ea4
[ffffffc01b5b3828] vsnprintf at ffffffdfd7075c10
[ffffffc01b5b3868] vsnprintf at ffffffdfd7075c2c
[ffffffc01b5b3888] number at ffffffdfd7076ea4
[ffffffc01b5b38e8] vsnprintf at ffffffdfd7075c10
[ffffffc01b5b3928] vsnprintf at ffffffdfd7075c2c
[ffffffc01b5b3968] aee_nested_printf at ffffffdfd3d05d7c [mrdump]
[ffffffc01b5b3a48] mrdump_common_die at ffffffdfd3d05a98 [mrdump]
[ffffffc01b5b3ac8] ipanic at ffffffdfd3d06078 [mrdump]
[ffffffc01b5b3ae8] __typeid__ZTSFiP14notifier_blockmPvE_global_addr at
ffffffdfd7e3c118
[ffffffc01b5b3af0] ipanic.cfi_jt at ffffffdfd3d0ab40 [mrdump]
[ffffffc01b5b3b18] atomic_notifier_call_chain at ffffffdfd678236c
[ffffffc01b5b3b28] panic at ffffffdfd672aa28
[ffffffc01b5b3bf8] rcu_read_unlock.34874 at ffffffdfd718ddfc
[ffffffc01b5b3c58] __handle_sysrq at ffffffdfd718d3c0
[ffffffc01b5b3c68] write_sysrq_trigger at ffffffdfd718ea20
[ffffffc01b5b3cb0] __typeid__ZTSFlP4filePKcmPxE_global_addr at
ffffffdfd7e2fa88
[ffffffc01b5b3cc8] proc_reg_write at ffffffdfd6c56f44
[ffffffc01b5b3cd8] file_start_write at ffffffdfd6b3f884
[ffffffc01b5b3d08] vfs_write at ffffffdfd6b403b4
[ffffffc01b5b3da8] ksys_write at ffffffdfd6b40240
[ffffffc01b5b3df8] __arm64_sys_write at ffffffdfd6b401b4
[ffffffc01b5b3e20] __typeid__ZTSFlPK7pt_regsE_global_addr at
ffffffdfd7e25240
[ffffffc01b5b3e38] el0_svc_common at ffffffdfd6695980
[ffffffc01b5b3e48] el0_da at ffffffdfd7d43e30
[ffffffc01b5b3e58] el0_svc at ffffffdfd7d43d9c
[ffffffc01b5b3e98] el0_sync_handler at ffffffdfd7d43d10
[ffffffc01b5b3ea8] el0_sync at ffffffdfd66128b8
Thanks
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