[Crash-utility] Re: [PATCH v2] arm64: fix a potential segfault when unwind frame

Date: Wed, 24 Jul 2024 01:36:09 -0000 From:qiwu.chen@transsion.com Subject: [Crash-utility] [PATCH v2] arm64: fix a potential segfault when unwind frame To:devel@lists.crash-utility.osci.io Message-ID:<20240724013609.28594.37360@lists.crash-utility.osci.io> Content-Type: text/plain; charset="utf-8" The range of frame->fp is checked insufficiently, which may lead to a wrong next fp. As a result, bt->stackbuf will be accessed out of range, and segfault. crash> bt [Detaching after fork from child process 11409] PID: 7661 TASK: ffffff81858aa500 CPU: 4 COMMAND: "sh" #0 [ffffffc008003f50] local_cpu_stop at ffffffdd7669444c Thread 1 "crash" received signal SIGSEGV, Segmentation fault. 0x00005555558266cc in arm64_unwind_frame (bt=0x7fffffffd8f0, frame=0x7fffffffd080) at arm64.c:2821 2821 frame->fp = GET_STACK_ULONG(fp); (gdb) bt arm64.c:2821 out>) at main.c:1338 gdb_interface.c:81 (gdb) p /x *(struct bt_info*) 0x7fffffffd8f0 $3 = {task = 0xffffff81858aa500, flags = 0x0, instptr = 0xffffffdd76694450, stkptr = 0xffffffc008003f40, bptr = 0x0, stackbase = 0xffffffc027288000, stacktop = 0xffffffc02728c000, stackbuf = 0x555556115a40, tc = 0x55559d16fdc0, hp = 0x0, textlist = 0x0, ref = 0x0, frameptr = 0xffffffc008003f50, call_target = 0x0, machdep = 0x0, debug = 0x0, eframe_ip = 0x0, radix = 0x0, cpumask = 0x0} (gdb) p /x *(struct arm64_stackframe*) 0x7fffffffd080 $4 = {fp = 0xffffffc008003f50, sp = 0xffffffc008003f60, pc = 0xffffffdd76694450} crash> bt -S 0xffffffc008003f50 PID: 7661 TASK: ffffff81858aa500 CPU: 4 COMMAND: "sh" bt: non-process stack address for this task: ffffffc008003f50 (valid range: ffffffc027288000 - ffffffc02728c000) Check frame->fp value sufficiently before access it. Only frame->fp within the range of bt->stackbase and bt->stacktop will be regarded as valid. Signed-off-by: qiwu.chen&lt;qiwu.chen(a)transsion.com&gt; --- arm64.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arm64.c b/arm64.c index b3040d7..624dba2 100644 --- a/arm64.c +++ b/arm64.c @@ -2814,7 +2814,7 @@ arm64_unwind_frame(struct bt_info *bt, struct arm64_stackframe *frame) low = frame->sp; high = (low + stack_mask) & ~(stack_mask); - if (fp < low || fp > high || fp & 0xf) + if (fp < low || fp > high || fp & 0xf || !INSTACK(fp, bt)) return FALSE; frame->sp = fp + 0x10; @@ -3024,7 +3024,7 @@ arm64_unwind_frame_v2(struct bt_info *bt, struct arm64_stackframe *frame, low = frame->sp; high = (low + stack_mask) & ~(stack_mask); - if (fp < low || fp > high || fp & 0xf) + if (fp < low || fp > high || fp & 0xf || !INSTACK(fp, bt)) return FALSE;

if (CRASHDEBUG(1)) -- 2.25.1