On 7/24/24 9:36 AM, devel-request@xxxxxxxxxxxxxxxxxxxxxxxxxxx wrote:
Date: Wed, 24 Jul 2024 01:36:09 -0000
From:qiwu.chen@xxxxxxxxxxxxx
Subject: [PATCH v2] arm64: fix a potential segfault
when unwind frame
To:devel@xxxxxxxxxxxxxxxxxxxxxxxxxxx
Message-ID:<20240724013609.28594.37360@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
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<qiwu.chen@xxxxxxxxxxxxx>
---
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;
Thank you for the update. This looks good, so: Ack.
Lianbo
if (CRASHDEBUG(1))
-- 2.25.1
--
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