Messages in this thread Patch in this message | | | From | Mark-PK Tsai <> | Subject | [PATCH] ARM: fix race in for_each_frame | Date | Tue, 12 Nov 2019 21:29:38 +0800 |
| |
The sv_pc, which is saved in the stack, may be an invalid address if the target thread is running on another processor in the meantime. It will cause kernel crash at `ldr r2, [sv_pc, #-4]`.
Check if sv_pc is valid before use it like unwind_frame in arch/arm/kernel/unwind.c.
Signed-off-by: Mike-SL Lin <mike-sl.lin@mediatek.com> Signed-off-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com> --- arch/arm/lib/backtrace.S | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/arch/arm/lib/backtrace.S b/arch/arm/lib/backtrace.S index 582925238d65..84f06381bbfb 100644 --- a/arch/arm/lib/backtrace.S +++ b/arch/arm/lib/backtrace.S @@ -64,6 +64,11 @@ for_each_frame: tst frame, mask @ Check for address exceptions sub sv_pc, sv_pc, offset @ Correct PC for prefetching bic sv_pc, sv_pc, mask @ mask PC/LR for the mode + mov r0, sv_pc + bl kernel_text_address @ check if sv_pc is valid + cmp r0, #0 @ if sv_pc is not kernel text + beq 1006f @ address, abort backtrace + 1003: ldr r2, [sv_pc, #-4] @ if stmfd sp!, {args} exists, ldr r3, .Ldsi+4 @ adjust saved 'pc' back one teq r3, r2, lsr #11 @ instruction -- 2.18.0 | |