Messages in this thread | | | Date | Sun, 6 Oct 2013 12:44:32 +0530 | Subject | Re: [Query] Stack Overflow in "arch/arm/kernel/unwind.c" while unwinding frame | From | Anurag Aggarwal <> |
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From what I saw, it happened when the next page is not mapped to physical memory.
I don't think that stack corruption can cause this.
From what I could understand about of the code there is not check if the memory beyond stack is physically mapped or not.
To handle the problem I thought that checks can also be added in unwind_exec_insn() function for stack overflow.
On Wed, Oct 2, 2013 at 11:41 PM, Catalin Marinas <catalin.marinas@arm.com> wrote: > On 24 September 2013 07:23, Anurag Aggarwal <anurag19aggarwal@gmail.com> wrote: >> While executing unwind backtrace instructions in ARM, in the function >> unwind_exec_insn() >> there are chances that SP overflows from stack. >> >> >> For example while executing instruction with opcode 0xAE, vsp can go >> beyond stack to area that has not been allocated till now. >> >> unsigned long *vsp = (unsigned long *)ctrl->vrs[SP]; >> int reg; >> >> /* pop R4-R[4+bbb] */ >> for (reg = 4; reg <= 4 + (insn & 7); reg++) >> ctrl->vrs[reg] = *vsp++; >> >> The above scenario can happen while executing any of the unwind instruction. >> >> One of the ways to fix the problem is to check for vsp with stack >> limits before we increment it, but doing it for all the instructions >> seems a little bad. >> >> I just want to know that if anyone has faced the problem before > > I haven't seen it but I think with some stack (or unwind bytecode) > corruption it could happen. > > I think we could place some checks only when vsp is assigned and return > -URC_FAILURE, together with some warning. > > -- > Catalin
-- Anurag Aggarwal
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