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SubjectRe: [PATCH] more sanity checks in Dwarf2 unwinder
Date
On Wednesday 29 November 2006 12:13, Jan Beulich wrote:
> Tighten the requirements on both input to and output from the Dwarf2
> unwinder.

Thanks for doing this.

> while (unwind(info) == 0 && UNW_PC(info)) {
> n++;
> oad->ops->address(oad->data, UNW_PC(info));
> if (arch_unw_user_mode(info))
> break;
> + if ((sp & ~(PAGE_SIZE - 1)) == (UNW_SP(info) & ~(PAGE_SIZE - 1))
> + && sp > UNW_SP(info))
> + break;

Hmm, but that wouldn't catch the case when the SP is completely
corrupted for some reason.
Maybe it would be better to just run a brute force check here like
the old in_exception_stack(). Similar on x86-64.

> + if (UNW_PC(frame) % state.codeAlign
> + || UNW_SP(frame) % sleb128abs(state.dataAlign)
> + || (pc == UNW_PC(frame) && sp == UNW_SP(frame)))
> + return -EIO;

Would it be possible to add printks for the EIOs? We want to know
when dwarf2 is corrupted.

-Andi
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