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From: Jeff Law <>
Subject: Re: [PATCH] x86: Check corrupted return address when unwinding stack
Date: Fri, 30 Sep 2022 13:33:58 -0600	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On 9/21/22 14:42, H.J. Lu via Gcc-patches wrote:
> If shadow stack is enabled, when unwinding stack, we count how many stack
> frames we pop to reach the landing pad and adjust shadow stack by the same
> amount.  When counting the stack frame, we compare the return address on
> normal stack against the return address on shadow stack.  If they don't
> match, return _URC_FATAL_PHASE2_ERROR for the corrupted return address on
> normal stack.  Don't check the return address for
> 1. Non-catchable exception where exception_class == 0.  Process will be
> terminated.
> 2. Zero return address which marks the outermost stack frame.
> 3. Signal stack frame since kernel puts a restore token on shadow stack.
> 	* unwind-generic.h (_Unwind_Frames_Increment): Add the EXC
> 	argument.
> 	* (_Unwind_RaiseException_Phase2): Pass EXC to
> 	_Unwind_Frames_Increment.
> 	(_Unwind_ForcedUnwind_Phase2): Likewise.
> 	* config/i386/shadow-stack-unwind.h (_Unwind_Frames_Increment):
> 	Take the EXC argument.  Return _URC_FATAL_PHASE2_ERROR if the
> 	return address on normal stack doesn't match the return address
> 	on shadow stack.

The generic bits are fine.  While I'm aware of one other target that 
_might_ need adjustment, it's an out-of-tree target and thus clearly not 
your responsibility.


  reply	other threads:[~2022-09-30 19:34 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-21 20:42 H.J. Lu
2022-09-30 19:33 ` Jeff Law [this message]
2022-10-04 21:32 ` PING^1: " H.J. Lu
2022-10-17  7:24   ` Hongtao Liu

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