Re: [RFC PATCH v3 2/4] arm64: Check the return PC against unreliable code sections
From: Madhavan T. Venkataraman <hidden>
Date: 2021-05-06 15:21:44
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From: Madhavan T. Venkataraman <hidden>
Date: 2021-05-06 15:21:44
Also in:
live-patching, lkml
On 5/6/21 8:45 AM, Mark Brown wrote:
On Wed, May 05, 2021 at 01:48:21PM -0500, Madhavan T. Venkataraman wrote:quoted
On 5/5/21 11:46 AM, Mark Brown wrote:quoted
quoted
I think that works even if it's hard to love the goto, might want some defensiveness to ensure we can't somehow end up in an infinite loop with a sufficiently badly formed stack.quoted
I could do something like this:quoted
unwind_frame() { int i; ... for (i = 0; i < MAX_CHECKS; i++) { if (!check_frame(tsk, frame)) break; }I think that could work, yes. Have to see the actual code (and other people's opinions!).quoted
If this is acceptable, then the only question is - what should be the value of MAX_CHECKS (I will rename it to something more appropriate)?I'd expect something like 10 to be way more than we'd ever need, or we could define it down to the 2 checks we expect to be possible ATM to be conservative. I'm tempted to be permissive if we have sufficient other checks but I'm not 100% sure on that.
OK. I will implement these changes for version 4 and send it out so this whole thing can be reviewed again with the actual changes in front of us. Madhavan _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel