linux-kernel - Re: [PATCH] objtool: Fix stack overflow in validate

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Message-ID: <aS8Rxqvdg28C7wNS@gmail.com>
Date: Tue, 2 Dec 2025 17:20:22 +0100
From: Ingo Molnar <mingo@...nel.org>
To: Josh Poimboeuf <jpoimboe@...nel.org>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org,
	Nathan Chancellor <nathan@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Alexandre Chartre <alexandre.chartre@...cle.com>,
	David Laight <david.laight.linux@...il.com>
Subject: Re: [PATCH] objtool: Fix stack overflow in validate_branch()


* Josh Poimboeuf <jpoimboe@...nel.org> wrote:

> On an allmodconfig kernel compiled with Clang, objtool is segfaulting in
> drivers/scsi/qla2xxx/qla2xxx.o due to a stack overflow in
> validate_branch().
> 
> Due in part to KASAN being enabled, the qla2xxx code has a large number
> of conditional jumps, causing objtool to go quite deep in its recursion.
> 
> By far the biggest offender of stack usage is the recently added
> 'prev_state' stack variable in validate_insn(), coming in at 328 bytes.

That's weird - how can a user-space tool run into stack 
limits, are they set particularly conservatively?

In any case, applied to tip:objtool/urgent, thanks!

	Ingo