netdev - Re: [PATCH] mm: Decline to manipulate the refcount on a slab page

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Message-ID: <Z878K7JQ93LqBdCB@casper.infradead.org>
Date: Mon, 10 Mar 2025 14:50:19 +0000
From: Matthew Wilcox <willy@...radead.org>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: Andrew Morton <akpm@...ux-foundation.org>, netdev@...r.kernel.org,
	linux-mm@...ck.org, Hannes Reinecke <hare@...e.de>
Subject: Re: [PATCH] mm: Decline to manipulate the refcount on a slab page

On Mon, Mar 10, 2025 at 03:37:51PM +0100, Vlastimil Babka wrote:
> Note it's a 6.14 hotfix for kernel oopses due to page refcount overflow.

Not actually overflow ... without VM_DEBUG enabled, networking increases
the refcount from 0 to 1, then decrements it from 1 to 0, causing the
slab to be freed.  So it's a UAF bug induced by a messed-up refcount.