From: Deepakkumar Karn <dkarn@redhat.com>
To: djwong@kernel.org
Cc: brauner@kernel.org, dkarn@redhat.com, jack@suse.cz,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
syzbot+e07658f51ca22ab65b4e@syzkaller.appspotmail.com,
syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk
Subject: Re: [PATCH v2] fs: add NULL check in drop_buffers() to prevent null-ptr-deref
Date: Tue, 9 Dec 2025 01:43:33 +0530 [thread overview]
Message-ID: <20251208201333.528909-1-dkarn@redhat.com> (raw)
In-Reply-To: <20251208193024.GA89444@frogsfrogsfrogs>
On Mon, 8 Dec 2025 11:30:24 -0800, Darrick J. Wong wrote:
> > drop_buffers() dereferences the buffer_head pointer returned by
> > folio_buffers() without checking for NULL. This leads to a null pointer
> > dereference when called from try_to_free_buffers() on a folio with no
> > buffers attached. This happens when filemap_release_folio() is called on
> > a folio belonging to a mapping with AS_RELEASE_ALWAYS set but without
> > release_folio address_space operation defined. In such case,
> What user is that? All the users of AS_RELEASE_ALWAYS in 6.18 appear to
> supply a ->release_folio. Is this some new thing in 6.19?
AFS directories SET AS_RELEASE_ALWAYS but have not .release_folio.
next prev parent reply other threads:[~2025-12-08 20:13 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-08 19:03 [PATCH v2] fs: add NULL check in drop_buffers() to prevent null-ptr-deref Deepakkumar Karn
2025-12-08 19:30 ` Darrick J. Wong
2025-12-08 20:13 ` Deepakkumar Karn [this message]
2025-12-09 11:18 ` Jan Kara
2025-12-09 16:30 ` Deepak Karn
2025-12-10 9:55 ` Jan Kara
2025-12-10 15:29 ` Deepak Karn
2025-12-10 17:23 ` Jan Kara
2025-12-10 17:50 ` Deepak Karn
2025-12-11 9:15 ` Jan Kara
2025-12-11 12:50 ` Deepak Karn
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