From: Andrew Morton <akpm@linux-foundation.org>
To: Tejas Bharambe <thbharam@gmail.com>
Cc: ocfs2-devel@lists.linux.dev, mark@fasheh.com, jlbec@evilplan.org,
joseph.qi@linux.alibaba.com, linux-kernel@vger.kernel.org,
syzbot+a49010a0e8fcdeea075f@syzkaller.appspotmail.com,
Tejas Bharambe <tejas.bharambe@outlook.com>,
stable@vger.kernel.org
Subject: Re: [PATCH v4] ocfs2: fix use-after-free in ocfs2_fault() when VM_FAULT_RETRY
Date: Fri, 3 Apr 2026 12:29:47 -0700 [thread overview]
Message-ID: <20260403122947.2afc337b5333fb1990a78a65@linux-foundation.org> (raw)
In-Reply-To: <20260403035333.136824-1-tejas.bharambe@outlook.com>
On Thu, 2 Apr 2026 20:53:33 -0700 Tejas Bharambe <thbharam@gmail.com> wrote:
> filemap_fault() may drop the mmap_lock before returning VM_FAULT_RETRY,
> as documented in mm/filemap.c:
>
> "If our return value has VM_FAULT_RETRY set, it's because the mmap_lock
> may be dropped before doing I/O or by lock_folio_maybe_drop_mmap()."
>
> When this happens, a concurrent munmap() can call remove_vma() and free
> the vm_area_struct via RCU. The saved 'vma' pointer in ocfs2_fault() then
> becomes a dangling pointer, and the subsequent trace_ocfs2_fault() call
> dereferences it -- a use-after-free.
>
> Fix this by saving the inode reference before calling filemap_fault(),
> and removing vma from the trace event. The inode remains valid across
> the lock drop since the file is still open, so the trace can fire in
> all cases without dereferencing the potentially freed vma.
There's one question from the Sashiko AI reviewbot:
https://sashiko.dev/#/patchset/20260403035333.136824-1-tejas.bharambe@outlook.com
next prev parent reply other threads:[~2026-04-03 19:29 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-03 3:53 [PATCH v4] ocfs2: fix use-after-free in ocfs2_fault() when VM_FAULT_RETRY Tejas Bharambe
2026-04-03 19:29 ` Andrew Morton [this message]
2026-04-05 0:30 ` tejas bharambe
2026-04-05 0:50 ` Andrew Morton
2026-04-08 3:50 ` tejas bharambe
2026-04-08 5:46 ` Joseph Qi
2026-04-08 20:12 ` Andrew Morton
2026-04-10 8:01 ` Tejas Bharambe
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