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Wed, 04 Mar 2026 13:43:12 +0800 (CST) From: Robert Garcia To: stable@vger.kernel.org, Zilin Guan Cc: Christian Brauner , Alexander Viro , Robert Garcia , Jan Kara , Eric Biederman , Kees Cook , Andrew Morton , Helge Deller , Lior Ribak , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 6.12.y] binfmt_misc: restore write access before closing files opened by open_exec() Date: Wed, 4 Mar 2026 13:43:11 +0800 Message-Id: <20260304054311.108543-1-rob_garcia@163.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:_____wCn2vtvxqdp8eEYOA--.5674S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7Kw4fGF48tw1UurW8AF1DWrg_yoW8WF4Dpr W5K34UtrZ0qryj9aykAas8WF15G3Z7GrsFvr4kWw1fXF1rXrs0gFZ2g3yj93W8A397ArWF qF4rC3sYyryUAFJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07U4MKZUUUUU= X-Originating-IP: [60.247.85.88] X-CM-SenderInfo: 5uresw5dufxti6rwjhhfrp/xtbC5RISfWmnxnLEuAAA3e X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: AC8A640003 X-Stat-Signature: 7w1haabh5mzekfh7rrgqpao5tc7p8fa5 X-Rspam-User: X-HE-Tag: 1772603021-79475 X-HE-Meta: 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 DgZV0FY4 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Zilin Guan [ Upstream commit 90f601b497d76f40fa66795c3ecf625b6aced9fd ] bm_register_write() opens an executable file using open_exec(), which internally calls do_open_execat() and denies write access on the file to avoid modification while it is being executed. However, when an error occurs, bm_register_write() closes the file using filp_close() directly. This does not restore the write permission, which may cause subsequent write operations on the same file to fail. Fix this by calling exe_file_allow_write_access() before filp_close() to restore the write permission properly. Fixes: e7850f4d844e ("binfmt_misc: fix possible deadlock in bm_register_write") Signed-off-by: Zilin Guan Link: https://patch.msgid.link/20251105022923.1813587-1-zilin@seu.edu.cn Signed-off-by: Christian Brauner [ Use allow_write_access() instead of exe_file_allow_write_access() according to commit 0357ef03c94ef ("fs: don't block write during exec on pre-content watched files"). ] Signed-off-by: Robert Garcia --- fs/binfmt_misc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c index 6a3a16f91051..9fbff75e3faa 100644 --- a/fs/binfmt_misc.c +++ b/fs/binfmt_misc.c @@ -875,8 +875,10 @@ static ssize_t bm_register_write(struct file *file, const char __user *buffer, inode_unlock(d_inode(root)); if (err) { - if (f) + if (f) { + allow_write_access(f); filp_close(f, NULL); + } kfree(e); return err; } -- 2.34.1