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Wed, 11 Mar 2026 16:10:48 +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 5.15.y] binfmt_misc: restore write access before closing files opened by open_exec() Date: Wed, 11 Mar 2026 16:10:46 +0800 Message-Id: <20260311081046.1668003-1-rob_garcia@163.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:_____wD3v8OGI7FpmUFfAQ--.47091S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7Kw4fGF48tw1UurW8AF1DWrg_yoW8WF4Dpr W5K34UtrZIqryj9ayvyas8XF15G3Z7Gr12vr4kWw1xXF1rXrs0gFZ2g3yj93W0y397A3yF qF4rC3sYyryUAFJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07UxWrZUUUUU= X-Originating-IP: [60.247.85.88] X-CM-SenderInfo: 5uresw5dufxti6rwjhhfrp/xtbC5gmxHWmxI4mC7wAA3c X-Rspamd-Queue-Id: 208B1100007 X-Stat-Signature: 83zikfjqcaf7b8tzpmgmu9ytmqxte5i9 X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1773216663-332490 X-HE-Meta: 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 aTr8cGeg 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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 740dac1012ae..05c235309421 100644 --- a/fs/binfmt_misc.c +++ b/fs/binfmt_misc.c @@ -816,8 +816,10 @@ 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