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Thu, 05 Mar 2026 10:35:02 +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 6.6.y] binfmt_misc: restore write access before closing files opened by open_exec() Date: Thu, 5 Mar 2026 10:35:01 +0800 Message-Id: <20260305023501.4003943-1-rob_garcia@163.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:PSgvCgBn393V66hpNnfqUA--.606S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7Kw4fGF48tw1UurW8AF1DWrg_yoW8WF4Dpr W5K34UKFZIqryj9a1kCas8XF15G3Z7Gr12vr4DWw1fXrn5Xrs0gFZ2g3yj93W0y397ArWF vF4Fk3sYyryUAFJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07UoCJQUUUUU= X-Originating-IP: [60.247.85.88] X-CM-SenderInfo: 5uresw5dufxti6rwjhhfrp/xtbDARa0IGmo69acswAA3Q X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 04219100003 X-Stat-Signature: cezys3rxy9sddbnemkio4pjabbipscar X-Rspam-User: X-HE-Tag: 1772678314-460887 X-HE-Meta: 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 XaB09JoK 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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 cf5ed5cd4102..a45b5ba12a9c 100644 --- a/fs/binfmt_misc.c +++ b/fs/binfmt_misc.c @@ -815,8 +815,10 @@ 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