Unverified Commit 90f601b4 authored by Zilin Guan's avatar Zilin Guan Committed by Christian Brauner
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binfmt_misc: restore write access before closing files opened by open_exec() 



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: e7850f4d ("binfmt_misc: fix possible deadlock in bm_register_write")
Signed-off-by: default avatarZilin Guan <zilin@seu.edu.cn>
Link: https://patch.msgid.link/20251105022923.1813587-1-zilin@seu.edu.cn


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent c0140212

fs/binfmt_misc.c

+3 −1
Original line number Diff line number Diff line
@@ -837,8 +837,10 @@ static ssize_t bm_register_write(struct file *file, const char __user *buffer, 
	inode_unlock(d_inode(root));



	if (err) {

		if (f)

		if (f) {

			exe_file_allow_write_access(f);

			filp_close(f, NULL);

		}

		kfree(e);

		return err;

	}