FAILED: patch "[PATCH] binfmt_misc: restore write access when removing an entry" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x db1856ea9196cf6e015d12199a34c0b9313c7bfa
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026080512-motto-postwar-7c00@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From db1856ea9196cf6e015d12199a34c0b9313c7bfa Mon Sep 17 00:00:00 2001
From: Christian Brauner <[email protected]>
Date: Fri, 10 Jul 2026 11:33:02 +0200
Subject: [PATCH] binfmt_misc: restore write access when removing an entry

Registering an entry with the MISC_FMT_OPEN_FILE flag opens the
interpreter via open_exec() which denies write access to it for as
long as the entry exists. Removing the entry closes the interpreter
file via filp_close() but never restores write access, leaving the
inode's i_writecount permanently negative. Opening the interpreter
for writing keeps failing with ETXTBSY long after the entry is gone
until the inode is evicted from the inode cache.

Commit 90f601b497d7 ("binfmt_misc: restore write access before
closing files opened by open_exec()") fixed the same imbalance in the
error path of bm_register_write() but the actual removal path has
been leaking the write denial since the introduction of the flag.

Restore write access in put_binfmt_handler() before closing the
interpreter file.

Link: https://patch.msgid.link/[email protected]
Fixes: 948b701a607f ("binfmt_misc: add persistent opened binary handler for containers")
Cc: [email protected]
Signed-off-by: Christian Brauner (Amutable) <[email protected]>

diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index 47aeb2b68d3e..adab06d18550 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -162,8 +162,10 @@ static Node *get_binfmt_handler(struct binfmt_misc *misc,
 static void put_binfmt_handler(Node *e)
 {
 	if (refcount_dec_and_test(&e->users)) {
-		if (e->flags & MISC_FMT_OPEN_FILE)
+		if (e->flags & MISC_FMT_OPEN_FILE) {
+			exe_file_allow_write_access(e->interp_file);
 			filp_close(e->interp_file, NULL);
+		}
 		kfree(e);
 	}
 }