From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9B31546C82A; Thu, 20 Aug 2026 17:57:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787248629; cv=none; b=khekTfVzvK6TOPA6aoVgJm/yujT2RLNhrxexVhfo7u9MjscdGS07szHgLDBCcKg5szCZkx9wvy+GD5ZoKJ1Zxt2ABE2blJP2Z+Kd4K9uhmci9EDydqbyTHIF+uFS7Xf51fsXzwTTp+FCH6SjiG4ZHTIZduJKXrd9xfexe3Mf9u8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787248629; c=relaxed/simple; bh=KJ2TGzPlpH6q9Tx/xUbs5b/COaZjPv3pGE4dizdZdIg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=U4SoCiqba+AbC19lASeFscRxgyP05gFCHhvjsmZRinuDVU+MGRwoCYJn8tmvq0MtgIit+3OEPmBoRfff9clPhsVdRqyXZKOb+g0S+Dz+RQEZVyHk5y07ksW/2UbijmSAcBOWSPG/Gfp1MjooRl5/d1G/NWnzBnWcFo00hJX6dvs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=g5eyWsft; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="g5eyWsft" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E6B5E1F000E9; Thu, 20 Aug 2026 17:57:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787248628; bh=CHulttgJWJNfII4Uukkij9e8iIQIZNMfShVAwNWOoO0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=g5eyWsft+K6q/efa7rZuA+ZKn3UyiCccfUi6YLs64s9iUo3Y/j98ySMATF08hRvBv mfH0RgGNXv607MXwtd85cqTwLaFCjoGmvWAUAfT1yMZKuaxjhRDjJO9JB7gcufvEMp qUMidffbhF+l+YVs4U4iinAnPbZZeDpsoofHFE90= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Christian Brauner (Amutable)" Subject: [PATCH 6.1 294/303] binfmt_misc: use exe_file_deny_write_access() for the interpreter clone Date: Thu, 20 Aug 2026 16:57:10 +0200 Message-ID: <20260820145302.310840511@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260820145253.200766705@linuxfoundation.org> References: <20260820145253.200766705@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christian Brauner commit fa5990ca8fd917003e526036bcc50413edb9722c upstream. For MISC_FMT_OPEN_FILE entries load_misc_binary() clones the registered interpreter file and denies write access to the clone via plain deny_write_access(). The clone is installed as bprm->interpreter and later released by the exec machinery through exe_file_allow_write_access() which skips the i_writecount increment for files with FMODE_FSNOTIFY_HSM set. The deny and allow side can therefore come to different conclusions when pre-content watches are in play: if a pre-content watch is added to the interpreter after registration every subsequent exec through that entry takes a write denial on the clone that is never paired with a write allowance, driving the interpreter inode's i_writecount further down with each exec and leaving the interpreter unwritable even after the entry and all its users are gone. Take the write denial via exe_file_deny_write_access() so both sides of the pairing base their decision on the same file mode, and propagate failure instead of silently ignoring it: an interpreter that is concurrently open for writing now fails the exec with ETXTBSY, exactly like an interpreter freshly opened via open_exec() would. Link: https://patch.msgid.link/20260710-work-binfmt_misc-locking-v3-2-a162f7cb58d6@kernel.org Fixes: 0357ef03c94e ("fs: don't block write during exec on pre-content watched files") Cc: stable@vger.kernel.org Signed-off-by: Christian Brauner (Amutable) Signed-off-by: Greg Kroah-Hartman --- fs/binfmt_misc.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/fs/binfmt_misc.c +++ b/fs/binfmt_misc.c @@ -220,8 +220,14 @@ static int load_misc_binary(struct linux if (fmt->flags & MISC_FMT_OPEN_FILE) { interp_file = file_clone_open(fmt->interp_file); - if (!IS_ERR(interp_file)) - deny_write_access(interp_file); + if (!IS_ERR(interp_file)) { + int err = exe_file_deny_write_access(interp_file); + + if (err) { + fput(interp_file); + interp_file = ERR_PTR(err); + } + } } else { interp_file = open_exec(fmt->interpreter); }