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 2AC0C3803D7; Thu, 20 Aug 2026 17:43:16 +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=1787247797; cv=none; b=PYuUfJ2DFQqdJMFFJAY7MZx/fg7EM+tOkFi2zBiR4LSYRHLxUBaLM0NQdARX36nIe/SdLV8oi9IftTTni+8IaMlBHyNVEXAPK8I3RrTO48GXJaNDK8UNddKqwP7Vf+B7NfFVHnKTOhaoijz0O8JcmOT6ayTprdfAzm1GZPTbOq4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787247797; c=relaxed/simple; bh=3MTEO0H8p88uHcC5NINEMVB2RqVQLsFkwvp232MB7xw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=A5Plf/UKBFf4ZAAYT4PORVhabF5298DMwIgATgF30iKnVKR5lLnswZZMrJ/YKyoQ/pnQEMQY13xDwQLY5iDcfi1+O5Mcx1wmmIx6gIbrFkXXkltMzofRk6D2tb3IgWKsQsP4oQBXjcjUA7/B82hBLz97Y1r/MAG8OBk13L/KYpE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=p8MMAGBw; 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="p8MMAGBw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6398C1F000E9; Thu, 20 Aug 2026 17:43:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787247796; bh=4fmea4RpvRcVpep/+n07BlSmNAJcKSNcpQ6CJGzx3BI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=p8MMAGBwk5FGEi25jOhZWPeoiuGPEQkPrwvSBli3Ax72+5AB9n29ncp5ZSEItlYzj Sqd4Mt4BDsOcMAqoyjRO2mtK8pgwhS83wEX2iYCyQ/nIjHMxch6ZyrEWPpJ+Gx5sJe 6GH43YSUg4eSzo6Np2wQ6VTDaoJ6d8KDRzGQUD+4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Christian Brauner (Amutable)" Subject: [PATCH 6.6 165/166] binfmt_misc: use exe_file_deny_write_access() for the interpreter clone Date: Thu, 20 Aug 2026 16:57:04 +0200 Message-ID: <20260820145216.125192945@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260820145211.194104353@linuxfoundation.org> References: <20260820145211.194104353@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 6.6-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); }