From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 7EF20FBF6 for ; Mon, 15 May 2023 17:50:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D70FAC4339B; Mon, 15 May 2023 17:50:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1684173015; bh=8KyMxfRAxcejXhbZXZZfXZJqWe5Lh/LKOML+lzsbDSI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hDRZ8LG9LCVneJmspHa+WLtfOXc0u9+Yg/LZ/4g/X73MPo3i9vSsPetISdWbgxggu xd25bCX5K3c6YcvEiqEAjL00EjHxf8g//rWSD9gWvgWhjpYhHnqGgJkQWO8gMncTY9 axkygD8QDWcoSHEawFMY6TOnxKWd1iVnzKT8AdQg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+4a06d4373fd52f0b2f9c@syzkaller.appspotmail.com, Amir Goldstein , Jan Kara Subject: [PATCH 5.10 340/381] inotify: Avoid reporting event with invalid wd Date: Mon, 15 May 2023 18:29:51 +0200 Message-Id: <20230515161752.212195368@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230515161736.775969473@linuxfoundation.org> References: <20230515161736.775969473@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Jan Kara commit c915d8f5918bea7c3962b09b8884ca128bfd9b0c upstream. When inotify_freeing_mark() races with inotify_handle_inode_event() it can happen that inotify_handle_inode_event() sees that i_mark->wd got already reset to -1 and reports this value to userspace which can confuse the inotify listener. Avoid the problem by validating that wd is sensible (and pretend the mark got removed before the event got generated otherwise). CC: stable@vger.kernel.org Fixes: 7e790dd5fc93 ("inotify: fix error paths in inotify_update_watch") Message-Id: <20230424163219.9250-1-jack@suse.cz> Reported-by: syzbot+4a06d4373fd52f0b2f9c@syzkaller.appspotmail.com Reviewed-by: Amir Goldstein Signed-off-by: Jan Kara Signed-off-by: Greg Kroah-Hartman --- fs/notify/inotify/inotify_fsnotify.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) --- a/fs/notify/inotify/inotify_fsnotify.c +++ b/fs/notify/inotify/inotify_fsnotify.c @@ -64,7 +64,7 @@ int inotify_handle_inode_event(struct fs struct fsnotify_event *fsn_event; struct fsnotify_group *group = inode_mark->group; int ret; - int len = 0; + int len = 0, wd; int alloc_len = sizeof(struct inotify_event_info); struct mem_cgroup *old_memcg; @@ -80,6 +80,13 @@ int inotify_handle_inode_event(struct fs fsn_mark); /* + * We can be racing with mark being detached. Don't report event with + * invalid wd. + */ + wd = READ_ONCE(i_mark->wd); + if (wd == -1) + return 0; + /* * Whoever is interested in the event, pays for the allocation. Do not * trigger OOM killer in the target monitoring memcg as it may have * security repercussion. @@ -109,7 +116,7 @@ int inotify_handle_inode_event(struct fs fsn_event = &event->fse; fsnotify_init_event(fsn_event, 0); event->mask = mask; - event->wd = i_mark->wd; + event->wd = wd; event->sync_cookie = cookie; event->name_len = len; if (len)