Patch "fanotify: fix fsnotify_prepare_user_wait() failure" has been added to the 4.14-stable tree
This is a note to let you know that I've just added the patch titled
fanotify: fix fsnotify_prepare_user_wait() failure
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fanotify-fix-fsnotify_prepare_user_wait-failure.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.
Quoted 1 line
From
f37650f1c7c71cf5180b43229d13b421d81e7170Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <[email protected]>
Date: Mon, 30 Oct 2017 21:14:56 +0100
Subject: fanotify: fix fsnotify_prepare_user_wait() failure
From: Miklos Szeredi <[email protected]>
commit f37650f1c7c71cf5180b43229d13b421d81e7170 upstream.
If fsnotify_prepare_user_wait() fails, we leave the event on the notification list. Which will result in a warning in fsnotify_destroy_event() and later use-after-free.
Instead of adding a new helper to remove the event from the list in this case, I opted to move the prepare/finish up into fanotify_handle_event().
This will allow these to be moved further out into the generic code later, and perhaps let us move to non-sleeping RCU.
--- fs/notify/fanotify/fanotify.c | 33 ++++++++++++++++++++------------- 1 file changed, 20 insertions(+), 13 deletions(-)
fs/notify/fanotify/fanotify.c +20 -13
@@ -65,19 +65,8 @@ static int fanotify_get_response(structpr_debug ("%s: group=%p event=%p\n" , __func__, group, event); -/* -* fsnotify_prepare_user_wait() fails if we race with mark deletion. -* Just let the operation pass in that case. -*/ -if (!fsnotify_prepare_user_wait (iter_info)) { - event->response =FAN_ALLOW ; - goto out; - } -wait_event (group->fanotify_data.access_waitq, event->response); -fsnotify_finish_user_wait (iter_info); -out:/* userspace responded, convert to something usable */ switch (event->response) {case FAN_ALLOW :
@@ -212,9 +201,21 @@ static int fanotify_handle_event(structpr_debug ("%s: group=%p inode=%p mask=%x\n" , __func__, group, inode, mask); +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS +if (mask &FAN_ALL_PERM_EVENTS ) { +/* +* fsnotify_prepare_user_wait() fails if we race with mark +* deletion. Just let the operation pass in that case. +*/ +if (!fsnotify_prepare_user_wait (iter_info)) +return 0 ; + } +#endif + event =fanotify_alloc_event (inode, mask, data); + ret = -ENOMEM ;if (unlikely (!event)) -return -ENOMEM ; + goto finish; fsn_event = &event->fse; ret =fsnotify_add_event (group, fsn_event, fanotify_merge);
@@ -224,7 +225,8 @@ static int fanotify_handle_event(struct/* Our event wasn't used in the end. Free it. */ fsnotify_destroy_event (group, fsn_event); -return 0 ; + ret =0 ; + goto finish; }#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
@@ -233,6 +235,11 @@ static int fanotify_handle_event(struct iter_info);fsnotify_destroy_event (group, fsn_event); } +finish: +if (mask &FAN_ALL_PERM_EVENTS ) +fsnotify_finish_user_wait (iter_info); +#else +finish:#endif return ret; }
Patches currently in stable-queue which might be from [email protected] are
queue-4.14/fsnotify-clean-up-fsnotify_prepare-finish_user_wait.patch queue-4.14/fsnotify-fix-pinning-group-in-fsnotify_prepare_user_wait.patch queue-4.14/fanotify-fix-fsnotify_prepare_user_wait-failure.patch queue-4.14/fsnotify-pin-both-inode-and-vfsmount-mark.patch queue-4.14/ovl-put-upperdentry-if-ovl_check_origin-fails.patch