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fsnotify: pin both inode and vfsmount mark

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We may fail to pin one of the marks in fsnotify_prepare_user_wait() when
dropping the srcu read lock, resulting in use after free at the next
iteration.

Solution is to store both marks in iter_info instead of just the one we'll
be sending the event for.

Reviewed-by: Amir Goldstein <[email protected]>
Signed-off-by: Miklos Szeredi <[email protected]>
Fixes: 9385a84d7e ("fsnotify: Pass fsnotify_iter_info into handle_event handler")
Cc: <[email protected]> # v4.12
Signed-off-by: Jan Kara <[email protected]>
This commit is contained in:
Miklos Szeredi 2017-10-30 21:14:55 +01:00 • committed by Jan Kara
commit 0d6ec079d6
1 changed files with 7 additions and 3 deletions
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10
fs/notify/fsnotify.c
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@ -335,6 +335,13 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
struct fsnotify_mark, obj_list);
vfsmount_group = vfsmount_mark->group;
}
/*
* Need to protect both marks against freeing so that we can
* continue iteration from this place, regardless of which mark
* we actually happen to send an event for.
*/
iter_info.inode_mark = inode_mark;
iter_info.vfsmount_mark = vfsmount_mark;
if (inode_group && vfsmount_group) {
int cmp = fsnotify_compare_groups(inode_group,
@ -348,9 +355,6 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
}
}
iter_info.inode_mark = inode_mark;
iter_info.vfsmount_mark = vfsmount_mark;
ret = send_to_group(to_tell, inode_mark, vfsmount_mark, mask,
data, data_is, cookie, file_name,
&iter_info);