From 4f73c7d342d57d065bdbc0995cb56d8d1701b0c0 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Wed, 30 Apr 2014 09:31:47 -0400 Subject: cifs: fix potential races in cifs_revalidate_mapping The handling of the CIFS_INO_INVALID_MAPPING flag is racy. It's possible for two tasks to attempt to revalidate the mapping at the same time. The first sees that CIFS_INO_INVALID_MAPPING is set. It clears the flag and then calls invalidate_inode_pages2 to start shooting down the pagecache. While that's going on, another task checks the flag and sees that it's clear. It then ends up trusting the pagecache to satisfy a read when it shouldn't. Fix this by adding a bitlock to ensure that the clearing of the flag is atomic with respect to the actual cache invalidation. Also, move the other existing users of cifs_invalidate_mapping to use a new cifs_zap_mapping() function that just sets the INVALID_MAPPING bit and then uses the standard codepath to handle the invalidation. Signed-off-by: Jeff Layton Signed-off-by: Steve French --- fs/cifs/cifsfs.h | 1 + 1 file changed, 1 insertion(+) (limited to 'fs/cifs/cifsfs.h') diff --git a/fs/cifs/cifsfs.h b/fs/cifs/cifsfs.h index 63d51274dfbf..1bbe97c2a632 100644 --- a/fs/cifs/cifsfs.h +++ b/fs/cifs/cifsfs.h @@ -76,6 +76,7 @@ extern int cifs_revalidate_file(struct file *filp); extern int cifs_revalidate_dentry(struct dentry *); extern int cifs_invalidate_mapping(struct inode *inode); extern int cifs_revalidate_mapping(struct inode *inode); +extern int cifs_zap_mapping(struct inode *inode); extern int cifs_getattr(struct vfsmount *, struct dentry *, struct kstat *); extern int cifs_setattr(struct dentry *, struct iattr *); -- cgit v1.2.3-59-g8ed1b