xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

cifs: fix potential races in cifs_revalidate_mapping

Browse Source 
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 <jlayton@poochiereds.net>
Signed-off-by: Steve French <smfrench@gmail.com>
This commit is contained in:
Jeff Layton
2014-04-30 09:31:47 -04:00
committed by Steve French
parent e284e53fde
commit 4f73c7d342
4 changed files with 49 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
fs/cifs/cifsfs.h
View File

@@ -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 *);