[ 14/83] cifs: Do not lookup hashed negative dentry in cifs_atomic_open
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2012-11-22 21:51:27
Also in:
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3.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sachin Prabhu <redacted> commit 3798f47aa276b332c30da499cb4df4577e2f8872 upstream. We do not need to lookup a hashed negative directory since we have already revalidated it before and have found it to be fine. This also prevents a crash in cifs_lookup() when it attempts to rehash the already hashed negative lookup dentry. The patch has been tested using the reproducer at https://bugzilla.redhat.com/show_bug.cgi?id=867344#c28 Reported-by: Vit Zahradka <redacted> Signed-off-by: Sachin Prabhu <redacted> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- fs/cifs/dir.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c@@ -392,7 +392,16 @@ cifs_atomic_open(struct inode *inode, st * in network traffic in the other paths. */ if (!(oflags & O_CREAT)) { - struct dentry *res = cifs_lookup(inode, direntry, 0); + struct dentry *res; + + /* + * Check for hashed negative dentry. We have already revalidated + * the dentry and it is fine. No need to perform another lookup. + */ + if (!d_unhashed(direntry)) + return -ENOENT; + + res = cifs_lookup(inode, direntry, 0); if (IS_ERR(res)) return PTR_ERR(res);