[CIFS] fix oops on second mount to same server when null auth is used

When a share is mounted using no username, cifs_mount sets
volume_info.username as a NULL pointer, and the sesInfo userName as an
empty string. The volume_info.username is passed to a couple of other
functions to see if there is an existing unc or tcp connection that can
be used. These functions assume that the username will be a valid
string that can be passed to strncmp. If the pointer is NULL, then the
kernel will oops if there's an existing session to which the string
can be compared.

This patch changes cifs_mount to set volume_info.username to an empty
string in this situation, which prevents the oops and should make it
so that the comparison to other null auth sessions match.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

diff --git a/fs/cifs/CHANGES b/fs/cifs/CHANGES
index 53629b8bc8a8b58ee74aa8e5cc9eb9e1f8d25778..64dd22239b21b4a7181b6c719ae091b76fc7b30d 100644 (file)
--- a/fs/cifs/CHANGES
+++ b/fs/cifs/CHANGES
@@ -1,5 +1,6 @@
 Version 1.52
 ------------
+Fix oops on second mount to server when null auth is used.
 
 Version 1.51
 ------------

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 380ee9991f204f3b827df31410fe9859be9753ea..1102160f6661069e725345642f4af2c7439fe6fa 100644 (file)
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1790,7 +1790,7 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
 
        if (volume_info.nullauth) {
                cFYI(1, ("null user"));
-               volume_info.username = NULL;
+               volume_info.username = "";
        } else if (volume_info.username) {
                /* BB fixme parse for domain name here */
                cFYI(1, ("Username: %s", volume_info.username));