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[CIFS] Prevent OOPs when mounting with remote prefixpath. 

Fixes OOPs with message 'kernel BUG at fs/cifs/cifs_dfs_ref.c:274!'.
Checks if the prefixpath in an accesible while we are still in cifs_mount
and fails with reporting a error if we can't access the prefixpath

Should fix Samba bugs 6086 and 5861 and kernel bug 12192

Signed-off-by: Igor Mammedov <niallain@gmail.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
This commit is contained in:
Igor Mammedov 2009-02-10 14:10:26 +03:00 committed by Steve French
parent e1f81c8a41
commit e4cce94c9c
3 changed files with 48 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
fs/cifs/cifsproto.h
View File

@ -42,6 +42,7 @@ extern void _FreeXid(unsigned int);
#define GetXid() (int)_GetXid(); cFYI(1,("CIFS VFS: in %s as Xid: %d with uid: %d",__func__, xid,current_fsuid()));
#define FreeXid(curr_xid) {_FreeXid(curr_xid); cFYI(1,("CIFS VFS: leaving %s (xid = %d) rc = %d",__func__,curr_xid,(int)rc));}
extern char *build_path_from_dentry(struct dentry *);
extern char *cifs_build_path_to_root(struct cifs_sb_info *cifs_sb);
extern char *build_wildcard_path_from_dentry(struct dentry *direntry);
/* extern void renew_parental_timestamps(struct dentry *direntry);*/
extern int SendReceive(const unsigned int /* xid */ , struct cifsSesInfo *,

45
fs/cifs/connect.c
View File

@ -2180,6 +2180,33 @@ static void setup_cifs_sb(struct smb_vol *pvolume_info,
"mount option supported"));
}
static int
is_path_accessible(int xid, struct cifsTconInfo *tcon,
struct cifs_sb_info *cifs_sb, const char *full_path)
{
int rc;
__u64 inode_num;
FILE_ALL_INFO *pfile_info;
rc = CIFSGetSrvInodeNumber(xid, tcon, full_path, &inode_num,
cifs_sb->local_nls,
cifs_sb->mnt_cifs_flags &
CIFS_MOUNT_MAP_SPECIAL_CHR);
if (rc != -EOPNOTSUPP)
return rc;
pfile_info = kmalloc(sizeof(FILE_ALL_INFO), GFP_KERNEL);
if (pfile_info == NULL)
return -ENOMEM;
rc = CIFSSMBQPathInfo(xid, tcon, full_path, pfile_info,
0 /* not legacy */, cifs_sb->local_nls,
cifs_sb->mnt_cifs_flags &
CIFS_MOUNT_MAP_SPECIAL_CHR);
kfree(pfile_info);
return rc;
}
int
cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
char *mount_data, const char *devname)
@ -2190,6 +2217,7 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
struct cifsSesInfo *pSesInfo = NULL;
struct cifsTconInfo *tcon = NULL;
struct TCP_Server_Info *srvTcp = NULL;
char *full_path;
xid = GetXid();
@ -2426,6 +2454,23 @@ mount_fail_check:
cifs_sb->rsize = min(cifs_sb->rsize,
(tcon->ses->server->maxBuf - MAX_CIFS_HDR_SIZE));
if (!rc && cifs_sb->prepathlen) {
/* build_path_to_root works only when we have a valid tcon */
full_path = cifs_build_path_to_root(cifs_sb);
if (full_path == NULL) {
rc = -ENOMEM;
goto mount_fail_check;
}
rc = is_path_accessible(xid, tcon, cifs_sb, full_path);
if (rc) {
cERROR(1, ("Path %s in not accessible: %d",
full_path, rc));
kfree(full_path);
goto mount_fail_check;
}
kfree(full_path);
}
/* volume_info->password is freed above when existing session found
(in which case it is not needed anymore) but when new sesion is created
the password ptr is put in the new session structure (in which case the

4
fs/cifs/inode.c
View File

@ -621,7 +621,7 @@ static const struct inode_operations cifs_ipc_inode_ops = {
.lookup = cifs_lookup,
};
static char *build_path_to_root(struct cifs_sb_info *cifs_sb)
char *cifs_build_path_to_root(struct cifs_sb_info *cifs_sb)
{
int pplen = cifs_sb->prepathlen;
int dfsplen;
@ -678,7 +678,7 @@ struct inode *cifs_iget(struct super_block *sb, unsigned long ino)
return inode;
cifs_sb = CIFS_SB(inode->i_sb);
full_path = build_path_to_root(cifs_sb);
full_path = cifs_build_path_to_root(cifs_sb);
if (full_path == NULL)
return ERR_PTR(-ENOMEM);