cifs: Fix some error pointers handling detected by static checker

* extract_hostname() and extract_sharename() never return NULL, so
  use IS_ERR() instead of IS_ERR_OR_NULL() in cifs_find_swn_reg(). If
  any of these functions return an error, then return an error pointer
  instead of NULL.
* Change cifs_find_swn_reg() function to always return a valid pointer
  or an error pointer, instead of returning NULL if the registration
  is not found.
* Finally update cifs_find_swn_reg() callers to check for -EEXIST
  instead of NULL.
* In cifs_get_swn_reg() the swnreg idr mutex was not unlocked in the
  error path of cifs_find_swn_reg() call.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Samuel Cabrero <scabrero@suse.de>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/cifs/cifs_swn.c b/fs/cifs/cifs_swn.c
index a172769c239f9c724981064796c8364e8efde97e..69b7571010a62f8b82ea0ba9216c30b2d1cb1dc8 100644 (file)
--- a/fs/cifs/cifs_swn.c
+++ b/fs/cifs/cifs_swn.c
@@ -259,24 +259,24 @@ static struct cifs_swn_reg *cifs_find_swn_reg(struct cifs_tcon *tcon)
        const char *net_name;
 
        net_name = extract_hostname(tcon->treeName);
-       if (IS_ERR_OR_NULL(net_name)) {
+       if (IS_ERR(net_name)) {
                int ret;
 
                ret = PTR_ERR(net_name);
                cifs_dbg(VFS, "%s: failed to extract host name from target '%s': %d\n",
                                __func__, tcon->treeName, ret);
-               return NULL;
+               return ERR_PTR(-EINVAL);
        }
 
        share_name = extract_sharename(tcon->treeName);
-       if (IS_ERR_OR_NULL(share_name)) {
+       if (IS_ERR(share_name)) {
                int ret;
 
                ret = PTR_ERR(net_name);
                cifs_dbg(VFS, "%s: failed to extract share name from target '%s': %d\n",
                                __func__, tcon->treeName, ret);
                kfree(net_name);
-               return NULL;
+               return ERR_PTR(-EINVAL);
        }
 
        idr_for_each_entry(&cifs_swnreg_idr, swnreg, id) {
@@ -299,7 +299,7 @@ static struct cifs_swn_reg *cifs_find_swn_reg(struct cifs_tcon *tcon)
        kfree(net_name);
        kfree(share_name);
 
-       return NULL;
+       return ERR_PTR(-EEXIST);
 }
 
 /*
@@ -315,12 +315,13 @@ static struct cifs_swn_reg *cifs_get_swn_reg(struct cifs_tcon *tcon)
 
        /* Check if we are already registered for this network and share names */
        reg = cifs_find_swn_reg(tcon);
-       if (IS_ERR(reg)) {
-               return reg;
-       } else if (reg != NULL) {
+       if (!IS_ERR(reg)) {
                kref_get(&reg->ref_count);
                mutex_unlock(&cifs_swnreg_idr_mutex);
                return reg;
+       } else if (PTR_ERR(reg) != -EEXIST) {
+               mutex_unlock(&cifs_swnreg_idr_mutex);
+               return reg;
        }
 
        reg = kmalloc(sizeof(struct cifs_swn_reg), GFP_ATOMIC);
@@ -630,9 +631,9 @@ int cifs_swn_unregister(struct cifs_tcon *tcon)
        mutex_lock(&cifs_swnreg_idr_mutex);
 
        swnreg = cifs_find_swn_reg(tcon);
-       if (swnreg == NULL) {
+       if (IS_ERR(swnreg)) {
                mutex_unlock(&cifs_swnreg_idr_mutex);
-               return -EEXIST;
+               return PTR_ERR(swnreg);
        }
 
        mutex_unlock(&cifs_swnreg_idr_mutex);