IMA: update ima_counts_put

- As ima_counts_put() may be called after the inode has been freed,
verify that the inode is not NULL, before dereferencing it.

- Maintain the IMA file counters in may_open() properly, decrementing
any counter increments on subsequent errors.

Reported-by: Ciprian Docan <docan@eden.rutgers.edu>
Reported-by: J.R. Okajima <hooanon05@yahoo.co.jp>
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 5 insertions, 1 deletions

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 4732f5e5d127..b85e61bcf246 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -249,7 +249,11 @@ void ima_counts_put(struct path *path, int mask)
         struct inode *inode = path->dentry->d_inode;
         struct ima_iint_cache *iint;
 
-        if (!ima_initialized || !S_ISREG(inode->i_mode))
+        /* The inode may already have been freed, freeing the iint
+         * with it. Verify the inode is not NULL before dereferencing
+         * it.
+         */
+        if (!ima_initialized || !inode || !S_ISREG(inode->i_mode))
                 return;
         iint = ima_iint_find_insert_get(inode);
         if (!iint)