4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Miklos Szeredi <mszer...@redhat.com>

commit e71b9dff0634edb127f449e076e883ef24a8c76c upstream.

Ima tries to call ->setxattr() on overlayfs dentry after having locked
underlying inode, which results in a deadlock.

Reported-by: Krisztian Litkey <k...@iki.fi>
Fixes: 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay and 
f_inode to the underlay")
Signed-off-by: Miklos Szeredi <mszer...@redhat.com>
Cc: Mimi Zohar <zo...@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 security/integrity/ima/ima_appraise.c |    4 ++--
 security/integrity/ima/ima_main.c     |    2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -190,7 +190,7 @@ int ima_appraise_measurement(enum ima_ho
 {
        static const char op[] = "appraise_data";
        char *cause = "unknown";
-       struct dentry *dentry = file->f_path.dentry;
+       struct dentry *dentry = file_dentry(file);
        struct inode *inode = d_backing_inode(dentry);
        enum integrity_status status = INTEGRITY_UNKNOWN;
        int rc = xattr_len, hash_start = 0;
@@ -295,7 +295,7 @@ out:
  */
 void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
 {
-       struct dentry *dentry = file->f_path.dentry;
+       struct dentry *dentry = file_dentry(file);
        int rc = 0;
 
        /* do not collect and update hash for digital signatures */
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -228,7 +228,7 @@ static int process_measurement(struct fi
        if ((action & IMA_APPRAISE_SUBMASK) ||
                    strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0)
                /* read 'security.ima' */
-               xattr_len = ima_read_xattr(file->f_path.dentry, &xattr_value);
+               xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
 
        hash_algo = ima_get_hash_algo(xattr_value, xattr_len);
 


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