coda: avoid NULL pointer dereference from a bad inode

Patch series "Coda updates for -next".

The following patch series contains some fixes for the Coda kernel module
I've had sitting around and were tested extensively in a development
version of the Coda kernel module that lives outside of the main kernel.

This patch (of 9):

Avoid accessing coda_inode_info from a dentry with a bad inode.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Jan Harkes <[email protected]>
Cc: Alex Shi <[email protected]>
Cc: Jing Yangyang <[email protected]>
Cc: Xin Tan <[email protected]>
Cc: Xiyu Yang <[email protected]>
Cc: Zeal Robot <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 9 insertions, 4 deletions

diff --git a/fs/coda/dir.c b/fs/coda/dir.c
index d69989c1bac3..3fd085009f26 100644
--- a/fs/coda/dir.c
+++ b/fs/coda/dir.c
@@ -499,15 +499,20 @@ out:
  */
 static int coda_dentry_delete(const struct dentry * dentry)
 {
-	int flags;
+	struct inode *inode;
+	struct coda_inode_info *cii;
 
 	if (d_really_is_negative(dentry)) 
 		return 0;
 
-	flags = (ITOC(d_inode(dentry))->c_flags) & C_PURGE;
-	if (is_bad_inode(d_inode(dentry)) || flags) {
+	inode = d_inode(dentry);
+	if (!inode || is_bad_inode(inode))
 		return 1;
-	}
+
+	cii = ITOC(inode);
+	if (cii->c_flags & C_PURGE)
+		return 1;
+
 	return 0;
 }