From: Jeff Layton <jlayton@redhat.com>
Date: Wed, 10 Nov 2010 15:19:10 +0000 (-0500)
Subject: cifs: fix potential use-after-free in cifs_oplock_break_put
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=ebe2e91e000c59aed0300d81815f451c85e0bda6;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git

cifs: fix potential use-after-free in cifs_oplock_break_put

cfile may very well be freed after the cifsFileInfo_put. Make sure we
have a valid pointer to the superblock for cifs_sb_deactive.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
---

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 06c3e83fa387..b857ce5db775 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2271,8 +2271,10 @@ void cifs_oplock_break_get(struct cifsFileInfo *cfile)
 
 void cifs_oplock_break_put(struct cifsFileInfo *cfile)
 {
+	struct super_block *sb = cfile->dentry->d_sb;
+
 	cifsFileInfo_put(cfile);
-	cifs_sb_deactive(cfile->dentry->d_sb);
+	cifs_sb_deactive(sb);
 }
 
 const struct address_space_operations cifs_addr_ops = {