From: Russell King <rmk+kernel@armlinux.org.uk>
Date: Tue, 4 Jun 2019 13:50:14 +0000 (+0100)
Subject: fs/adfs: super: fix use-after-free bug
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=5808b14a1f52554de612fee85ef517199855e310;p=linux.git

fs/adfs: super: fix use-after-free bug

Fix a use-after-free bug during filesystem initialisation, where we
access the disc record (which is stored in a buffer) after we have
released the buffer.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---

diff --git a/fs/adfs/super.c b/fs/adfs/super.c
index 2f81c1c297573..b1243433add71 100644
--- a/fs/adfs/super.c
+++ b/fs/adfs/super.c
@@ -378,6 +378,7 @@ static int adfs_fill_super(struct super_block *sb, void *data, int silent)
 	struct buffer_head *bh;
 	struct object_info root_obj;
 	unsigned char *b_data;
+	unsigned int blocksize;
 	struct adfs_sb_info *asb;
 	struct inode *root;
 	int ret = -EINVAL;
@@ -423,8 +424,10 @@ static int adfs_fill_super(struct super_block *sb, void *data, int silent)
 		goto error_badfs;
 	}
 
+	blocksize = 1 << dr->log2secsize;
 	brelse(bh);
-	if (sb_set_blocksize(sb, 1 << dr->log2secsize)) {
+
+	if (sb_set_blocksize(sb, blocksize)) {
 		bh = sb_bread(sb, ADFS_DISCRECORD / sb->s_blocksize);
 		if (!bh) {
 			adfs_msg(sb, KERN_ERR,