From: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Date: Tue, 19 Jun 2018 14:54:38 +0800
Patch-mainline: 4.18
Git-commit: 22883ddc66df402f2fbc37fe1f4d2779238e4b2d
Subject: [PATCH 6/6] btrfs: fix invalid-free in btrfs_extent_same
References: bsc#1127498

If this condition ((BTRFS_I(src)->flags & BTRFS_INODE_NODATASUM) !=
		   (BTRFS_I(dst)->flags & BTRFS_INODE_NODATASUM))
is hit, we will go to free the uninitialized cmp.src_pages and
cmp.dst_pages.

Fixes: 67b07bd4bec5 ("Btrfs: reuse cmp workspace in EXTENT_SAME ioctl")
Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
---
 fs/btrfs/ioctl.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 2bc1d60d235c..f380e0ae7a6b 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3287,7 +3287,7 @@ static int btrfs_extent_same(struct inode *src, u64 loff, u64 olen,
 		ret = btrfs_extent_same_range(src, loff, BTRFS_MAX_DEDUPE_LEN,
 					      dst, dst_loff, &cmp);
 		if (ret)
-			goto out_unlock;
+			goto out_free;
 
 		loff += BTRFS_MAX_DEDUPE_LEN;
 		dst_loff += BTRFS_MAX_DEDUPE_LEN;
@@ -3297,16 +3297,16 @@ static int btrfs_extent_same(struct inode *src, u64 loff, u64 olen,
 		ret = btrfs_extent_same_range(src, loff, tail_len, dst,
 					      dst_loff, &cmp);
 
+out_free:
+	kvfree(cmp.src_pages);
+	kvfree(cmp.dst_pages);
+
 out_unlock:
 	if (same_inode)
 		inode_unlock(src);
 	else
 		btrfs_double_inode_unlock(src, dst);
 
-out_free:
-	kvfree(cmp.src_pages);
-	kvfree(cmp.dst_pages);
-
 	return ret;
 }
 
-- 
2.19.0