linux-kernel - [PATCH 4.8 55/85] f2fs: fix overflow due to condition check order

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Date:   Wed,  4 Jan 2017 21:47:40 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jaegeuk Kim <jaegeuk@...nel.org>
Subject: [PATCH 4.8 55/85] f2fs: fix overflow due to condition check order

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

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

From: Jaegeuk Kim <jaegeuk@...nel.org>

commit e87f7329bbd6760c2acc4f1eb423362b08851a71 upstream.

In the last ilen case, i was already increased, resulting in accessing out-
of-boundary entry of do_replace and blkaddr.
Fix to check ilen first to exit the loop.

Fixes: 2aa8fbb9693020 ("f2fs: refactor __exchange_data_block for speed up")
Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/f2fs/file.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -970,7 +970,7 @@ static int __clone_blkaddrs(struct inode
 				new_size = (dst + i) << PAGE_SHIFT;
 				if (dst_inode->i_size < new_size)
 					f2fs_i_size_write(dst_inode, new_size);
-			} while ((do_replace[i] || blkaddr[i] == NULL_ADDR) && --ilen);
+			} while (--ilen && (do_replace[i] || blkaddr[i] == NULL_ADDR));
 
 			f2fs_put_dnode(&dn);
 		} else {