[PATCH 3.18 18/84] f2fs: avoid returning uninitialized value to userspace from f2fs_trim_fs()

[Greg Kroah-Hartman]

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

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

From: Jan Kara <jack@xxxxxxx>

commit 9bd27ae4aafc9bfee6c8791f7d801ea16cc5622b upstream.

If user specifies too low end sector for trimming, f2fs_trim_fs() will
use uninitialized value as a number of trimmed blocks and returns it to
userspace. Initialize number of trimmed blocks early to avoid the
problem.

Coverity-id: 1248809
Signed-off-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1004,6 +1004,7 @@ int f2fs_trim_fs(struct f2fs_sb_info *sb
 						range->len < sbi->blocksize)
 		return -EINVAL;
 
+	cpc.trimmed = 0;
 	if (end <= MAIN_BLKADDR(sbi))
 		goto out;
 
@@ -1015,7 +1016,6 @@ int f2fs_trim_fs(struct f2fs_sb_info *sb
 	cpc.trim_start = start_segno;
 	cpc.trim_end = end_segno;
 	cpc.trim_minlen = range->minlen >> sbi->log_blocksize;
-	cpc.trimmed = 0;
 
 	/* do checkpoint to issue discard commands safely */
 	write_checkpoint(sbi, &cpc);


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