f2fs: avoid returning uninitialized value to userspace from f2fs_trim_fs()

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
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 2c1e60893ef27e66de15d7666239b458a00c1bc8..6b0850487aa23b902c5f99ae915d1cad33164ff0 100644 (file)
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1032,6 +1032,7 @@ int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
                                                range->len < sbi->blocksize)
                return -EINVAL;
 
+       cpc.trimmed = 0;
        if (end <= MAIN_BLKADDR(sbi))
                goto out;
 
@@ -1043,7 +1044,6 @@ int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
        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);