From: Jan Kara Date: Thu, 30 Oct 2014 14:52:57 +0000 (-0400) Subject: ext4: fix overflow when updating superblock backups after resize X-Git-Tag: v5.15~16940^2~9 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=9378c6768e4fca48971e7b6a9075bc006eda981d;p=platform%2Fkernel%2Flinux-starfive.git ext4: fix overflow when updating superblock backups after resize When there are no meta block groups update_backups() will compute the backup block in 32-bit arithmetics thus possibly overflowing the block number and corrupting the filesystem. OTOH filesystems without meta block groups larger than 16 TB should be rare. Fix the problem by doing the counting in 64-bit arithmetics. Coverity-id: 741252 CC: stable@vger.kernel.org Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o Reviewed-by: Lukas Czerner --- diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c index f298c60..ca45883 100644 --- a/fs/ext4/resize.c +++ b/fs/ext4/resize.c @@ -1081,7 +1081,7 @@ static void update_backups(struct super_block *sb, int blk_off, char *data, break; if (meta_bg == 0) - backup_block = group * bpg + blk_off; + backup_block = ((ext4_fsblk_t)group) * bpg + blk_off; else backup_block = (ext4_group_first_block_no(sb, group) + ext4_bg_has_super(sb, group));