From aec51758ce10a9c847a62a48a168f8c804c6e053 Mon Sep 17 00:00:00 2001 From: Jerry Lee Date: Sun, 6 Aug 2017 01:18:31 -0400 Subject: [PATCH] ext4: fix overflow caused by missing cast in ext4_resize_fs() On a 32-bit platform, the value of n_blcoks_count may be wrong during the file system is resized to size larger than 2^32 blocks. This may caused the superblock being corrupted with zero blocks count. Fixes: 1c6bd7173d66 Signed-off-by: Jerry Lee Signed-off-by: Theodore Ts'o Cc: stable@vger.kernel.org # 3.7+ --- fs/ext4/resize.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c index c3ed9021b781..035cd3f4785e 100644 --- a/fs/ext4/resize.c +++ b/fs/ext4/resize.c @@ -1927,7 +1927,8 @@ retry: n_desc_blocks = o_desc_blocks + le16_to_cpu(es->s_reserved_gdt_blocks); n_group = n_desc_blocks * EXT4_DESC_PER_BLOCK(sb); - n_blocks_count = n_group * EXT4_BLOCKS_PER_GROUP(sb); + n_blocks_count = (ext4_fsblk_t)n_group * + EXT4_BLOCKS_PER_GROUP(sb); n_group--; /* set to last group number */ } -- 2.20.1