From 967ac8af4475ce45474800709b12137aa7634c77 Mon Sep 17 00:00:00 2001 From: Haogang Chen Date: Mon, 28 May 2012 14:21:55 -0400 Subject: [PATCH] ext4: fix potential integer overflow in alloc_flex_gd() In alloc_flex_gd(), when flexbg_size is large, kmalloc size would overflow and flex_gd->groups would point to a buffer smaller than expected, causing OOB accesses when it is used. Note that in ext4_resize_fs(), flexbg_size is calculated using sbi->s_log_groups_per_flex, which is read from the disk and only bounded to [1, 31]. The patch returns NULL for too large flexbg_size. Reviewed-by: Eric Sandeen Signed-off-by: Haogang Chen Signed-off-by: "Theodore Ts'o" Cc: stable@kernel.org --- fs/ext4/resize.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c index a58ce7c507ae..05c7979226e5 100644 --- a/fs/ext4/resize.c +++ b/fs/ext4/resize.c @@ -161,6 +161,8 @@ static struct ext4_new_flex_group_data *alloc_flex_gd(unsigned long flexbg_size) if (flex_gd == NULL) goto out3; + if (flexbg_size >= UINT_MAX / sizeof(struct ext4_new_flex_group_data)) + goto out2; flex_gd->count = flexbg_size; flex_gd->groups = kmalloc(sizeof(struct ext4_new_group_data) * -- 2.20.1