Commit 967ac8af authored May 28, 2012 by Haogang Chen Committed by Theodore Ts'o May 28, 2012

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 <sandeen@redhat.com>
Signed-off-by: Haogang Chen <haogangchen@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org

parent 9d99012f

fs/ext4/resize.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -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) *

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