ext4: potential crash on allocation error in ext4_alloc_flex_bg_array()
If sbi->s_flex_groups_allocated is zero and the first allocation fails
then this code will crash. The problem is that "i--" will set "i" to
-1 but when we compare "i >= sbi->s_flex_groups_allocated" then the -1
is type promoted to unsigned and becomes UINT_MAX. Since UINT_MAX
is more than zero, the condition is true so we call kvfree(new_groups[-1]).
The loop will carry on freeing invalid memory until it crashes.
Fixes: 7c990728b99e ("ext4: fix potential race between s_flex_groups online resizing and access")
Reviewed-by: Suraj Jitindar Singh <firstname.lastname@example.org>
Signed-off-by: Dan Carpenter <email@example.com>
Signed-off-by: Theodore Ts'o <firstname.lastname@example.org>
1 file changed