ext4: set goal start correctly in ext4_mb_normalize_request

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: ext4: set goal start correctly in ext4_mb_normalize_request We need to set ac_g_ex to notify the goal start used in ext4_mb_find_by_goal. Set ac_g_ex instead of ac_f_ex in ext4_mb_normalize_request. Besides we should assure goal start is in range [first_data_block, blocks_count) as ext4_mb_initialize_context does. [ Added a check to make sure size is less than ar->pright; otherwise we could end up passing an underflowed value of ar->pright - size to ext4_get_group_no_and_offset(), which will trigger a BUG_ON later on. - TYT ]

References

• https://git.kernel.org/stable/c/2479bb6cbdb4d56b807bbe5229e3e26a6f1f4530
• https://git.kernel.org/stable/c/390eee955d4de4662db5e3e9e9a9eae020432cb7
• https://git.kernel.org/stable/c/cee78217a7ae72d11c2e21e1a5263b8044489823
• https://git.kernel.org/stable/c/3ca3005b502ca8ea87d6a344323b179b48c4e4a3
• https://git.kernel.org/stable/c/bc4a3e1d07a86ae5845321d371190244acacb2f2
• https://git.kernel.org/stable/c/c6bee8970075b256fc1b07bf4873049219380818
• https://git.kernel.org/stable/c/abb330ffaa3a0ae7ce632e28c9260b461c01f19f
• https://git.kernel.org/stable/c/b07ffe6927c75d99af534d685282ea188d9f71a6