tree 705fba5830e9face7c833b5801f9d7577a3c5ef3
parent 3f9ee50d8bc200e1d89b46183d2f66759f3c7970
author Peng Zhang <zhangpeng.00@bytedance.com> 1681896985 +0800
committer Shuo Yang <gshuoy@google.com> 1721327571 +0000

maple_tree: fix allocation in mas_sparse_area()

commit 29ad6bb313487370f9dfe5441fc8982593b6384e upstream.

In the case of reverse allocation, mas->index and mas->last do not point
to the correct allocation range, which will cause users to get incorrect
allocation results, so fix it.  If the user does not use it in a specific
way, this bug will not be triggered.

This is a bug, but only VMA uses it now, the way VMA is used now will
not trigger it.  There is a possibility that a user will trigger it in
the future.

Also re-check whether the size is still satisfied after the lower bound
was increased, which is a corner case and is incorrect in previous
versions.

BUG=b/346513880
TEST=presubmit
RELEASE_NOTE=None

cos-patch: security-moderate
Link: https://lkml.kernel.org/r/20230419093625.99201-1-zhangpeng.00@bytedance.com
Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Change-Id: I82eae1b133e12539195a6281810054f8b937178e
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Shuo Yang <gshuoy@google.com>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/76504
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Kevin Berry <kpberry@google.com>