Liam R. Howlett 955a923d28 maple_tree: fix mas_empty_area_rev() null pointer dereference
Currently the code calls mas_start() followed by mas_data_end() if the
maple state is MA_START, but mas_start() may return with the maple state
node == NULL.  This will lead to a null pointer dereference when checking
information in the NULL node, which is done in mas_data_end().

Avoid setting the offset if there is no node by waiting until after the
maple state is checked for an empty or single entry state.

A user could trigger the events to cause a kernel oops by unmapping all
vmas to produce an empty maple tree, then mapping a vma that would cause
the scenario described above.

Link: https://lkml.kernel.org/r/20240422203349.2418465-1-Liam.Howlett@oracle.com
Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reported-by: Marius Fleischer <fleischermarius@gmail.com>
Closes: https://lore.kernel.org/lkml/CAJg=8jyuSxDL6XvqEXY_66M20psRK2J53oBTP+fjV5xpW2-R6w@mail.gmail.com/
Link: https://lore.kernel.org/lkml/CAJg=8jyuSxDL6XvqEXY_66M20psRK2J53oBTP+fjV5xpW2-R6w@mail.gmail.com/
Tested-by: Marius Fleischer <fleischermarius@gmail.com>
Tested-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-05-05 17:28:05 -07:00
..
2024-01-19 11:59:11 -08:00
2024-02-01 13:06:40 +01:00
2018-08-16 12:14:42 -07:00
2023-11-03 07:08:36 -10:00
2021-01-21 14:06:00 -07:00
2022-03-07 12:48:35 -07:00
2021-08-19 09:02:55 +09:00
2023-02-02 22:50:01 -08:00
2023-02-02 22:50:01 -08:00
2021-01-03 20:05:18 -05:00
2023-03-19 10:02:04 -07:00
2022-03-07 12:48:35 -07:00
2022-04-29 14:38:01 -07:00
2022-10-03 14:03:21 -07:00
2024-03-11 09:38:17 -07:00
2021-08-19 09:02:55 +09:00
2024-02-12 10:35:40 -06:00
2024-03-23 08:43:21 -07:00
2021-07-08 11:48:20 -07:00
2023-08-21 13:46:25 -07:00
2023-04-17 18:01:23 +02:00
2021-07-08 11:48:20 -07:00
2023-10-16 12:44:06 -04:00
2023-08-24 16:20:18 -07:00
2023-10-16 12:44:06 -04:00
2024-03-14 10:58:27 -07:00
2018-10-16 13:45:44 +02:00
2022-10-03 17:34:32 -07:00
2021-07-08 11:48:20 -07:00
2024-02-15 12:17:28 -05:00
2022-06-03 10:34:34 -07:00
2024-02-20 20:47:32 -08:00
2021-06-18 11:43:09 +02:00
2021-07-08 11:48:20 -07:00
2022-01-20 08:52:54 +02:00
2024-02-22 10:24:48 -08:00