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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: 54a611b605 ("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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.