[GIT PULL] memblock fixes for v6.5-rc4

[GIT PULL] memblock fixes for v6.5-rc4

[Mike Rapoport]

Hi Linus,

The following changes since commit 6eaae198076080886b9e7d57f4ae06fa782f90ef:

  Linux 6.5-rc3 (2023-07-23 15:24:10 -0700)

are available in the Git repository at:

  https://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock.git tags/fixes-2023-07-27

for you to fetch changes up to 9e46e4dcd9d6cd88342b028dbfa5f4fb7483d39c:

  mm,memblock: reset memblock.reserved to system init state to prevent UAF (2023-07-24 08:52:56 +0300)

----------------------------------------------------------------
memblock: reset memblock.reserved to system init state to prevent UAF

A call to memblock_free() or memblock_phys_free() issued after memblock
data is discarded will result in use after free in
memblock_isolate_range().

When CONFIG_KASAN is enabled, this will cause a panic early in boot.
Without CONFIG_KASAN, there is a chance that memblock_isolate_range() might
scribble on memory that is now in use by somebody else.

Avoid those issues by making sure that memblock_discard points
memblock.reserved.regions back at the static buffer.

If memblock_free() or memblock_phys_free() is called after memblock memory
is discarded, that will print a warning in memblock_remove_region().

----------------------------------------------------------------
Rik van Riel (1):
      mm,memblock: reset memblock.reserved to system init state to prevent UAF

 mm/memblock.c | 4 ++++
 1 file changed, 4 insertions(+)

-- 
Sincerely yours,
Mike.

Re: [GIT PULL] memblock fixes for v6.5-rc4

[Linus Torvalds]

On Wed, 26 Jul 2023 at 21:59, Mike Rapoport <rppt@kernel.org> wrote:
>
> memblock: reset memblock.reserved to system init state to prevent UAF
> [..]

The merge message shouldn't just be a repeat of the commit message.

I ended up cutting it down a bit, but would prefer to just get a
concise summary rather than the repeat of the message for the fix.

              Linus

Re: [GIT PULL] memblock fixes for v6.5-rc4

[pr-tracker-bot]

The pull request you sent on Thu, 27 Jul 2023 07:58:31 +0300:

> https://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock.git tags/fixes-2023-07-27

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/379e66711b33f9fdc0513daee6cf3dd8d2f6f435

Thank you!

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