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x86/mm, kexec, ima: Use memblock_free_late() from ima_free_kexec_buffer()

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[ Upstream commit 34cf99c250d5cd2530b93a57b0de31d3aaf8685b ]

The code calling ima_free_kexec_buffer() runs long after the memblock
allocator has already been torn down, potentially resulting in a use
after free in memblock_isolate_range().

With KASAN or KFENCE, this use after free will result in a BUG
from the idle task, and a subsequent kernel panic.

Switch ima_free_kexec_buffer() over to memblock_free_late() to avoid
that bug.

Fixes: fee3ff99bc ("powerpc: Move arch independent ima kexec functions to drivers/of/kexec.c")
Suggested-by: Mike Rappoport <rppt@kernel.org>
Signed-off-by: Rik van Riel <riel@surriel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230817135558.67274c83@imladris.surriel.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Rik van Riel 2023-08-17 13:55:58 -04:00 • committed by Greg Kroah-Hartman
parent 73be49248a
commit eef16bfdb2
1 changed files with 2 additions and 6 deletions
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8
arch/x86/kernel/setup.c
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@ -363,15 +363,11 @@ static void __init add_early_ima_buffer(u64 phys_addr)
#if defined(CONFIG_HAVE_IMA_KEXEC) && !defined(CONFIG_OF_FLATTREE)
int __init ima_free_kexec_buffer(void)
{
int rc;
if (!ima_kexec_buffer_size)
return -ENOENT;
rc = memblock_phys_free(ima_kexec_buffer_phys,
ima_kexec_buffer_size);
if (rc)
return rc;
memblock_free_late(ima_kexec_buffer_phys,
ima_kexec_buffer_size);
ima_kexec_buffer_phys = 0;
ima_kexec_buffer_size = 0;