6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Rik van Riel <riel@xxxxxxxxxxx>
[ 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: fee3ff99bc67 ("powerpc: Move arch independent ima kexec functions to drivers/of/kexec.c")
Suggested-by: Mike Rappoport <rppt@xxxxxxxxxx>
Signed-off-by: Rik van Riel <riel@xxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230817135558.67274c83@xxxxxxxxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/x86/kernel/setup.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 892609cde4a20..804a252382da7 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -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;
--
2.40.1
