Re: FAILED: patch "[PATCH] mm,ima,kexec,of: use memblock_free_late from" failed to apply to 5.15-stable tree

[Mike Rapoport <rppt@kernel.org>]

Hi Greg,

On Sat, Aug 26, 2023 at 07:43:42PM +0200, gregkh@linuxfoundation.org wrote:
> 
> The patch below does not apply to the 5.15-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.

This version applies to 5.15-stable:

From 582bd7a69533d8b3b5ad3e1df93cb382d25407d8 Mon Sep 17 00:00:00 2001
From: Rik van Riel <riel@surriel.com>
Date: Thu, 17 Aug 2023 13:57:59 -0400
Subject: [PATCH] mm,ima,kexec,of: use memblock_free_late from
 ima_free_kexec_buffer

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 issue.

Fixes: fee3ff99bc67 ("powerpc: Move arch independent ima kexec functions to drivers/of/kexec.c")
Cc: stable@kernel.org
Signed-off-by: Rik van Riel <riel@surriel.com>
Suggested-by: Mike Rappoport <rppt@kernel.org>
Link: https://lore.kernel.org/r/20230817135759.0888e5ef@imladris.surriel.com
Signed-off-by: Rob Herring <robh@kernel.org>
(cherry picked from commit f0362a253606e2031f8d61c74195d4d6556e12a4)
Signed-off-by: Mike Rappoport (IBM) <rppt@kernel.org>
---
 drivers/of/kexec.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c
index 52bb68fb2216..3a07cc58e7d7 100644
--- a/drivers/of/kexec.c
+++ b/drivers/of/kexec.c
@@ -187,8 +187,8 @@ int ima_free_kexec_buffer(void)
 	if (ret)
 		return ret;
 
-	return memblock_free(addr, size);
-
+	memblock_free_late(addr, size);
+	return 0;
 }
 
 /**
-- 
2.39.2