linux-kernel - [PATCH 1/2] apparmor: Fix 8-byte alignment for initial dfa blob streams

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Message-ID: <20250531150822.135803-2-deller@kernel.org>
Date: Sat, 31 May 2025 17:08:21 +0200
From: deller@...nel.org
To: linux-kernel@...r.kernel.org,
	apparmor@...ts.ubuntu.com,
	John Johansen <john.johansen@...onical.com>,
	linux-security-module@...r.kernel.org
Cc: Helge Deller <deller@....de>,
	stable@...r.kernel.org
Subject: [PATCH 1/2] apparmor: Fix 8-byte alignment for initial dfa blob streams

From: Helge Deller <deller@....de>

The dfa blob stream for the aa_dfa_unpack() function is expected to be aligned
on a 8 byte boundary.

The static nulldfa_src[] and stacksplitdfa_src[] arrays store the inital
apparmor dfa blob streams, but since they are declared as an array-of-chars
the compiler and linker will only ensure a "char" (1-byte) alignment.

Add an __aligned(8) annotation to the arrays to tell the linker to always
align them on a 8-byte boundary. This avoids runtime warnings at startup on
alignment-sensitive platforms like parisc such as:

 Kernel: unaligned access to 0x7f2a584a in aa_dfa_unpack+0x124/0x788 (iir 0xca0109f)
 Kernel: unaligned access to 0x7f2a584e in aa_dfa_unpack+0x210/0x788 (iir 0xca8109c)
 Kernel: unaligned access to 0x7f2a586a in aa_dfa_unpack+0x278/0x788 (iir 0xcb01090)

Signed-off-by: Helge Deller <deller@....de>
Cc: stable@...r.kernel.org
---
 security/apparmor/lsm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 9b6c2f157f83..531bde29cccb 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -2149,12 +2149,12 @@ static int __init apparmor_nf_ip_init(void)
 __initcall(apparmor_nf_ip_init);
 #endif
 
-static char nulldfa_src[] = {
+static char nulldfa_src[] __aligned(8) = {
 	#include "nulldfa.in"
 };
 static struct aa_dfa *nulldfa;
 
-static char stacksplitdfa_src[] = {
+static char stacksplitdfa_src[] __aligned(8) = {
 	#include "stacksplitdfa.in"
 };
 struct aa_dfa *stacksplitdfa;
-- 
2.47.0