# \[PATCH v2\] CIPSO: Fix unaligned memory access in cipso\_v4\_gentag\_hdr

- From: Sergey Nazarov \<hidden\>
- Date: 2021-03-05 08:07:41 
- List: linux-security-module
- Page: https://ratatoskr.run/linux-security-module/2021/03/11197848
- Thread: https://ratatoskr.run/linux-security-module/2021/03/11197848/t.md

```text
We need to use put_unaligned when writing 32-bit DOI value
in cipso_v4_gentag_hdr to avoid unaligned memory access.

v2: unneeded type cast removed as Ondrej Mosnacek suggested.

Signed-off-by: Sergey Nazarov <redacted>
---
 net/ipv4/cipso_ipv4.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index 471d33a..6e59902 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -1162,7 +1162,7 @@ static void cipso_v4_gentag_hdr(const struct
cipso_v4_doi *doi_def,
 {
 	buf[0] = IPOPT_CIPSO;
 	buf[1] = CIPSO_V4_HDR_LEN + len;
-	*(__be32 *)&buf[2] = htonl(doi_def->doi);
+	put_unaligned_be32(doi_def->doi, &buf[2]);
 }
 
 /**
-- 
1.8.3.1


```