From: Tobias Stoeckmann <tobias@stoeckmann.org>
Date: Wed, 18 Sep 2024 19:47:48 +0000 (+0200)
Subject: libkmod: Avoid misaligned memory accesses
X-Git-Tag: v34~298
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4e65ba2a3dc7455a92cdadda2f5cffa9496c159c;p=thirdparty%2Fkmod.git

libkmod: Avoid misaligned memory accesses

ASAN incorrectly reports this as unaligned access if compiler
optimizes code. Since ASAN support is valued higher than this
kind of optimization, just copy these few bytes into a stack
variable and avoid false positives in tests.

Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Link: https://github.com/kmod-project/kmod/pull/147
Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>
---

diff --git a/libkmod/libkmod-signature.c b/libkmod/libkmod-signature.c
index c4af9789..9f2de23e 100644
--- a/libkmod/libkmod-signature.c
+++ b/libkmod/libkmod-signature.c
@@ -307,7 +307,7 @@ bool kmod_module_signature_info(const struct kmod_file *file, struct kmod_signat
 {
 	const char *mem;
 	off_t size;
-	const struct module_signature *modsig;
+	struct module_signature modsig;
 	size_t sig_len;
 
 	size = kmod_file_get_size(file);
@@ -321,21 +321,21 @@ bool kmod_module_signature_info(const struct kmod_file *file, struct kmod_signat
 	if (size < (off_t)sizeof(struct module_signature))
 		return false;
 	size -= sizeof(struct module_signature);
-	modsig = (struct module_signature *)(mem + size);
-	if (modsig->algo >= PKEY_ALGO__LAST ||
-			modsig->hash >= PKEY_HASH__LAST ||
-			modsig->id_type >= PKEY_ID_TYPE__LAST)
+	memcpy(&modsig, mem + size, sizeof(struct module_signature));
+	if (modsig.algo >= PKEY_ALGO__LAST ||
+			modsig.hash >= PKEY_HASH__LAST ||
+			modsig.id_type >= PKEY_ID_TYPE__LAST)
 		return false;
-	sig_len = be32toh(get_unaligned(&modsig->sig_len));
+	sig_len = be32toh(modsig.sig_len);
 	if (sig_len == 0 ||
-	    size < (int64_t)sig_len + modsig->signer_len + modsig->key_id_len)
+	    size < (int64_t)sig_len + modsig.signer_len + modsig.key_id_len)
 		return false;
 
-	switch (modsig->id_type) {
+	switch (modsig.id_type) {
 	case PKEY_ID_PKCS7:
-		return fill_pkcs7(mem, size, modsig, sig_len, sig_info);
+		return fill_pkcs7(mem, size, &modsig, sig_len, sig_info);
 	default:
-		return fill_default(mem, size, modsig, sig_len, sig_info);
+		return fill_default(mem, size, &modsig, sig_len, sig_info);
 	}
 }