udata: fix sigbus crash on sparc

Anatoly Pugachev reported crash on 'nft list tables' on sparc
and provided following gdb backtrace:

 Starting program: /opt/nft/sbin/nft list tables
 Program received signal SIGBUS, Bus error.
 0xfff8000100946490 in nftnl_udata_get_u32 (attr=0x10000106e30) at udata.c:127
 127             return *data;

We can't deref attr->value directly, it causes unaligned access.

Reported-by: Anatoly Pugachev <matorola@gmail.com>
Tested-by: Anatoly Pugachev <matorola@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>

1 files changed, 4 insertions, 2 deletions

diff --git a/src/udata.c b/src/udata.c
index b5a4729..9f17395 100644
--- a/src/udata.c
+++ b/src/udata.c
@@ -122,9 +122,11 @@ void *nftnl_udata_get(const struct nftnl_udata *attr)
 EXPORT_SYMBOL(nftnl_udata_get_u32);
 uint32_t nftnl_udata_get_u32(const struct nftnl_udata *attr)
 {
-	uint32_t *data = (uint32_t *)attr->value;
+	uint32_t data;
 
-	return *data;
+	memcpy(&data, attr->value, sizeof(data));
+
+	return data;
 }
 
 EXPORT_SYMBOL(nftnl_udata_next);