[SRU][Mantic][Lunar][PATCH 2/2] nf_tables: fix NULL pointer dereference in nft_expr_inner_parse()

[Bethany Jamison]

From: Xingyuan Mo <hdthky0 at gmail.com>

We should check whether the NFTA_EXPR_NAME netlink attribute is present
before accessing it, otherwise a null pointer deference error will occur.

Call Trace:
 <TASK>
 dump_stack_lvl+0x4f/0x90
 print_report+0x3f0/0x620
 kasan_report+0xcd/0x110
 __asan_load2+0x7d/0xa0
 nla_strcmp+0x2f/0x90
 __nft_expr_type_get+0x41/0xb0
 nft_expr_inner_parse+0xe3/0x200
 nft_inner_init+0x1be/0x2e0
 nf_tables_newrule+0x813/0x1230
 nfnetlink_rcv_batch+0xec3/0x1170
 nfnetlink_rcv+0x1e4/0x220
 netlink_unicast+0x34e/0x4b0
 netlink_sendmsg+0x45c/0x7e0
 __sys_sendto+0x355/0x370
 __x64_sys_sendto+0x84/0xa0
 do_syscall_64+0x3f/0x90
 entry_SYSCALL_64_after_hwframe+0x6e/0xd8

Fixes: 3a07327d10a0 ("netfilter: nft_inner: support for inner tunnel header matching")
Signed-off-by: Xingyuan Mo <hdthky0 at gmail.com>
Signed-off-by: Florian Westphal <fw at strlen.de>
(cherry picked from commit 505ce0630ad5d31185695f8a29dde8d29f28faa7)
CVE-2023-5972
Signed-off-by: Bethany Jamison <bethany.jamison at canonical.com>
---
 net/netfilter/nf_tables_api.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 976a9b763b9b..fd8c9389fb8d 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -3166,7 +3166,7 @@ int nft_expr_inner_parse(const struct nft_ctx *ctx, const struct nlattr *nla,
 	if (err < 0)
 		return err;
 
-	if (!tb[NFTA_EXPR_DATA])
+	if (!tb[NFTA_EXPR_DATA] || !tb[NFTA_EXPR_NAME])
 		return -EINVAL;
 
 	type = __nft_expr_type_get(ctx->family, tb[NFTA_EXPR_NAME]);
-- 
2.34.1