linux-kernel - [PATCH net] ipv6: Fix potential uninit-value access in __ip6_make

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Date: Mon,  6 May 2024 23:11:29 +0900
From: Shigeru Yoshida <syoshida@...hat.com>
To: davem@...emloft.net,
	dsahern@...nel.org,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com
Cc: netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Shigeru Yoshida <syoshida@...hat.com>
Subject: [PATCH net] ipv6: Fix potential uninit-value access in __ip6_make_skb()

As it was done in commit fc1092f51567 ("ipv4: Fix uninit-value access in
__ip_make_skb()") for IPv4, check FLOWI_FLAG_KNOWN_NH on fl6->flowi6_flags
instead of testing HDRINCL on the socket to avoid a race condition which
causes uninit-value access.

Fixes: ea30388baebc ("ipv6: Fix an uninit variable access bug in __ip6_make_skb()")
Signed-off-by: Shigeru Yoshida <syoshida@...hat.com>
---
 net/ipv6/ip6_output.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index b9dd3a66e423..fa2937732665 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1933,7 +1933,7 @@ struct sk_buff *__ip6_make_skb(struct sock *sk,
 		u8 icmp6_type;
 
 		if (sk->sk_socket->type == SOCK_RAW &&
-		   !inet_test_bit(HDRINCL, sk))
+		   !(fl6->flowi6_flags & FLOWI_FLAG_KNOWN_NH))
 			icmp6_type = fl6->fl6_icmp_type;
 		else
 			icmp6_type = icmp6_hdr(skb)->icmp6_type;
-- 
2.44.0