From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A264D15C82 for ; Mon, 5 Dec 2022 19:13:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 274CFC433C1; Mon, 5 Dec 2022 19:13:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1670267625; bh=ddOUfnrqpkL//QGOgwQwgPE2qRjog9BeZZWlOrVj6NU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oiLSWZXDvF9M2IHA31P0jCYvTcwo3RqvH5oDIAJ5XtdCRESGKusNjl8hABOGCLkTh 3dTRzwYCEv+/Ygd9AV8pgz2v3bV0RRQXHbEzPSMfc3rranavM/0bIH7qaSIqo6PMC3 MKwkcGKLRfW/qcfd6O+ZuS+bqDUfl8eFVIhK4YjU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot , Kuniyuki Iwashima , Jakub Kicinski , Ovidiu Panait Subject: [PATCH 4.9 55/62] tcp/udp: Fix memory leak in ipv6_renew_options(). Date: Mon, 5 Dec 2022 20:09:52 +0100 Message-Id: <20221205190800.156807515@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221205190758.073114639@linuxfoundation.org> References: <20221205190758.073114639@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Kuniyuki Iwashima commit 3c52c6bb831f6335c176a0fc7214e26f43adbd11 upstream. syzbot reported a memory leak [0] related to IPV6_ADDRFORM. The scenario is that while one thread is converting an IPv6 socket into IPv4 with IPV6_ADDRFORM, another thread calls do_ipv6_setsockopt() and allocates memory to inet6_sk(sk)->XXX after conversion. Then, the converted sk with (tcp|udp)_prot never frees the IPv6 resources, which inet6_destroy_sock() should have cleaned up. setsockopt(IPV6_ADDRFORM) setsockopt(IPV6_DSTOPTS) +-----------------------+ +----------------------+ - do_ipv6_setsockopt(sk, ...) - sockopt_lock_sock(sk) - do_ipv6_setsockopt(sk, ...) - lock_sock(sk) ^._ called via tcpv6_prot - WRITE_ONCE(sk->sk_prot, &tcp_prot) before WRITE_ONCE() - xchg(&np->opt, NULL) - txopt_put(opt) - sockopt_release_sock(sk) - release_sock(sk) - sockopt_lock_sock(sk) - lock_sock(sk) - ipv6_set_opt_hdr(sk, ...) - ipv6_update_options(sk, opt) - xchg(&inet6_sk(sk)->opt, opt) ^._ opt is never freed. - sockopt_release_sock(sk) - release_sock(sk) Since IPV6_DSTOPTS allocates options under lock_sock(), we can avoid this memory leak by testing whether sk_family is changed by IPV6_ADDRFORM after acquiring the lock. This issue exists from the initial commit between IPV6_ADDRFORM and IPV6_PKTOPTIONS. [0]: BUG: memory leak unreferenced object 0xffff888009ab9f80 (size 96): comm "syz-executor583", pid 328, jiffies 4294916198 (age 13.034s) hex dump (first 32 bytes): 01 00 00 00 48 00 00 00 08 00 00 00 00 00 00 00 ....H........... 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<000000002ee98ae1>] kmalloc include/linux/slab.h:605 [inline] [<000000002ee98ae1>] sock_kmalloc+0xb3/0x100 net/core/sock.c:2566 [<0000000065d7b698>] ipv6_renew_options+0x21e/0x10b0 net/ipv6/exthdrs.c:1318 [<00000000a8c756d7>] ipv6_set_opt_hdr net/ipv6/ipv6_sockglue.c:354 [inline] [<00000000a8c756d7>] do_ipv6_setsockopt.constprop.0+0x28b7/0x4350 net/ipv6/ipv6_sockglue.c:668 [<000000002854d204>] ipv6_setsockopt+0xdf/0x190 net/ipv6/ipv6_sockglue.c:1021 [<00000000e69fdcf8>] tcp_setsockopt+0x13b/0x2620 net/ipv4/tcp.c:3789 [<0000000090da4b9b>] __sys_setsockopt+0x239/0x620 net/socket.c:2252 [<00000000b10d192f>] __do_sys_setsockopt net/socket.c:2263 [inline] [<00000000b10d192f>] __se_sys_setsockopt net/socket.c:2260 [inline] [<00000000b10d192f>] __x64_sys_setsockopt+0xbe/0x160 net/socket.c:2260 [<000000000a80d7aa>] do_syscall_x64 arch/x86/entry/common.c:50 [inline] [<000000000a80d7aa>] do_syscall_64+0x38/0x90 arch/x86/entry/common.c:80 [<000000004562b5c6>] entry_SYSCALL_64_after_hwframe+0x63/0xcd Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot Signed-off-by: Kuniyuki Iwashima Signed-off-by: Jakub Kicinski Signed-off-by: Ovidiu Panait Signed-off-by: Greg Kroah-Hartman --- net/ipv6/ipv6_sockglue.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/net/ipv6/ipv6_sockglue.c +++ b/net/ipv6/ipv6_sockglue.c @@ -165,6 +165,12 @@ static int do_ipv6_setsockopt(struct soc rtnl_lock(); lock_sock(sk); + /* Another thread has converted the socket into IPv4 with + * IPV6_ADDRFORM concurrently. + */ + if (unlikely(sk->sk_family != AF_INET6)) + goto unlock; + switch (optname) { case IPV6_ADDRFORM: @@ -897,6 +903,7 @@ pref_skip_coa: break; } +unlock: release_sock(sk); if (needs_rtnl) rtnl_unlock();