From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 962FF3A3E9C; Wed, 20 May 2026 17:39:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779298757; cv=none; b=UImCazf8n4MgDW9RTU8aft6optmUQfRY/Sg53WtehQ6JWoygmIToTsdph6MNbYKEQSS3P1M8V0Nl7AIc42q1mWvaJlbNWXSMSnlbe3BrmEHQvzz/xvNP5CdSC8WiBensYoeSDbme/cxcaa4jA0fuW/6OkiI06GVmwJQxTX0tZCI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779298757; c=relaxed/simple; bh=Lx1RH290B0JxtkQJ9GZJC29pxrDNFjSo517mHKspjxE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=KclQ1qCHorYDTpwBdQZ5fVpC4Fk370jh5Yd64Ws4hz1gquPmR2kv8U7aYRbl8clHSS4dvDKnqq8voT6srs1PUhKkMSl7PnYrCKHWCJ6hHr5E8BT9Oq4RI2O3DoD54BcPk1d7TZysUiakpCprBQunjdiGvYCG4bcHh6CiJ9MwJz4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=YcF1eUeD; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="YcF1eUeD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EEC731F000E9; Wed, 20 May 2026 17:39:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1779298756; bh=6KG+inLnMN6irLM3BkcNr/WI/kpNDhq5UA7Gy/zwpLw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=YcF1eUeDpwOR7kAIy9iSzWgkKmUg3npIIjvzrjxrE9+3yGmtf7A33SOLviIGksiOh oIFYM07KiM715ogeWlEOAE8HQByuaNGm0DDWGLrC+rFo1jsBda90FOtCQ27PuxtvGO U6FJU/2ixOoPbAoH1L9NrRwbhjVMVcsyMAsJlufc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kuniyuki Iwashima , Michal Luczaj , Martin KaFai Lau , Sasha Levin Subject: [PATCH 6.18 490/957] bpf, sockmap: Take state lock for af_unix iter Date: Wed, 20 May 2026 18:16:13 +0200 Message-ID: <20260520162145.151925884@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260520162134.554764788@linuxfoundation.org> References: <20260520162134.554764788@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Michal Luczaj [ Upstream commit 64c2f93fc3254d3bf5de4445fb732ee5c451edb6 ] When a BPF iterator program updates a sockmap, there is a race condition in unix_stream_bpf_update_proto() where the `peer` pointer can become stale[1] during a state transition TCP_ESTABLISHED -> TCP_CLOSE. CPU0 bpf CPU1 close -------- ---------- // unix_stream_bpf_update_proto() sk_pair = unix_peer(sk) if (unlikely(!sk_pair)) return -EINVAL; // unix_release_sock() skpair = unix_peer(sk); unix_peer(sk) = NULL; sock_put(skpair) sock_hold(sk_pair) // UaF More practically, this fix guarantees that the iterator program is consistently provided with a unix socket that remains stable during iterator execution. [1]: BUG: KASAN: slab-use-after-free in unix_stream_bpf_update_proto+0x155/0x490 Write of size 4 at addr ffff8881178c9a00 by task test_progs/2231 Call Trace: dump_stack_lvl+0x5d/0x80 print_report+0x170/0x4f3 kasan_report+0xe4/0x1c0 kasan_check_range+0x125/0x200 unix_stream_bpf_update_proto+0x155/0x490 sock_map_link+0x71c/0xec0 sock_map_update_common+0xbc/0x600 sock_map_update_elem+0x19a/0x1f0 bpf_prog_bbbf56096cdd4f01_selective_dump_unix+0x20c/0x217 bpf_iter_run_prog+0x21e/0xae0 bpf_iter_unix_seq_show+0x1e0/0x2a0 bpf_seq_read+0x42c/0x10d0 vfs_read+0x171/0xb20 ksys_read+0xff/0x200 do_syscall_64+0xf7/0x5e0 entry_SYSCALL_64_after_hwframe+0x76/0x7e Allocated by task 2236: kasan_save_stack+0x30/0x50 kasan_save_track+0x14/0x30 __kasan_slab_alloc+0x63/0x80 kmem_cache_alloc_noprof+0x1d5/0x680 sk_prot_alloc+0x59/0x210 sk_alloc+0x34/0x470 unix_create1+0x86/0x8a0 unix_stream_connect+0x318/0x15b0 __sys_connect+0xfd/0x130 __x64_sys_connect+0x72/0xd0 do_syscall_64+0xf7/0x5e0 entry_SYSCALL_64_after_hwframe+0x76/0x7e Freed by task 2236: kasan_save_stack+0x30/0x50 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3b/0x70 __kasan_slab_free+0x47/0x70 kmem_cache_free+0x11c/0x590 __sk_destruct+0x432/0x6e0 unix_release_sock+0x9b3/0xf60 unix_release+0x8a/0xf0 __sock_release+0xb0/0x270 sock_close+0x18/0x20 __fput+0x36e/0xac0 fput_close_sync+0xe5/0x1a0 __x64_sys_close+0x7d/0xd0 do_syscall_64+0xf7/0x5e0 entry_SYSCALL_64_after_hwframe+0x76/0x7e Fixes: 2c860a43dd77 ("bpf: af_unix: Implement BPF iterator for UNIX domain socket.") Suggested-by: Kuniyuki Iwashima Signed-off-by: Michal Luczaj Signed-off-by: Martin KaFai Lau Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260414-unix-proto-update-null-ptr-deref-v4-5-2af6fe97918e@rbox.co Signed-off-by: Sasha Levin --- net/unix/af_unix.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index cf022252d521c..33ed8ecb556dd 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -3779,6 +3779,7 @@ static int bpf_iter_unix_seq_show(struct seq_file *seq, void *v) return 0; lock_sock(sk); + unix_state_lock(sk); if (unlikely(sock_flag(sk, SOCK_DEAD))) { ret = SEQ_SKIP; @@ -3790,6 +3791,7 @@ static int bpf_iter_unix_seq_show(struct seq_file *seq, void *v) prog = bpf_iter_get_info(&meta, false); ret = unix_prog_seq_show(prog, &meta, v, uid); unlock: + unix_state_unlock(sk); release_sock(sk); return ret; } -- 2.53.0