From: Eric Dumazet <edumazet@google.com> stable inclusion from stable-v5.10.232 commit a771f349c95d3397636861a0a6462d4a7a7ecb25 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBEAPI CVE: CVE-2024-56642 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... ------------------------------------------------- [ Upstream commit b04d86fff66b15c07505d226431f808c15b1703c ] syzbot found [1] that after blamed commit, ub->ubsock->sk was NULL when attempting the atomic_dec() : atomic_dec(&tipc_net(sock_net(ub->ubsock->sk))->wq_count); Fix this by caching the tipc_net pointer. [1] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] PREEMPT SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037] CPU: 0 UID: 0 PID: 5896 Comm: kworker/0:3 Not tainted 6.13.0-rc1-next-20241203-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Workqueue: events cleanup_bearer RIP: 0010:read_pnet include/net/net_namespace.h:387 [inline] RIP: 0010:sock_net include/net/sock.h:655 [inline] RIP: 0010:cleanup_bearer+0x1f7/0x280 net/tipc/udp_media.c:820 Code: 18 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 3c f7 99 f6 48 8b 1b 48 83 c3 30 e8 f0 e4 60 00 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 74 08 48 89 df e8 1a f7 99 f6 49 83 c7 e8 48 8b 1b RSP: 0018:ffffc9000410fb70 EFLAGS: 00010206 RAX: 0000000000000006 RBX: 0000000000000030 RCX: ffff88802fe45a00 RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffffc9000410f900 RBP: ffff88807e1f0908 R08: ffffc9000410f907 R09: 1ffff92000821f20 R10: dffffc0000000000 R11: fffff52000821f21 R12: ffff888031d19980 R13: dffffc0000000000 R14: dffffc0000000000 R15: ffff88807e1f0918 FS: 0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000556ca050b000 CR3: 0000000031c0c000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Fixes: 6a2fa13312e5 ("tipc: Fix use-after-free of kernel socket in cleanup_bearer().") Reported-by: syzbot+46aa5474f179dacd1a3b@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/67508b5f.050a0220.17bd51.0070.GAE@google.com/... Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Link: https://patch.msgid.link/20241204170548.4152658-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Liu Jian <liujian56@huawei.com> --- net/tipc/udp_media.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/tipc/udp_media.c b/net/tipc/udp_media.c index d54b5c1d3c83..25e733919131 100644 --- a/net/tipc/udp_media.c +++ b/net/tipc/udp_media.c @@ -803,6 +803,7 @@ static void cleanup_bearer(struct work_struct *work) { struct udp_bearer *ub = container_of(work, struct udp_bearer, work); struct udp_replicast *rcast, *tmp; + struct tipc_net *tn; list_for_each_entry_safe(rcast, tmp, &ub->rcast.list, list) { dst_cache_destroy(&rcast->dst_cache); @@ -810,10 +811,14 @@ static void cleanup_bearer(struct work_struct *work) kfree_rcu(rcast, rcu); } + tn = tipc_net(sock_net(ub->ubsock->sk)); + dst_cache_destroy(&ub->rcast.dst_cache); udp_tunnel_sock_release(ub->ubsock); + + /* Note: could use a call_rcu() to avoid another synchronize_net() */ synchronize_net(); - atomic_dec(&tipc_net(sock_net(ub->ubsock->sk))->wq_count); + atomic_dec(&tn->wq_count); kfree(ub); } -- 2.34.1