This is a note to let you know that I've just added the patch titled ipv4: check for NULL idev in ip_route_use_hint() to the 6.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ipv4-check-for-null-idev-in-ip_route_use_hint.patch and it can be found in the queue-6.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit bb33e22d6ea1fa900f6610b73743044037674e9a Author: Eric Dumazet <edumazet@xxxxxxxxxx> Date: Sun Apr 21 18:43:26 2024 +0000 ipv4: check for NULL idev in ip_route_use_hint() [ Upstream commit 58a4c9b1e5a3e53c9148e80b90e1e43897ce77d1 ] syzbot was able to trigger a NULL deref in fib_validate_source() in an old tree [1]. It appears the bug exists in latest trees. All calls to __in_dev_get_rcu() must be checked for a NULL result. [1] general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 2 PID: 3257 Comm: syz-executor.3 Not tainted 5.10.0-syzkaller #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 RIP: 0010:fib_validate_source+0xbf/0x15a0 net/ipv4/fib_frontend.c:425 Code: 18 f2 f2 f2 f2 42 c7 44 20 23 f3 f3 f3 f3 48 89 44 24 78 42 c6 44 20 27 f3 e8 5d 88 48 fc 4c 89 e8 48 c1 e8 03 48 89 44 24 18 <42> 80 3c 20 00 74 08 4c 89 ef e8 d2 15 98 fc 48 89 5c 24 10 41 bf RSP: 0018:ffffc900015fee40 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff88800f7a4000 RCX: ffff88800f4f90c0 RDX: 0000000000000000 RSI: 0000000004001eac RDI: ffff8880160c64c0 RBP: ffffc900015ff060 R08: 0000000000000000 R09: ffff88800f7a4000 R10: 0000000000000002 R11: ffff88800f4f90c0 R12: dffffc0000000000 R13: 0000000000000000 R14: 0000000000000000 R15: ffff88800f7a4000 FS: 00007f938acfe6c0(0000) GS:ffff888058c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f938acddd58 CR3: 000000001248e000 CR4: 0000000000352ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ip_route_use_hint+0x410/0x9b0 net/ipv4/route.c:2231 ip_rcv_finish_core+0x2c4/0x1a30 net/ipv4/ip_input.c:327 ip_list_rcv_finish net/ipv4/ip_input.c:612 [inline] ip_sublist_rcv+0x3ed/0xe50 net/ipv4/ip_input.c:638 ip_list_rcv+0x422/0x470 net/ipv4/ip_input.c:673 __netif_receive_skb_list_ptype net/core/dev.c:5572 [inline] __netif_receive_skb_list_core+0x6b1/0x890 net/core/dev.c:5620 __netif_receive_skb_list net/core/dev.c:5672 [inline] netif_receive_skb_list_internal+0x9f9/0xdc0 net/core/dev.c:5764 netif_receive_skb_list+0x55/0x3e0 net/core/dev.c:5816 xdp_recv_frames net/bpf/test_run.c:257 [inline] xdp_test_run_batch net/bpf/test_run.c:335 [inline] bpf_test_run_xdp_live+0x1818/0x1d00 net/bpf/test_run.c:363 bpf_prog_test_run_xdp+0x81f/0x1170 net/bpf/test_run.c:1376 bpf_prog_test_run+0x349/0x3c0 kernel/bpf/syscall.c:3736 __sys_bpf+0x45c/0x710 kernel/bpf/syscall.c:5115 __do_sys_bpf kernel/bpf/syscall.c:5201 [inline] __se_sys_bpf kernel/bpf/syscall.c:5199 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5199 Fixes: 02b24941619f ("ipv4: use dst hint for ipv4 list receive") Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx> Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx> Acked-by: Paolo Abeni <pabeni@xxxxxxxxxx> Link: https://lore.kernel.org/r/20240421184326.1704930-1-edumazet@xxxxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/ipv4/route.c b/net/ipv4/route.c index a0c687ff25987..6c0f1e347b855 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -2168,6 +2168,9 @@ int ip_route_use_hint(struct sk_buff *skb, __be32 daddr, __be32 saddr, int err = -EINVAL; u32 tag = 0; + if (!in_dev) + return -EINVAL; + if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr)) goto martian_source;