6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet edumazet@google.com
[ Upstream commit d375b98e0248980681e5e56b712026174d617198 ]
syzbot pointed out [1] that NEXTHDR_FRAGMENT handling is broken.
Reading frag_off can only be done if we pulled enough bytes to skb->head. Currently we might access garbage.
[1] BUG: KMSAN: uninit-value in ip6_tnl_parse_tlv_enc_lim+0x94f/0xbb0 ip6_tnl_parse_tlv_enc_lim+0x94f/0xbb0 ipxip6_tnl_xmit net/ipv6/ip6_tunnel.c:1326 [inline] ip6_tnl_start_xmit+0xab2/0x1a70 net/ipv6/ip6_tunnel.c:1432 __netdev_start_xmit include/linux/netdevice.h:4940 [inline] netdev_start_xmit include/linux/netdevice.h:4954 [inline] xmit_one net/core/dev.c:3548 [inline] dev_hard_start_xmit+0x247/0xa10 net/core/dev.c:3564 __dev_queue_xmit+0x33b8/0x5130 net/core/dev.c:4349 dev_queue_xmit include/linux/netdevice.h:3134 [inline] neigh_connected_output+0x569/0x660 net/core/neighbour.c:1592 neigh_output include/net/neighbour.h:542 [inline] ip6_finish_output2+0x23a9/0x2b30 net/ipv6/ip6_output.c:137 ip6_finish_output+0x855/0x12b0 net/ipv6/ip6_output.c:222 NF_HOOK_COND include/linux/netfilter.h:303 [inline] ip6_output+0x323/0x610 net/ipv6/ip6_output.c:243 dst_output include/net/dst.h:451 [inline] ip6_local_out+0xe9/0x140 net/ipv6/output_core.c:155 ip6_send_skb net/ipv6/ip6_output.c:1952 [inline] ip6_push_pending_frames+0x1f9/0x560 net/ipv6/ip6_output.c:1972 rawv6_push_pending_frames+0xbe8/0xdf0 net/ipv6/raw.c:582 rawv6_sendmsg+0x2b66/0x2e70 net/ipv6/raw.c:920 inet_sendmsg+0x105/0x190 net/ipv4/af_inet.c:847 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg net/socket.c:745 [inline] ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638 __sys_sendmsg net/socket.c:2667 [inline] __do_sys_sendmsg net/socket.c:2676 [inline] __se_sys_sendmsg net/socket.c:2674 [inline] __x64_sys_sendmsg+0x307/0x490 net/socket.c:2674 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b
Uninit was created at: slab_post_alloc_hook+0x129/0xa70 mm/slab.h:768 slab_alloc_node mm/slub.c:3478 [inline] __kmem_cache_alloc_node+0x5c9/0x970 mm/slub.c:3517 __do_kmalloc_node mm/slab_common.c:1006 [inline] __kmalloc_node_track_caller+0x118/0x3c0 mm/slab_common.c:1027 kmalloc_reserve+0x249/0x4a0 net/core/skbuff.c:582 pskb_expand_head+0x226/0x1a00 net/core/skbuff.c:2098 __pskb_pull_tail+0x13b/0x2310 net/core/skbuff.c:2655 pskb_may_pull_reason include/linux/skbuff.h:2673 [inline] pskb_may_pull include/linux/skbuff.h:2681 [inline] ip6_tnl_parse_tlv_enc_lim+0x901/0xbb0 net/ipv6/ip6_tunnel.c:408 ipxip6_tnl_xmit net/ipv6/ip6_tunnel.c:1326 [inline] ip6_tnl_start_xmit+0xab2/0x1a70 net/ipv6/ip6_tunnel.c:1432 __netdev_start_xmit include/linux/netdevice.h:4940 [inline] netdev_start_xmit include/linux/netdevice.h:4954 [inline] xmit_one net/core/dev.c:3548 [inline] dev_hard_start_xmit+0x247/0xa10 net/core/dev.c:3564 __dev_queue_xmit+0x33b8/0x5130 net/core/dev.c:4349 dev_queue_xmit include/linux/netdevice.h:3134 [inline] neigh_connected_output+0x569/0x660 net/core/neighbour.c:1592 neigh_output include/net/neighbour.h:542 [inline] ip6_finish_output2+0x23a9/0x2b30 net/ipv6/ip6_output.c:137 ip6_finish_output+0x855/0x12b0 net/ipv6/ip6_output.c:222 NF_HOOK_COND include/linux/netfilter.h:303 [inline] ip6_output+0x323/0x610 net/ipv6/ip6_output.c:243 dst_output include/net/dst.h:451 [inline] ip6_local_out+0xe9/0x140 net/ipv6/output_core.c:155 ip6_send_skb net/ipv6/ip6_output.c:1952 [inline] ip6_push_pending_frames+0x1f9/0x560 net/ipv6/ip6_output.c:1972 rawv6_push_pending_frames+0xbe8/0xdf0 net/ipv6/raw.c:582 rawv6_sendmsg+0x2b66/0x2e70 net/ipv6/raw.c:920 inet_sendmsg+0x105/0x190 net/ipv4/af_inet.c:847 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg net/socket.c:745 [inline] ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638 __sys_sendmsg net/socket.c:2667 [inline] __do_sys_sendmsg net/socket.c:2676 [inline] __se_sys_sendmsg net/socket.c:2674 [inline] __x64_sys_sendmsg+0x307/0x490 net/socket.c:2674 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b
CPU: 0 PID: 7345 Comm: syz-executor.3 Not tainted 6.7.0-rc8-syzkaller-00024-gac865f00af29 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
Fixes: fbfa743a9d2a ("ipv6: fix ip6_tnl_parse_tlv_enc_lim()") Reported-by: syzbot syzkaller@googlegroups.com Signed-off-by: Eric Dumazet edumazet@google.com Cc: Willem de Bruijn willemb@google.com Reviewed-by: Willem de Bruijn willemb@google.com Reviewed-by: David Ahern dsahern@kernel.org Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv6/ip6_tunnel.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-)
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c index afc922c88d17..9125e92d9917 100644 --- a/net/ipv6/ip6_tunnel.c +++ b/net/ipv6/ip6_tunnel.c @@ -399,7 +399,7 @@ __u16 ip6_tnl_parse_tlv_enc_lim(struct sk_buff *skb, __u8 *raw) const struct ipv6hdr *ipv6h = (const struct ipv6hdr *)raw; unsigned int nhoff = raw - skb->data; unsigned int off = nhoff + sizeof(*ipv6h); - u8 next, nexthdr = ipv6h->nexthdr; + u8 nexthdr = ipv6h->nexthdr;
while (ipv6_ext_hdr(nexthdr) && nexthdr != NEXTHDR_NONE) { struct ipv6_opt_hdr *hdr; @@ -410,25 +410,25 @@ __u16 ip6_tnl_parse_tlv_enc_lim(struct sk_buff *skb, __u8 *raw)
hdr = (struct ipv6_opt_hdr *)(skb->data + off); if (nexthdr == NEXTHDR_FRAGMENT) { - struct frag_hdr *frag_hdr = (struct frag_hdr *) hdr; - if (frag_hdr->frag_off) - break; optlen = 8; } else if (nexthdr == NEXTHDR_AUTH) { optlen = ipv6_authlen(hdr); } else { optlen = ipv6_optlen(hdr); } - /* cache hdr->nexthdr, since pskb_may_pull() might - * invalidate hdr - */ - next = hdr->nexthdr; - if (nexthdr == NEXTHDR_DEST) { - u16 i = 2;
- /* Remember : hdr is no longer valid at this point. */ - if (!pskb_may_pull(skb, off + optlen)) + if (!pskb_may_pull(skb, off + optlen)) + break; + + hdr = (struct ipv6_opt_hdr *)(skb->data + off); + if (nexthdr == NEXTHDR_FRAGMENT) { + struct frag_hdr *frag_hdr = (struct frag_hdr *)hdr; + + if (frag_hdr->frag_off) break; + } + if (nexthdr == NEXTHDR_DEST) { + u16 i = 2;
while (1) { struct ipv6_tlv_tnl_enc_lim *tel; @@ -449,7 +449,7 @@ __u16 ip6_tnl_parse_tlv_enc_lim(struct sk_buff *skb, __u8 *raw) i++; } } - nexthdr = next; + nexthdr = hdr->nexthdr; off += optlen; } return 0;