| Message ID | 20240328110955.1026716-1-edumazet@google.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] erspan: make sure erspan_base_hdr is present in skb->head | expand |
On Thu, Mar 28, 2024 at 12:09 PM Eric Dumazet <edumazet@google.com> wrote: > > syzbot reported a problem in ip6erspan_rcv() [1] > > Issue is that ip6erspan_rcv() (and erspan_rcv()) no longer make > sure erspan_base_hdr is present in skb linear part (skb->head) > before getting @ver field from it. > > Add the missing pskb_may_pull() calls. > > [1] > > > CPU: 1 PID: 5045 Comm: syz-executor114 Not tainted 6.9.0-rc1-syzkaller-00021-g962490525cff #0 > > Fixes: cb73ee40b1b3 ("net: ip_gre: use erspan key field for tunnel lookup") > Reported-by: syzbot+1c1cf138518bf0c53d68@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/netdev/000000000000772f2c0614b66ef7@google.com/ > Signed-off-by: Eric Dumazet <edumazet@google.com> > Cc: Lorenzo Bianconi <lorenzo@kernel.org> > --- > net/ipv4/ip_gre.c | 4 ++++ > net/ipv6/ip6_gre.c | 3 +++ > 2 files changed, 7 insertions(+) > > diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c > index 7b16c211b904473cc5e350aafdefb86fbf1b3693..56982d6fb0cd6c39a0e769e130fd47460873b0d4 100644 > --- a/net/ipv4/ip_gre.c > +++ b/net/ipv4/ip_gre.c > @@ -280,6 +280,10 @@ static int erspan_rcv(struct sk_buff *skb, struct tnl_ptk_info *tpi, > tpi->flags | TUNNEL_NO_KEY, > iph->saddr, iph->daddr, 0); > } else { > + if (unlikely(!pskb_may_pull(skb, > + gre_hdr_len + sizeof(*ershdr)))) > + return PACKET_REJECT; Sorry, I have to reload iph at this point, I will send a v2. > + > ershdr = (struct erspan_base_hdr *)(skb->data + gre_hdr_len); > ver = ershdr->ver; > tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex, > diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c > index ca7e77e842835a6d153891fdca7dc8f196e0a2ba..c89aef524df9a2039d223fd2dd7566a9e1f7d3f4 100644 > --- a/net/ipv6/ip6_gre.c > +++ b/net/ipv6/ip6_gre.c > @@ -528,6 +528,9 @@ static int ip6erspan_rcv(struct sk_buff *skb, > struct ip6_tnl *tunnel; > u8 ver; > > + if (unlikely(!pskb_may_pull(skb, sizeof(*ershdr)))) > + return PACKET_REJECT; > + > ipv6h = ipv6_hdr(skb); > ershdr = (struct erspan_base_hdr *)skb->data; > ver = ershdr->ver; > -- > 2.44.0.396.g6e790dbe36-goog >
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index 7b16c211b904473cc5e350aafdefb86fbf1b3693..56982d6fb0cd6c39a0e769e130fd47460873b0d4 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -280,6 +280,10 @@ static int erspan_rcv(struct sk_buff *skb, struct tnl_ptk_info *tpi, tpi->flags | TUNNEL_NO_KEY, iph->saddr, iph->daddr, 0); } else { + if (unlikely(!pskb_may_pull(skb, + gre_hdr_len + sizeof(*ershdr)))) + return PACKET_REJECT; + ershdr = (struct erspan_base_hdr *)(skb->data + gre_hdr_len); ver = ershdr->ver; tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex, diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c index ca7e77e842835a6d153891fdca7dc8f196e0a2ba..c89aef524df9a2039d223fd2dd7566a9e1f7d3f4 100644 --- a/net/ipv6/ip6_gre.c +++ b/net/ipv6/ip6_gre.c @@ -528,6 +528,9 @@ static int ip6erspan_rcv(struct sk_buff *skb, struct ip6_tnl *tunnel; u8 ver; + if (unlikely(!pskb_may_pull(skb, sizeof(*ershdr)))) + return PACKET_REJECT; + ipv6h = ipv6_hdr(skb); ershdr = (struct erspan_base_hdr *)skb->data; ver = ershdr->ver;
syzbot reported a problem in ip6erspan_rcv() [1] Issue is that ip6erspan_rcv() (and erspan_rcv()) no longer make sure erspan_base_hdr is present in skb linear part (skb->head) before getting @ver field from it. Add the missing pskb_may_pull() calls. [1] BUG: KMSAN: uninit-value in pskb_may_pull_reason include/linux/skbuff.h:2742 [inline] BUG: KMSAN: uninit-value in pskb_may_pull include/linux/skbuff.h:2756 [inline] BUG: KMSAN: uninit-value in ip6erspan_rcv net/ipv6/ip6_gre.c:541 [inline] BUG: KMSAN: uninit-value in gre_rcv+0x11f8/0x1930 net/ipv6/ip6_gre.c:610 pskb_may_pull_reason include/linux/skbuff.h:2742 [inline] pskb_may_pull include/linux/skbuff.h:2756 [inline] ip6erspan_rcv net/ipv6/ip6_gre.c:541 [inline] gre_rcv+0x11f8/0x1930 net/ipv6/ip6_gre.c:610 ip6_protocol_deliver_rcu+0x1d4c/0x2ca0 net/ipv6/ip6_input.c:438 ip6_input_finish net/ipv6/ip6_input.c:483 [inline] NF_HOOK include/linux/netfilter.h:314 [inline] ip6_input+0x15d/0x430 net/ipv6/ip6_input.c:492 ip6_mc_input+0xa7e/0xc80 net/ipv6/ip6_input.c:586 dst_input include/net/dst.h:460 [inline] ip6_rcv_finish+0x955/0x970 net/ipv6/ip6_input.c:79 NF_HOOK include/linux/netfilter.h:314 [inline] ipv6_rcv+0xde/0x390 net/ipv6/ip6_input.c:310 __netif_receive_skb_one_core net/core/dev.c:5538 [inline] __netif_receive_skb+0x1da/0xa00 net/core/dev.c:5652 netif_receive_skb_internal net/core/dev.c:5738 [inline] netif_receive_skb+0x58/0x660 net/core/dev.c:5798 tun_rx_batched+0x3ee/0x980 drivers/net/tun.c:1549 tun_get_user+0x5566/0x69e0 drivers/net/tun.c:2002 tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048 call_write_iter include/linux/fs.h:2108 [inline] new_sync_write fs/read_write.c:497 [inline] vfs_write+0xb63/0x1520 fs/read_write.c:590 ksys_write+0x20f/0x4c0 fs/read_write.c:643 __do_sys_write fs/read_write.c:655 [inline] __se_sys_write fs/read_write.c:652 [inline] __x64_sys_write+0x93/0xe0 fs/read_write.c:652 do_syscall_64+0xd5/0x1f0 entry_SYSCALL_64_after_hwframe+0x6d/0x75 Uninit was created at: slab_post_alloc_hook mm/slub.c:3804 [inline] slab_alloc_node mm/slub.c:3845 [inline] kmem_cache_alloc_node+0x613/0xc50 mm/slub.c:3888 kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:577 __alloc_skb+0x35b/0x7a0 net/core/skbuff.c:668 alloc_skb include/linux/skbuff.h:1318 [inline] alloc_skb_with_frags+0xc8/0xbf0 net/core/skbuff.c:6504 sock_alloc_send_pskb+0xa81/0xbf0 net/core/sock.c:2795 tun_alloc_skb drivers/net/tun.c:1525 [inline] tun_get_user+0x209a/0x69e0 drivers/net/tun.c:1846 tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048 call_write_iter include/linux/fs.h:2108 [inline] new_sync_write fs/read_write.c:497 [inline] vfs_write+0xb63/0x1520 fs/read_write.c:590 ksys_write+0x20f/0x4c0 fs/read_write.c:643 __do_sys_write fs/read_write.c:655 [inline] __se_sys_write fs/read_write.c:652 [inline] __x64_sys_write+0x93/0xe0 fs/read_write.c:652 do_syscall_64+0xd5/0x1f0 entry_SYSCALL_64_after_hwframe+0x6d/0x75 CPU: 1 PID: 5045 Comm: syz-executor114 Not tainted 6.9.0-rc1-syzkaller-00021-g962490525cff #0 Fixes: cb73ee40b1b3 ("net: ip_gre: use erspan key field for tunnel lookup") Reported-by: syzbot+1c1cf138518bf0c53d68@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/000000000000772f2c0614b66ef7@google.com/ Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Lorenzo Bianconi <lorenzo@kernel.org> --- net/ipv4/ip_gre.c | 4 ++++ net/ipv6/ip6_gre.c | 3 +++ 2 files changed, 7 insertions(+)