On Thu, Sep 23, 2021 at 12:05:04AM -0400, Xin Long wrote:
> We should always check if skb_header_pointer's return is NULL before
> using it, otherwise it may cause null-ptr-deref, as syzbot reported:
>
> KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
> RIP: 0010:sctp_rcv_ootb net/sctp/input.c:705 [inline]
> RIP: 0010:sctp_rcv+0x1d84/0x3220 net/sctp/input.c:196
> Call Trace:
> <IRQ>
> sctp6_rcv+0x38/0x60 net/sctp/ipv6.c:1109
> ip6_protocol_deliver_rcu+0x2e9/0x1ca0 net/ipv6/ip6_input.c:422
> ip6_input_finish+0x62/0x170 net/ipv6/ip6_input.c:463
> NF_HOOK include/linux/netfilter.h:307 [inline]
> NF_HOOK include/linux/netfilter.h:301 [inline]
> ip6_input+0x9c/0xd0 net/ipv6/ip6_input.c:472
> dst_input include/net/dst.h:460 [inline]
> ip6_rcv_finish net/ipv6/ip6_input.c:76 [inline]
> NF_HOOK include/linux/netfilter.h:307 [inline]
> NF_HOOK include/linux/netfilter.h:301 [inline]
> ipv6_rcv+0x28c/0x3c0 net/ipv6/ip6_input.c:297
>
> Fixes: 3acb50c18d8d ("sctp: delay as much as possible skb_linearize")
> Reported-by: syzbot+581aff2ae6b860625116@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx>
