On receiving a packet the state index points to the rstate which must be
used to fill up IP and TCP headers. But if the state index points to a
rstate which is unitialized, i.e. filled with zeros, it gets stuck in an
infinite loop inside ip_fast_csum trying to compute the ip checsum of a
header with zero length.
89.666953: <2> [<ffffff9dd3e94d38>] slhc_uncompress+0x464/0x468
89.666965: <2> [<ffffff9dd3e87d88>] ppp_receive_nonmp_frame+0x3b4/0x65c
89.666978: <2> [<ffffff9dd3e89dd4>] ppp_receive_frame+0x64/0x7e0
89.666991: <2> [<ffffff9dd3e8a708>] ppp_input+0x104/0x198
89.667005: <2> [<ffffff9dd3e93868>] pppopns_recv_core+0x238/0x370
89.667027: <2> [<ffffff9dd4428fc8>] __sk_receive_skb+0xdc/0x250
89.667040: <2> [<ffffff9dd3e939e4>] pppopns_recv+0x44/0x60
89.667053: <2> [<ffffff9dd4426848>] __sock_queue_rcv_skb+0x16c/0x24c
89.667065: <2> [<ffffff9dd4426954>] sock_queue_rcv_skb+0x2c/0x38
89.667085: <2> [<ffffff9dd44f7358>] raw_rcv+0x124/0x154
89.667098: <2> [<ffffff9dd44f7568>] raw_local_deliver+0x1e0/0x22c
89.667117: <2> [<ffffff9dd44c8ba0>] ip_local_deliver_finish+0x70/0x24c
89.667131: <2> [<ffffff9dd44c92f4>] ip_local_deliver+0x100/0x10c
./scripts/faddr2line vmlinux slhc_uncompress+0x464/0x468 output:
ip_fast_csum at arch/arm64/include/asm/checksum.h:40
(inlined by) slhc_uncompress at drivers/net/slip/slhc.c:615
Adding a variable to indicate if the current rstate is initialized. If
such a packet arrives, move to toss state.
Signed-off-by: Tejaswi Tanikella <tejaswit@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
3f01ddb962