| From foo@baz Tue Apr 17 17:00:10 CEST 2018 |
| From: Tejaswi Tanikella <tejaswit@codeaurora.org> |
| Date: Wed, 11 Apr 2018 16:34:47 +0530 |
| Subject: slip: Check if rstate is initialized before uncompressing |
| |
| From: Tejaswi Tanikella <tejaswit@codeaurora.org> |
| |
| |
| [ Upstream commit 3f01ddb962dc506916c243f9524e8bef97119b77 ] |
| |
| 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> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| drivers/net/slip/slhc.c | 5 +++++ |
| include/net/slhc_vj.h | 1 + |
| 2 files changed, 6 insertions(+) |
| |
| --- a/drivers/net/slip/slhc.c |
| +++ b/drivers/net/slip/slhc.c |
| @@ -509,6 +509,10 @@ slhc_uncompress(struct slcompress *comp, |
| if(x < 0 || x > comp->rslot_limit) |
| goto bad; |
| |
| + /* Check if the cstate is initialized */ |
| + if (!comp->rstate[x].initialized) |
| + goto bad; |
| + |
| comp->flags &=~ SLF_TOSS; |
| comp->recv_current = x; |
| } else { |
| @@ -673,6 +677,7 @@ slhc_remember(struct slcompress *comp, u |
| if (cs->cs_tcp.doff > 5) |
| memcpy(cs->cs_tcpopt, icp + ihl*4 + sizeof(struct tcphdr), (cs->cs_tcp.doff - 5) * 4); |
| cs->cs_hsize = ihl*2 + cs->cs_tcp.doff*2; |
| + cs->initialized = true; |
| /* Put headers back on packet |
| * Neither header checksum is recalculated |
| */ |
| --- a/include/net/slhc_vj.h |
| +++ b/include/net/slhc_vj.h |
| @@ -127,6 +127,7 @@ typedef __u32 int32; |
| */ |
| struct cstate { |
| byte_t cs_this; /* connection id number (xmit) */ |
| + bool initialized; /* true if initialized */ |
| struct cstate *next; /* next in ring (xmit) */ |
| struct iphdr cs_ip; /* ip/tcp hdr from most recent packet */ |
| struct tcphdr cs_tcp; |