3.18-stable review patch. If anyone has any objections, please let me know.
------------------
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;