Re: [PATCH] slip: Check if rstate is initialized before uncompressing

[David Miller]

From: tejas...@codeaurora.org
Date: Tue, 10 Apr 2018 11:28:10 +0530

> On 2018-04-09 20:34, David Miller wrote:
>> From: Tejaswi Tanikella 
>> Date: Mon, 9 Apr 2018 14:23:49 +0530
>> 
>>> @@ -673,6 +677,7 @@ struct slcompress *
>>> 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 = 1;
>>> /* Put headers back on packet
>>  ...
>>>  struct cstate {
>>> byte_t  cs_this;/* connection id number (xmit) */
>>> +   byte_t  initialized;/* non-zero if initialized */
>> Please use 'bool' and true/false for 'initialized'.
> 
> Made the changes.

Please, when you are asked to fix a patch, post it as a new posting
with '[PATCH v2 net] slip: ...' in the subject line.

And also not as an attachment, all patches must be inline.

Thank you.

Re: [PATCH] slip: Check if rstate is initialized before uncompressing

[Guillaume Nault]

On Tue, Apr 10, 2018 at 11:28:10AM +0530, tejas...@codeaurora.org wrote:
> On 2018-04-09 20:34, David Miller wrote:
> > From: Tejaswi Tanikella 
> > Date: Mon, 9 Apr 2018 14:23:49 +0530
> > 
> > > @@ -673,6 +677,7 @@ struct slcompress *
> > >   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 = 1;
> > >   /* Put headers back on packet
> >  ...
> > >  struct cstate {
> > >   byte_t  cs_this;/* connection id number (xmit) */
> > > + byte_t  initialized;/* non-zero if initialized */
> > 
> > Please use 'bool' and true/false for 'initialized'.
> 
> Made the changes.

Hi Tejaswi,

Please send the new version of your patch as fresh new submission, with
proper subject prefix. In this case, it should be [PATCH net v2]. 'net'
because this is a bugfix and it should therefore target the 'net' tree.
'v2' because that's the second version of this series.

Also it'd be good if you could add a proper 'Fixes' tag in order to
help with stable backports. If the bug has always been there, just say
so.

I have no expertise on slhc, but overall, the patch content looks fine.

Guillaume

Re: [PATCH] slip: Check if rstate is initialized before uncompressing

[tejaswit]

On 2018-04-09 20:34, David Miller wrote:

From: Tejaswi Tanikella <tejas...@codeaurora.org>
Date: Mon, 9 Apr 2018 14:23:49 +0530


@@ -673,6 +677,7 @@ struct slcompress *
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 = 1;
/* Put headers back on packet

 ...

 struct cstate {
byte_t  cs_this;/* connection id number (xmit) */
+   byte_t  initialized;/* non-zero if initialized */


Please use 'bool' and true/false for 'initialized'.


Made the changes.
From b04441041034a5e044705d3c5a2cc338dd4bfc3a Mon Sep 17 00:00:00 2001
From: Tejaswi Tanikella <tejas...@codeaurora.org>
Date: Thu, 29 Mar 2018 14:46:41 +0530
Subject: [PATCH] slip: Check if rstate is initialized before uncompressing

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> [] slhc_uncompress+0x464/0x468
89.666965:   <2> [] ppp_receive_nonmp_frame+0x3b4/0x65c
89.666978:   <2> [] ppp_receive_frame+0x64/0x7e0
89.666991:   <2> [] ppp_input+0x104/0x198
89.667005:   <2> [] pppopns_recv_core+0x238/0x370
89.667027:   <2> [] __sk_receive_skb+0xdc/0x250
89.667040:   <2> [] pppopns_recv+0x44/0x60
89.667053:   <2> [] __sock_queue_rcv_skb+0x16c/0x24c
89.667065:   <2> [] sock_queue_rcv_skb+0x2c/0x38
89.667085:   <2> [] raw_rcv+0x124/0x154
89.667098:   <2> [] raw_local_deliver+0x1e0/0x22c
89.667117:   <2> [] ip_local_deliver_finish+0x70/0x24c
89.667131:   <2> [] 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 <tejas...@codeaurora.org>
---
 drivers/net/slip/slhc.c | 5 +
 include/net/slhc_vj.h   | 1 +
 2 files changed, 6 insertions(+)

diff --git a/drivers/net/slip/slhc.c b/drivers/net/slip/slhc.c
index 5782733..f4e93f5 100644
--- a/drivers/net/slip/slhc.c
+++ b/drivers/net/slip/slhc.c
@@ -509,6 +509,10 @@ struct slcompress *
 		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 @@ struct slcompress *
 	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
 	 */
diff --git a/include/net/slhc_vj.h b/include/net/slhc_vj.h
index 8716d59..8fcf890 100644
--- a/include/net/slhc_vj.h
+++ b/include/net/slhc_vj.h
@@ -127,6 +127,7 @@
  */
 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;
-- 
1.9.1

Re: [PATCH] slip: Check if rstate is initialized before uncompressing

[David Miller]

From: Tejaswi Tanikella 
Date: Mon, 9 Apr 2018 14:23:49 +0530

> @@ -673,6 +677,7 @@ struct slcompress *
>   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 = 1;
>   /* Put headers back on packet
 ...
>  struct cstate {
>   byte_t  cs_this;/* connection id number (xmit) */
> + byte_t  initialized;/* non-zero if initialized */

Please use 'bool' and true/false for 'initialized'.

[PATCH] slip: Check if rstate is initialized before uncompressing

[Tejaswi Tanikella]

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> [] slhc_uncompress+0x464/0x468
89.666965:   <2> [] ppp_receive_nonmp_frame+0x3b4/0x65c
89.666978:   <2> [] ppp_receive_frame+0x64/0x7e0
89.666991:   <2> [] ppp_input+0x104/0x198
89.667005:   <2> [] pppopns_recv_core+0x238/0x370
89.667027:   <2> [] __sk_receive_skb+0xdc/0x250
89.667040:   <2> [] pppopns_recv+0x44/0x60
89.667053:   <2> [] __sock_queue_rcv_skb+0x16c/0x24c
89.667065:   <2> [] sock_queue_rcv_skb+0x2c/0x38
89.667085:   <2> [] raw_rcv+0x124/0x154
89.667098:   <2> [] raw_local_deliver+0x1e0/0x22c
89.667117:   <2> [] ip_local_deliver_finish+0x70/0x24c
89.667131:   <2> [] 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 
---
 drivers/net/slip/slhc.c | 5 +
 include/net/slhc_vj.h   | 1 +
 2 files changed, 6 insertions(+)

diff --git a/drivers/net/slip/slhc.c b/drivers/net/slip/slhc.c
index 5782733..e710b0b 100644
--- a/drivers/net/slip/slhc.c
+++ b/drivers/net/slip/slhc.c
@@ -509,6 +509,10 @@ struct slcompress *
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 @@ struct slcompress *
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 = 1;
/* Put headers back on packet
 * Neither header checksum is recalculated
 */
diff --git a/include/net/slhc_vj.h b/include/net/slhc_vj.h
index 8716d59..d673365 100644
--- a/include/net/slhc_vj.h
+++ b/include/net/slhc_vj.h
@@ -127,6 +127,7 @@
  */
 struct cstate {
byte_t  cs_this;/* connection id number (xmit) */
+   byte_t  initialized;/* non-zero if initialized */
struct cstate *next;/* next in ring (xmit) */
struct iphdr cs_ip; /* ip/tcp hdr from most recent packet */
struct tcphdr cs_tcp;
-- 
1.9.1