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

[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> [<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>
---
 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

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

[David Miller]

From: Tejaswi Tanikella <tejaswit@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'.

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

[tejaswit]

[-- Attachment #1: Type: text/plain, Size: 627 bytes --]

On 2018-04-09 20:34, David Miller wrote:
> From: Tejaswi Tanikella <tejaswit@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.

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: 0001-slip-Check-if-rstate-is-initialized-before-uncompres.patch --]
[-- Type: text/x-diff; name=0001-slip-Check-if-rstate-is-initialized-before-uncompres.patch, Size: 3032 bytes --]

From b04441041034a5e044705d3c5a2cc338dd4bfc3a Mon Sep 17 00:00:00 2001
From: Tejaswi Tanikella <tejaswit@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> [<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>
---
 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

[Guillaume Nault]

On Tue, Apr 10, 2018 at 11:28:10AM +0530, tejaswit@codeaurora.org wrote:
> On 2018-04-09 20:34, David Miller wrote:
> > From: Tejaswi Tanikella <tejaswit@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.

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

[David Miller]

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

> On 2018-04-09 20:34, David Miller wrote:
>> From: Tejaswi Tanikella <tejaswit@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.

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 Wed, Apr 04, 2018 at 04:21:25PM +0530, Tejaswi Tanikella wrote:
> 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.
> 
Hi Tejaswi,

Patches aren't reviewed on linux-ppp but on netdev. You should post
your patch there.

Regards,

Guillaume

[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> [<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>
---
 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

[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, watch-dog bites.
It gets stuck in an infinite loop inside ip_fast_csum trying to compute
the ip checsum of a header with length zero.

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>
---
 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