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Groups > linux.kernel > #1548930 > unrolled thread

[PATCH] Update pptp handling to avoid null pointer deref.

Started byIan Kumlien <ian.kumlien@gmail.com>
First post2017-01-02 00:30 +0100
Last post2017-01-02 19:00 +0100
Articles 6 — 2 participants

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Contents

  [PATCH] Update pptp handling to avoid null pointer deref. Ian Kumlien <ian.kumlien@gmail.com> - 2017-01-02 00:30 +0100
    Re: [PATCH] Update pptp handling to avoid null pointer deref. David Miller <davem@davemloft.net> - 2017-01-02 05:10 +0100
      Re: [PATCH] Update pptp handling to avoid null pointer deref. Ian Kumlien <ian.kumlien@gmail.com> - 2017-01-02 09:10 +0100
    [PATCH] Update pptp handling to avoid null pointer deref. v2 Ian Kumlien <ian.kumlien@gmail.com> - 2017-01-02 09:20 +0100
    [PATCH] Update pptp handling to avoid null pointer deref. v2 Ian Kumlien <ian.kumlien@gmail.com> - 2017-01-02 09:20 +0100
      Re: [PATCH] Update pptp handling to avoid null pointer deref. v2 David Miller <davem@davemloft.net> - 2017-01-02 19:00 +0100

#1548930 — [PATCH] Update pptp handling to avoid null pointer deref.

FromIan Kumlien <ian.kumlien@gmail.com>
Date2017-01-02 00:30 +0100
Subject[PATCH] Update pptp handling to avoid null pointer deref.
Message-ID<sUXJD-6N6-13@gated-at.bofh.it>
__skb_flow_dissect can be called with a skb or a data packet, either
can be NULL. All calls seems to have been moved to __skb_header_pointer
except the pptp handling which is still calling skb_header_pointer.

skb_header_pointer will use skb->data and thus:
[  109.556866] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080
[  109.557102] IP: [<ffffffff88dc02f8>] __skb_flow_dissect+0xa88/0xce0
[  109.557263] PGD 0
[  109.557338]
[  109.557484] Oops: 0000 [#1] SMP
[  109.557562] Modules linked in: chaoskey
[  109.557783] CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.9.0 #79
[  109.557867] Hardware name: Supermicro A1SRM-LN7F/LN5F/A1SRM-LN7F-2758, BIOS 1.0c 11/04/2015
[  109.557957] task: ffff94085c27bc00 task.stack: ffffb745c0068000
[  109.558041] RIP: 0010:[<ffffffff88dc02f8>]  [<ffffffff88dc02f8>] __skb_flow_dissect+0xa88/0xce0
[  109.558203] RSP: 0018:ffff94087fc83d40  EFLAGS: 00010206
[  109.558286] RAX: 0000000000000130 RBX: ffffffff8975bf80 RCX: ffff94084fab6800
[  109.558373] RDX: 0000000000000010 RSI: 000000000000000c RDI: 0000000000000000
[  109.558460] RBP: 0000000000000b88 R08: 0000000000000000 R09: 0000000000000022
[  109.558547] R10: 0000000000000008 R11: ffff94087fc83e04 R12: 0000000000000000
[  109.558763] R13: ffff94084fab6800 R14: ffff94087fc83e04 R15: 000000000000002f
[  109.558979] FS:  0000000000000000(0000) GS:ffff94087fc80000(0000) knlGS:0000000000000000
[  109.559326] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  109.559539] CR2: 0000000000000080 CR3: 0000000281809000 CR4: 00000000001026e0
[  109.559753] Stack:
[  109.559957]  000000000000000c ffff94084fab6822 0000000000000001 ffff94085c2b5fc0
[  109.560578]  0000000000000001 0000000000002000 0000000000000000 0000000000000000
[  109.561200]  0000000000000000 0000000000000000 0000000000000000 0000000000000000
[  109.561820] Call Trace:
[  109.562027]  <IRQ>
[  109.562108]  [<ffffffff88dfb4fa>] ? eth_get_headlen+0x7a/0xf0
[  109.562522]  [<ffffffff88c5a35a>] ? igb_poll+0x96a/0xe80
[  109.562737]  [<ffffffff88dc912b>] ? net_rx_action+0x20b/0x350
[  109.562953]  [<ffffffff88546d68>] ? __do_softirq+0xe8/0x280
[  109.563169]  [<ffffffff8854704a>] ? irq_exit+0xaa/0xb0
[  109.563382]  [<ffffffff8847229b>] ? do_IRQ+0x4b/0xc0
[  109.563597]  [<ffffffff8902d4ff>] ? common_interrupt+0x7f/0x7f
[  109.563810]  <EOI>
[  109.563890]  [<ffffffff88d57530>] ? cpuidle_enter_state+0x130/0x2c0
[  109.564304]  [<ffffffff88d57520>] ? cpuidle_enter_state+0x120/0x2c0
[  109.564520]  [<ffffffff8857eacf>] ? cpu_startup_entry+0x19f/0x1f0
[  109.564737]  [<ffffffff8848d55a>] ? start_secondary+0x12a/0x140
[  109.564950] Code: 83 e2 20 a8 80 0f 84 60 01 00 00 c7 04 24 08 00
00 00 66 85 d2 0f 84 be fe ff ff e9 69 fe ff ff 8b 34 24 89 f2 83 c2
04 66 85 c0 <41> 8b 84 24 80 00 00 00 0f 49 d6 41 8d 31 01 d6 41 2b 84
24 84
[  109.569959] RIP  [<ffffffff88dc02f8>] __skb_flow_dissect+0xa88/0xce0
[  109.570245]  RSP <ffff94087fc83d40>
[  109.570453] CR2: 0000000000000080
---

Signed-off-by: Ian Kumlien <ian.kumlien@gmail.com>
---
 net/core/flow_dissector.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index c6d8207ffa7e..32e4e0158846 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -445,8 +445,9 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
 			if (hdr->flags & GRE_ACK)
 				offset += sizeof(((struct pptp_gre_header *)0)->ack);
 
-			ppp_hdr = skb_header_pointer(skb, nhoff + offset,
-						     sizeof(_ppp_hdr), _ppp_hdr);
+			ppp_hdr = __skb_header_pointer(skb, nhoff + offset,
+						     sizeof(_ppp_hdr),
+						     data, hlen, _ppp_hdr);
 			if (!ppp_hdr)
 				goto out_bad;
 
-- 
2.11.0

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#1548949

FromDavid Miller <davem@davemloft.net>
Date2017-01-02 05:10 +0100
Message-ID<sV26C-1en-7@gated-at.bofh.it>
In reply to#1548930
From: Ian Kumlien <ian.kumlien@gmail.com>
Date: Mon,  2 Jan 2017 00:19:36 +0100

> __skb_flow_dissect can be called with a skb or a data packet, either
> can be NULL. All calls seems to have been moved to __skb_header_pointer
> except the pptp handling which is still calling skb_header_pointer.
> 
> skb_header_pointer will use skb->data and thus:
 ...
> ---
> 
> Signed-off-by: Ian Kumlien <ian.kumlien@gmail.com>

You need to fix some parts of your submission.

Do not put the signoff after the "---", git will remove all text
after that "---" from the commit message.

You must include a proper "Fixes: " tag which indicates which change
introduced this regression.  This is critical for analyzing your fix
and also for figuring out which -stable releases your fix should be
backported to.

In this case the guilty commit is ab10dccb1160 ("rps: Inspect PPTP
encapsulated by GRE to get flow hash")

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#1549012

FromIan Kumlien <ian.kumlien@gmail.com>
Date2017-01-02 09:10 +0100
Message-ID<sV5QR-3Zw-5@gated-at.bofh.it>
In reply to#1548949
On Mon, Jan 2, 2017 at 5:07 AM, David Miller <davem@davemloft.net> wrote:
> From: Ian Kumlien <ian.kumlien@gmail.com>
> Date: Mon,  2 Jan 2017 00:19:36 +0100
>
>> __skb_flow_dissect can be called with a skb or a data packet, either
>> can be NULL. All calls seems to have been moved to __skb_header_pointer
>> except the pptp handling which is still calling skb_header_pointer.
>>
>> skb_header_pointer will use skb->data and thus:
>  ...
>> ---
>>
>> Signed-off-by: Ian Kumlien <ian.kumlien@gmail.com>
>
> You need to fix some parts of your submission.
>
> Do not put the signoff after the "---", git will remove all text
> after that "---" from the commit message.

Sorry, I tend to do that automatically

> You must include a proper "Fixes: " tag which indicates which change
> introduced this regression.  This is critical for analyzing your fix
> and also for figuring out which -stable releases your fix should be
> backported to.

I it's supposed to be added after 4.7 but i can't find it in 4.8, will
send it as a stable patch for 4.9

> In this case the guilty commit is ab10dccb1160 ("rps: Inspect PPTP
> encapsulated by GRE to get flow hash")

Thanks, =)

Now patch is incomming

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#1549015 — [PATCH] Update pptp handling to avoid null pointer deref. v2

FromIan Kumlien <ian.kumlien@gmail.com>
Date2017-01-02 09:20 +0100
Subject[PATCH] Update pptp handling to avoid null pointer deref. v2
Message-ID<sV60y-45j-3@gated-at.bofh.it>
In reply to#1548930
__skb_flow_dissect can be called with a skb or a data packet, either
can be NULL. All calls seems to have been moved to __skb_header_pointer
except the pptp handling which is still calling skb_header_pointer.

skb_header_pointer will use skb->data and thus:
[  109.556866] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080
[  109.557102] IP: [<ffffffff88dc02f8>] __skb_flow_dissect+0xa88/0xce0
[  109.557263] PGD 0
[  109.557338]
[  109.557484] Oops: 0000 [#1] SMP
[  109.557562] Modules linked in: chaoskey
[  109.557783] CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.9.0 #79
[  109.557867] Hardware name: Supermicro A1SRM-LN7F/LN5F/A1SRM-LN7F-2758, BIOS 1.0c 11/04/2015
[  109.557957] task: ffff94085c27bc00 task.stack: ffffb745c0068000
[  109.558041] RIP: 0010:[<ffffffff88dc02f8>]  [<ffffffff88dc02f8>] __skb_flow_dissect+0xa88/0xce0
[  109.558203] RSP: 0018:ffff94087fc83d40  EFLAGS: 00010206
[  109.558286] RAX: 0000000000000130 RBX: ffffffff8975bf80 RCX: ffff94084fab6800
[  109.558373] RDX: 0000000000000010 RSI: 000000000000000c RDI: 0000000000000000
[  109.558460] RBP: 0000000000000b88 R08: 0000000000000000 R09: 0000000000000022
[  109.558547] R10: 0000000000000008 R11: ffff94087fc83e04 R12: 0000000000000000
[  109.558763] R13: ffff94084fab6800 R14: ffff94087fc83e04 R15: 000000000000002f
[  109.558979] FS:  0000000000000000(0000) GS:ffff94087fc80000(0000) knlGS:0000000000000000
[  109.559326] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  109.559539] CR2: 0000000000000080 CR3: 0000000281809000 CR4: 00000000001026e0
[  109.559753] Stack:
[  109.559957]  000000000000000c ffff94084fab6822 0000000000000001 ffff94085c2b5fc0
[  109.560578]  0000000000000001 0000000000002000 0000000000000000 0000000000000000
[  109.561200]  0000000000000000 0000000000000000 0000000000000000 0000000000000000
[  109.561820] Call Trace:
[  109.562027]  <IRQ>
[  109.562108]  [<ffffffff88dfb4fa>] ? eth_get_headlen+0x7a/0xf0
[  109.562522]  [<ffffffff88c5a35a>] ? igb_poll+0x96a/0xe80
[  109.562737]  [<ffffffff88dc912b>] ? net_rx_action+0x20b/0x350
[  109.562953]  [<ffffffff88546d68>] ? __do_softirq+0xe8/0x280
[  109.563169]  [<ffffffff8854704a>] ? irq_exit+0xaa/0xb0
[  109.563382]  [<ffffffff8847229b>] ? do_IRQ+0x4b/0xc0
[  109.563597]  [<ffffffff8902d4ff>] ? common_interrupt+0x7f/0x7f
[  109.563810]  <EOI>
[  109.563890]  [<ffffffff88d57530>] ? cpuidle_enter_state+0x130/0x2c0
[  109.564304]  [<ffffffff88d57520>] ? cpuidle_enter_state+0x120/0x2c0
[  109.564520]  [<ffffffff8857eacf>] ? cpu_startup_entry+0x19f/0x1f0
[  109.564737]  [<ffffffff8848d55a>] ? start_secondary+0x12a/0x140
[  109.564950] Code: 83 e2 20 a8 80 0f 84 60 01 00 00 c7 04 24 08 00
00 00 66 85 d2 0f 84 be fe ff ff e9 69 fe ff ff 8b 34 24 89 f2 83 c2
04 66 85 c0 <41> 8b 84 24 80 00 00 00 0f 49 d6 41 8d 31 01 d6 41 2b 84
24 84
[  109.569959] RIP  [<ffffffff88dc02f8>] __skb_flow_dissect+0xa88/0xce0
[  109.570245]  RSP <ffff94087fc83d40>
[  109.570453] CR2: 0000000000000080

Fixes: ab10dccb1160 ("rps: Inspect PPTP encapsulated by GRE to get flow hash")
Signed-off-by: Ian Kumlien <ian.kumlien@gmail.com>
---
 net/core/flow_dissector.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index c6d8207ffa7e..32e4e0158846 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -445,8 +445,9 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
 			if (hdr->flags & GRE_ACK)
 				offset += sizeof(((struct pptp_gre_header *)0)->ack);
 
-			ppp_hdr = skb_header_pointer(skb, nhoff + offset,
-						     sizeof(_ppp_hdr), _ppp_hdr);
+			ppp_hdr = __skb_header_pointer(skb, nhoff + offset,
+						     sizeof(_ppp_hdr),
+						     data, hlen, _ppp_hdr);
 			if (!ppp_hdr)
 				goto out_bad;
 
-- 
2.11.0

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#1549016 — [PATCH] Update pptp handling to avoid null pointer deref. v2

FromIan Kumlien <ian.kumlien@gmail.com>
Date2017-01-02 09:20 +0100
Subject[PATCH] Update pptp handling to avoid null pointer deref. v2
Message-ID<sV60y-45j-9@gated-at.bofh.it>
In reply to#1548930
__skb_flow_dissect can be called with a skb or a data packet, either
can be NULL. All calls seems to have been moved to __skb_header_pointer
except the pptp handling which is still calling skb_header_pointer.

skb_header_pointer will use skb->data and thus:
[  109.556866] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080
[  109.557102] IP: [<ffffffff88dc02f8>] __skb_flow_dissect+0xa88/0xce0
[  109.557263] PGD 0
[  109.557338]
[  109.557484] Oops: 0000 [#1] SMP
[  109.557562] Modules linked in: chaoskey
[  109.557783] CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.9.0 #79
[  109.557867] Hardware name: Supermicro A1SRM-LN7F/LN5F/A1SRM-LN7F-2758, BIOS 1.0c 11/04/2015
[  109.557957] task: ffff94085c27bc00 task.stack: ffffb745c0068000
[  109.558041] RIP: 0010:[<ffffffff88dc02f8>]  [<ffffffff88dc02f8>] __skb_flow_dissect+0xa88/0xce0
[  109.558203] RSP: 0018:ffff94087fc83d40  EFLAGS: 00010206
[  109.558286] RAX: 0000000000000130 RBX: ffffffff8975bf80 RCX: ffff94084fab6800
[  109.558373] RDX: 0000000000000010 RSI: 000000000000000c RDI: 0000000000000000
[  109.558460] RBP: 0000000000000b88 R08: 0000000000000000 R09: 0000000000000022
[  109.558547] R10: 0000000000000008 R11: ffff94087fc83e04 R12: 0000000000000000
[  109.558763] R13: ffff94084fab6800 R14: ffff94087fc83e04 R15: 000000000000002f
[  109.558979] FS:  0000000000000000(0000) GS:ffff94087fc80000(0000) knlGS:0000000000000000
[  109.559326] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  109.559539] CR2: 0000000000000080 CR3: 0000000281809000 CR4: 00000000001026e0
[  109.559753] Stack:
[  109.559957]  000000000000000c ffff94084fab6822 0000000000000001 ffff94085c2b5fc0
[  109.560578]  0000000000000001 0000000000002000 0000000000000000 0000000000000000
[  109.561200]  0000000000000000 0000000000000000 0000000000000000 0000000000000000
[  109.561820] Call Trace:
[  109.562027]  <IRQ>
[  109.562108]  [<ffffffff88dfb4fa>] ? eth_get_headlen+0x7a/0xf0
[  109.562522]  [<ffffffff88c5a35a>] ? igb_poll+0x96a/0xe80
[  109.562737]  [<ffffffff88dc912b>] ? net_rx_action+0x20b/0x350
[  109.562953]  [<ffffffff88546d68>] ? __do_softirq+0xe8/0x280
[  109.563169]  [<ffffffff8854704a>] ? irq_exit+0xaa/0xb0
[  109.563382]  [<ffffffff8847229b>] ? do_IRQ+0x4b/0xc0
[  109.563597]  [<ffffffff8902d4ff>] ? common_interrupt+0x7f/0x7f
[  109.563810]  <EOI>
[  109.563890]  [<ffffffff88d57530>] ? cpuidle_enter_state+0x130/0x2c0
[  109.564304]  [<ffffffff88d57520>] ? cpuidle_enter_state+0x120/0x2c0
[  109.564520]  [<ffffffff8857eacf>] ? cpu_startup_entry+0x19f/0x1f0
[  109.564737]  [<ffffffff8848d55a>] ? start_secondary+0x12a/0x140
[  109.564950] Code: 83 e2 20 a8 80 0f 84 60 01 00 00 c7 04 24 08 00
00 00 66 85 d2 0f 84 be fe ff ff e9 69 fe ff ff 8b 34 24 89 f2 83 c2
04 66 85 c0 <41> 8b 84 24 80 00 00 00 0f 49 d6 41 8d 31 01 d6 41 2b 84
24 84
[  109.569959] RIP  [<ffffffff88dc02f8>] __skb_flow_dissect+0xa88/0xce0
[  109.570245]  RSP <ffff94087fc83d40>
[  109.570453] CR2: 0000000000000080

Fixes: ab10dccb1160 ("rps: Inspect PPTP encapsulated by GRE to get flow hash")
Signed-off-by: Ian Kumlien <ian.kumlien@gmail.com>
---
 net/core/flow_dissector.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index c6d8207ffa7e..32e4e0158846 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -445,8 +445,9 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
 			if (hdr->flags & GRE_ACK)
 				offset += sizeof(((struct pptp_gre_header *)0)->ack);
 
-			ppp_hdr = skb_header_pointer(skb, nhoff + offset,
-						     sizeof(_ppp_hdr), _ppp_hdr);
+			ppp_hdr = __skb_header_pointer(skb, nhoff + offset,
+						     sizeof(_ppp_hdr),
+						     data, hlen, _ppp_hdr);
 			if (!ppp_hdr)
 				goto out_bad;
 
-- 
2.11.0

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#1549332 — Re: [PATCH] Update pptp handling to avoid null pointer deref. v2

FromDavid Miller <davem@davemloft.net>
Date2017-01-02 19:00 +0100
SubjectRe: [PATCH] Update pptp handling to avoid null pointer deref. v2
Message-ID<sVf3Q-1Xy-23@gated-at.bofh.it>
In reply to#1549016
From: Ian Kumlien <ian.kumlien@gmail.com>
Date: Mon,  2 Jan 2017 09:18:35 +0100

> __skb_flow_dissect can be called with a skb or a data packet, either
> can be NULL. All calls seems to have been moved to __skb_header_pointer
> except the pptp handling which is still calling skb_header_pointer.
 ...
> Fixes: ab10dccb1160 ("rps: Inspect PPTP encapsulated by GRE to get flow hash")
> Signed-off-by: Ian Kumlien <ian.kumlien@gmail.com>

Applied and queued up for -stable.

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