* [PATCH net] net/dccp: fix use-after-free in dccp_invalid_packet
@ 2016-11-28 14:26 Eric Dumazet
2016-11-28 14:40 ` Arnaldo Carvalho de Melo
` (5 more replies)
0 siblings, 6 replies; 7+ messages in thread
From: Eric Dumazet @ 2016-11-28 14:26 UTC (permalink / raw)
To: dccp
From: Eric Dumazet <edumazet@google.com>
pskb_may_pull() can reallocate skb->head, we need to reload dh pointer
in dccp_invalid_packet() or risk use after free.
Bug found by Andrey Konovalov using syzkaller.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
---
net/dccp/ipv4.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index b567c8725aea..edbe59d203ef 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -700,6 +700,7 @@ int dccp_invalid_packet(struct sk_buff *skb)
{
const struct dccp_hdr *dh;
unsigned int cscov;
+ u8 dccph_doff;
if (skb->pkt_type != PACKET_HOST)
return 1;
@@ -721,18 +722,19 @@ int dccp_invalid_packet(struct sk_buff *skb)
/*
* If P.Data Offset is too small for packet type, drop packet and return
*/
- if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
- DCCP_WARN("P.Data Offset(%u) too small\n", dh->dccph_doff);
+ dccph_doff = dh->dccph_doff;
+ if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
+ DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff);
return 1;
}
/*
* If P.Data Offset is too too large for packet, drop packet and return
*/
- if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
- DCCP_WARN("P.Data Offset(%u) too large\n", dh->dccph_doff);
+ if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) {
+ DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff);
return 1;
}
-
+ dh = dccp_hdr(skb);
/*
* If P.type is not Data, Ack, or DataAck and P.X = 0 (the packet
* has short sequence numbers), drop packet and return
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH net] net/dccp: fix use-after-free in dccp_invalid_packet
2016-11-28 14:26 [PATCH net] net/dccp: fix use-after-free in dccp_invalid_packet Eric Dumazet
@ 2016-11-28 14:40 ` Arnaldo Carvalho de Melo
2016-11-28 14:47 ` Eric Dumazet
` (4 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: Arnaldo Carvalho de Melo @ 2016-11-28 14:40 UTC (permalink / raw)
To: dccp
Em Mon, Nov 28, 2016 at 06:26:49AM -0800, Eric Dumazet escreveu:
> From: Eric Dumazet <edumazet@google.com>
>
> pskb_may_pull() can reallocate skb->head, we need to reload dh pointer
> in dccp_invalid_packet() or risk use after free.
>
> Bug found by Andrey Konovalov using syzkaller.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
I was about to send exactly this patch, and while looking at it I think
the patch below needs to go in as well, no? To follow the advice of that
Warning line there :-)
From: Arnaldo Carvalho de Melo <acme@redhat.com>
pskb_may_pull() can reallocate skb->head, so we can't access
iph->frag_off or risk use after free, save it to a variable and us that
later.
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 5ddf5cda07f4..9462070561a3 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1198,6 +1198,7 @@ struct sk_buff *inet_gso_segment(struct sk_buff *skb,
struct iphdr *iph;
int proto, tot_len;
int nhoff;
+ u16 frag_off;
int ihl;
int id;
@@ -1213,6 +1214,7 @@ struct sk_buff *inet_gso_segment(struct sk_buff *skb,
id = ntohs(iph->id);
proto = iph->protocol;
+ frag_off = iph->frag_off;
/* Warning: after this point, iph might be no longer valid */
if (unlikely(!pskb_may_pull(skb, ihl)))
@@ -1233,7 +1235,7 @@ struct sk_buff *inet_gso_segment(struct sk_buff *skb,
fixedid = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TCP_FIXEDID);
/* fixed ID is invalid if DF bit is not set */
- if (fixedid && !(iph->frag_off & htons(IP_DF)))
+ if (fixedid && !(frag_off & htons(IP_DF)))
goto out;
}
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH net] net/dccp: fix use-after-free in dccp_invalid_packet
2016-11-28 14:26 [PATCH net] net/dccp: fix use-after-free in dccp_invalid_packet Eric Dumazet
2016-11-28 14:40 ` Arnaldo Carvalho de Melo
@ 2016-11-28 14:47 ` Eric Dumazet
2016-11-28 15:05 ` Arnaldo Carvalho de Melo
` (3 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: Eric Dumazet @ 2016-11-28 14:47 UTC (permalink / raw)
To: dccp
On Mon, 2016-11-28 at 11:40 -0300, Arnaldo Carvalho de Melo wrote:
> Em Mon, Nov 28, 2016 at 06:26:49AM -0800, Eric Dumazet escreveu:
> > From: Eric Dumazet <edumazet@google.com>
> >
> > pskb_may_pull() can reallocate skb->head, we need to reload dh pointer
> > in dccp_invalid_packet() or risk use after free.
> >
> > Bug found by Andrey Konovalov using syzkaller.
> >
> > Signed-off-by: Eric Dumazet <edumazet@google.com>
> > Reported-by: Andrey Konovalov <andreyknvl@google.com>
>
> Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
>
> I was about to send exactly this patch, and while looking at it I think
> the patch below needs to go in as well, no? To follow the advice of that
> Warning line there :-)
>
> From: Arnaldo Carvalho de Melo <acme@redhat.com>
>
> pskb_may_pull() can reallocate skb->head, so we can't access
> iph->frag_off or risk use after free, save it to a variable and us that
> later.
>
> Cc: Andrey Konovalov <andreyknvl@google.com>
> Cc: Eric Dumazet <edumazet@google.com>
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
>
> diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
> index 5ddf5cda07f4..9462070561a3 100644
> --- a/net/ipv4/af_inet.c
> +++ b/net/ipv4/af_inet.c
> @@ -1198,6 +1198,7 @@ struct sk_buff *inet_gso_segment(struct sk_buff *skb,
> struct iphdr *iph;
> int proto, tot_len;
> int nhoff;
> + u16 frag_off;
> int ihl;
> int id;
>
> @@ -1213,6 +1214,7 @@ struct sk_buff *inet_gso_segment(struct sk_buff *skb,
>
> id = ntohs(iph->id);
> proto = iph->protocol;
> + frag_off = iph->frag_off;
>
> /* Warning: after this point, iph might be no longer valid */
> if (unlikely(!pskb_may_pull(skb, ihl)))
> @@ -1233,7 +1235,7 @@ struct sk_buff *inet_gso_segment(struct sk_buff *skb,
> fixedid = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TCP_FIXEDID);
>
> /* fixed ID is invalid if DF bit is not set */
> - if (fixedid && !(iph->frag_off & htons(IP_DF)))
> + if (fixedid && !(frag_off & htons(IP_DF)))
> goto out;
> }
>
I do not see why this patch would be needed ?
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH net] net/dccp: fix use-after-free in dccp_invalid_packet
2016-11-28 14:26 [PATCH net] net/dccp: fix use-after-free in dccp_invalid_packet Eric Dumazet
2016-11-28 14:40 ` Arnaldo Carvalho de Melo
2016-11-28 14:47 ` Eric Dumazet
@ 2016-11-28 15:05 ` Arnaldo Carvalho de Melo
2016-11-28 15:20 ` Eric Dumazet
` (2 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: Arnaldo Carvalho de Melo @ 2016-11-28 15:05 UTC (permalink / raw)
To: dccp
Em Mon, Nov 28, 2016 at 06:47:14AM -0800, Eric Dumazet escreveu:
> On Mon, 2016-11-28 at 11:40 -0300, Arnaldo Carvalho de Melo wrote:
> > Em Mon, Nov 28, 2016 at 06:26:49AM -0800, Eric Dumazet escreveu:
> > > From: Eric Dumazet <edumazet@google.com>
> > >
> > > pskb_may_pull() can reallocate skb->head, we need to reload dh pointer
> > > in dccp_invalid_packet() or risk use after free.
> > >
> > > Bug found by Andrey Konovalov using syzkaller.
> > >
> > > Signed-off-by: Eric Dumazet <edumazet@google.com>
> > > Reported-by: Andrey Konovalov <andreyknvl@google.com>
> >
> > Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> >
> > I was about to send exactly this patch, and while looking at it I think
> > the patch below needs to go in as well, no? To follow the advice of that
> > Warning line there :-)
> >
> > From: Arnaldo Carvalho de Melo <acme@redhat.com>
> >
> > pskb_may_pull() can reallocate skb->head, so we can't access
> > iph->frag_off or risk use after free, save it to a variable and us that
> > later.
> >
> > Cc: Andrey Konovalov <andreyknvl@google.com>
> > Cc: Eric Dumazet <edumazet@google.com>
> > Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> >
> > diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
> > index 5ddf5cda07f4..9462070561a3 100644
> > --- a/net/ipv4/af_inet.c
> > +++ b/net/ipv4/af_inet.c
> > @@ -1198,6 +1198,7 @@ struct sk_buff *inet_gso_segment(struct sk_buff *skb,
> > struct iphdr *iph;
> > int proto, tot_len;
> > int nhoff;
> > + u16 frag_off;
> > int ihl;
> > int id;
> >
> > @@ -1213,6 +1214,7 @@ struct sk_buff *inet_gso_segment(struct sk_buff *skb,
> >
> > id = ntohs(iph->id);
> > proto = iph->protocol;
> > + frag_off = iph->frag_off;
> >
> > /* Warning: after this point, iph might be no longer valid */
> > if (unlikely(!pskb_may_pull(skb, ihl)))
> > @@ -1233,7 +1235,7 @@ struct sk_buff *inet_gso_segment(struct sk_buff *skb,
> > fixedid = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TCP_FIXEDID);
> >
> > /* fixed ID is invalid if DF bit is not set */
> > - if (fixedid && !(iph->frag_off & htons(IP_DF)))
> > + if (fixedid && !(frag_off & htons(IP_DF)))
> > goto out;
> > }
> >
>
>
> I do not see why this patch would be needed ?
Where is iph being reloaded after that pskb_may_pull() and thus at line 1236 we
could use after free? The warning at line 1217?
1209 iph = ip_hdr(skb);
1210 ihl = iph->ihl * 4;
1211 if (ihl < sizeof(*iph))
1212 goto out;
1213
1214 id = ntohs(iph->id);
1215 proto = iph->protocol;
1216
1217 /* Warning: after this point, iph might be no longer valid */
1218 if (unlikely(!pskb_may_pull(skb, ihl)))
1219 goto out;
1220 __skb_pull(skb, ihl);
1221
1222 encap = SKB_GSO_CB(skb)->encap_level > 0;
1223 if (encap)
1224 features &= skb->dev->hw_enc_features;
1225 SKB_GSO_CB(skb)->encap_level += ihl;
1226
1227 skb_reset_transport_header(skb);
1228
1229 segs = ERR_PTR(-EPROTONOSUPPORT);
1230
1231 if (!skb->encapsulation || encap) {
1232 udpfrag = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP);
1233 fixedid = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TCP_FIXEDID);
1234
1235 /* fixed ID is invalid if DF bit is not set */
1236 if (fixedid && !(iph->frag_off & htons(IP_DF)))
1237 goto out;
1238 }
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH net] net/dccp: fix use-after-free in dccp_invalid_packet
2016-11-28 14:26 [PATCH net] net/dccp: fix use-after-free in dccp_invalid_packet Eric Dumazet
` (2 preceding siblings ...)
2016-11-28 15:05 ` Arnaldo Carvalho de Melo
@ 2016-11-28 15:20 ` Eric Dumazet
2016-11-28 15:36 ` Arnaldo Carvalho de Melo
2016-11-30 1:38 ` David Miller
5 siblings, 0 replies; 7+ messages in thread
From: Eric Dumazet @ 2016-11-28 15:20 UTC (permalink / raw)
To: dccp
On Mon, 2016-11-28 at 12:05 -0300, Arnaldo Carvalho de Melo wrote:
> Em Mon, Nov 28, 2016 at 06:47:14AM -0800, Eric Dumazet escreveu:
> > On Mon, 2016-11-28 at 11:40 -0300, Arnaldo Carvalho de Melo wrote:
> > > Em Mon, Nov 28, 2016 at 06:26:49AM -0800, Eric Dumazet escreveu:
> > > > From: Eric Dumazet <edumazet@google.com>
> > > >
> > > > pskb_may_pull() can reallocate skb->head, we need to reload dh pointer
> > > > in dccp_invalid_packet() or risk use after free.
> > > >
> > > > Bug found by Andrey Konovalov using syzkaller.
> > > >
> > > > Signed-off-by: Eric Dumazet <edumazet@google.com>
> > > > Reported-by: Andrey Konovalov <andreyknvl@google.com>
> > >
> > > Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> > >
> > > I was about to send exactly this patch, and while looking at it I think
> > > the patch below needs to go in as well, no? To follow the advice of that
> > > Warning line there :-)
> > >
> > > From: Arnaldo Carvalho de Melo <acme@redhat.com>
> > >
> > > pskb_may_pull() can reallocate skb->head, so we can't access
> > > iph->frag_off or risk use after free, save it to a variable and us that
> > > later.
> > >
> > > Cc: Andrey Konovalov <andreyknvl@google.com>
> > > Cc: Eric Dumazet <edumazet@google.com>
> > > Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> > >
> > > diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
> > > index 5ddf5cda07f4..9462070561a3 100644
> > > --- a/net/ipv4/af_inet.c
> > > +++ b/net/ipv4/af_inet.c
> > > @@ -1198,6 +1198,7 @@ struct sk_buff *inet_gso_segment(struct sk_buff *skb,
> > > struct iphdr *iph;
> > > int proto, tot_len;
> > > int nhoff;
> > > + u16 frag_off;
> > > int ihl;
> > > int id;
> > >
> > > @@ -1213,6 +1214,7 @@ struct sk_buff *inet_gso_segment(struct sk_buff *skb,
> > >
> > > id = ntohs(iph->id);
> > > proto = iph->protocol;
> > > + frag_off = iph->frag_off;
> > >
> > > /* Warning: after this point, iph might be no longer valid */
> > > if (unlikely(!pskb_may_pull(skb, ihl)))
> > > @@ -1233,7 +1235,7 @@ struct sk_buff *inet_gso_segment(struct sk_buff *skb,
> > > fixedid = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TCP_FIXEDID);
> > >
> > > /* fixed ID is invalid if DF bit is not set */
> > > - if (fixedid && !(iph->frag_off & htons(IP_DF)))
> > > + if (fixedid && !(frag_off & htons(IP_DF)))
> > > goto out;
> > > }
> > >
> >
> >
> > I do not see why this patch would be needed ?
>
> Where is iph being reloaded after that pskb_may_pull() and thus at line 1236 we
> could use after free? The warning at line 1217?
>
> 1209 iph = ip_hdr(skb);
> 1210 ihl = iph->ihl * 4;
> 1211 if (ihl < sizeof(*iph))
> 1212 goto out;
> 1213
> 1214 id = ntohs(iph->id);
> 1215 proto = iph->protocol;
> 1216
> 1217 /* Warning: after this point, iph might be no longer valid */
> 1218 if (unlikely(!pskb_may_pull(skb, ihl)))
> 1219 goto out;
> 1220 __skb_pull(skb, ihl);
> 1221
> 1222 encap = SKB_GSO_CB(skb)->encap_level > 0;
> 1223 if (encap)
> 1224 features &= skb->dev->hw_enc_features;
> 1225 SKB_GSO_CB(skb)->encap_level += ihl;
> 1226
> 1227 skb_reset_transport_header(skb);
> 1228
> 1229 segs = ERR_PTR(-EPROTONOSUPPORT);
> 1230
> 1231 if (!skb->encapsulation || encap) {
> 1232 udpfrag = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP);
> 1233 fixedid = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TCP_FIXEDID);
> 1234
> 1235 /* fixed ID is invalid if DF bit is not set */
> 1236 if (fixedid && !(iph->frag_off & htons(IP_DF)))
> 1237 goto out;
> 1238 }
>
Arg, I was looking at an old tree.
Please then add
Fixes: cbc53e08a793b ("GSO: Add GSO type for fixed IPv4 ID")
To ease stable backports.
Also, it looks comments are not read, we might kill this one and reload
iph.
( Saving 3 fields is now more expensive than simply reloading iph )
Thanks.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH net] net/dccp: fix use-after-free in dccp_invalid_packet
2016-11-28 14:26 [PATCH net] net/dccp: fix use-after-free in dccp_invalid_packet Eric Dumazet
` (3 preceding siblings ...)
2016-11-28 15:20 ` Eric Dumazet
@ 2016-11-28 15:36 ` Arnaldo Carvalho de Melo
2016-11-30 1:38 ` David Miller
5 siblings, 0 replies; 7+ messages in thread
From: Arnaldo Carvalho de Melo @ 2016-11-28 15:36 UTC (permalink / raw)
To: dccp
Em Mon, Nov 28, 2016 at 07:20:58AM -0800, Eric Dumazet escreveu:
> On Mon, 2016-11-28 at 12:05 -0300, Arnaldo Carvalho de Melo wrote:
> > Em Mon, Nov 28, 2016 at 06:47:14AM -0800, Eric Dumazet escreveu:
> > > On Mon, 2016-11-28 at 11:40 -0300, Arnaldo Carvalho de Melo wrote:
> > > > Em Mon, Nov 28, 2016 at 06:26:49AM -0800, Eric Dumazet escreveu:
> > > > > From: Eric Dumazet <edumazet@google.com>
> > > > >
> > > > > pskb_may_pull() can reallocate skb->head, we need to reload dh pointer
> > > > > in dccp_invalid_packet() or risk use after free.
> > > > >
> > > > > Bug found by Andrey Konovalov using syzkaller.
> > > > >
> > > > > Signed-off-by: Eric Dumazet <edumazet@google.com>
> > > > > Reported-by: Andrey Konovalov <andreyknvl@google.com>
> > > >
> > > > Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> > > >
> > > > I was about to send exactly this patch, and while looking at it I think
> > > > the patch below needs to go in as well, no? To follow the advice of that
> > > > Warning line there :-)
> > > >
> > > > From: Arnaldo Carvalho de Melo <acme@redhat.com>
> > > >
> > > > pskb_may_pull() can reallocate skb->head, so we can't access
> > > > iph->frag_off or risk use after free, save it to a variable and us that
> > > > later.
> > > >
> > > > Cc: Andrey Konovalov <andreyknvl@google.com>
> > > > Cc: Eric Dumazet <edumazet@google.com>
> > > > Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> > > >
> > > > diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
> > > > index 5ddf5cda07f4..9462070561a3 100644
> > > > --- a/net/ipv4/af_inet.c
> > > > +++ b/net/ipv4/af_inet.c
> > > > @@ -1198,6 +1198,7 @@ struct sk_buff *inet_gso_segment(struct sk_buff *skb,
> > > > struct iphdr *iph;
> > > > int proto, tot_len;
> > > > int nhoff;
> > > > + u16 frag_off;
> > > > int ihl;
> > > > int id;
> > > >
> > > > @@ -1213,6 +1214,7 @@ struct sk_buff *inet_gso_segment(struct sk_buff *skb,
> > > >
> > > > id = ntohs(iph->id);
> > > > proto = iph->protocol;
> > > > + frag_off = iph->frag_off;
> > > >
> > > > /* Warning: after this point, iph might be no longer valid */
> > > > if (unlikely(!pskb_may_pull(skb, ihl)))
> > > > @@ -1233,7 +1235,7 @@ struct sk_buff *inet_gso_segment(struct sk_buff *skb,
> > > > fixedid = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TCP_FIXEDID);
> > > >
> > > > /* fixed ID is invalid if DF bit is not set */
> > > > - if (fixedid && !(iph->frag_off & htons(IP_DF)))
> > > > + if (fixedid && !(frag_off & htons(IP_DF)))
> > > > goto out;
> > > > }
> > > >
> > >
> > >
> > > I do not see why this patch would be needed ?
> >
> > Where is iph being reloaded after that pskb_may_pull() and thus at line 1236 we
> > could use after free? The warning at line 1217?
> >
> > 1209 iph = ip_hdr(skb);
> > 1210 ihl = iph->ihl * 4;
> > 1211 if (ihl < sizeof(*iph))
> > 1212 goto out;
> > 1213
> > 1214 id = ntohs(iph->id);
> > 1215 proto = iph->protocol;
> > 1216
> > 1217 /* Warning: after this point, iph might be no longer valid */
> > 1218 if (unlikely(!pskb_may_pull(skb, ihl)))
> > 1219 goto out;
> > 1220 __skb_pull(skb, ihl);
> > 1221
> > 1222 encap = SKB_GSO_CB(skb)->encap_level > 0;
> > 1223 if (encap)
> > 1224 features &= skb->dev->hw_enc_features;
> > 1225 SKB_GSO_CB(skb)->encap_level += ihl;
> > 1226
> > 1227 skb_reset_transport_header(skb);
> > 1228
> > 1229 segs = ERR_PTR(-EPROTONOSUPPORT);
> > 1230
> > 1231 if (!skb->encapsulation || encap) {
> > 1232 udpfrag = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP);
> > 1233 fixedid = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TCP_FIXEDID);
> > 1234
> > 1235 /* fixed ID is invalid if DF bit is not set */
> > 1236 if (fixedid && !(iph->frag_off & htons(IP_DF)))
> > 1237 goto out;
> > 1238 }
> >
>
> Arg, I was looking at an old tree.
>
> Please then add
>
> Fixes: cbc53e08a793b ("GSO: Add GSO type for fixed IPv4 ID")
>
> To ease stable backports.
>
> Also, it looks comments are not read, we might kill this one and reload
> iph.
>
> ( Saving 3 fields is now more expensive than simply reloading iph )
Ok, I instead used ip_hdr(skb)->frag_off at that place, as it is the
only use after the pskb_may_pull(), right after that use it will reload
iph in another fashion anyway, sending the patch in another message,
holler if you disagree, i.e. nacking that ack 8-)
- Arnaldo
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH net] net/dccp: fix use-after-free in dccp_invalid_packet
2016-11-28 14:26 [PATCH net] net/dccp: fix use-after-free in dccp_invalid_packet Eric Dumazet
` (4 preceding siblings ...)
2016-11-28 15:36 ` Arnaldo Carvalho de Melo
@ 2016-11-30 1:38 ` David Miller
5 siblings, 0 replies; 7+ messages in thread
From: David Miller @ 2016-11-30 1:38 UTC (permalink / raw)
To: dccp
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Mon, 28 Nov 2016 06:26:49 -0800
> From: Eric Dumazet <edumazet@google.com>
>
> pskb_may_pull() can reallocate skb->head, we need to reload dh pointer
> in dccp_invalid_packet() or risk use after free.
>
> Bug found by Andrey Konovalov using syzkaller.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: Andrey Konovalov <andreyknvl@google.com>
Applied and queued up for -stable, thanks Eric.
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2016-11-30 1:38 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2016-11-28 14:26 [PATCH net] net/dccp: fix use-after-free in dccp_invalid_packet Eric Dumazet
2016-11-28 14:40 ` Arnaldo Carvalho de Melo
2016-11-28 14:47 ` Eric Dumazet
2016-11-28 15:05 ` Arnaldo Carvalho de Melo
2016-11-28 15:20 ` Eric Dumazet
2016-11-28 15:36 ` Arnaldo Carvalho de Melo
2016-11-30 1:38 ` David Miller
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