* [PATCH net-next] net: sched: fix TCF_LAYER_TRANSPORT handling in tcf_get_base_ptr()
@ 2025-11-21 15:41 Eric Dumazet
2025-11-21 17:07 ` Jamal Hadi Salim
2025-11-25 3:10 ` patchwork-bot+netdevbpf
0 siblings, 2 replies; 3+ messages in thread
From: Eric Dumazet @ 2025-11-21 15:41 UTC (permalink / raw)
To: David S . Miller, Jakub Kicinski, Paolo Abeni
Cc: Simon Horman, Jamal Hadi Salim, Cong Wang, Jiri Pirko, netdev,
eric.dumazet, Eric Dumazet, syzbot+f3a497f02c389d86ef16
syzbot reported that tcf_get_base_ptr() can be called while transport
header is not set [1].
Instead of returning a dangling pointer, return NULL.
Fix tcf_get_base_ptr() callers to handle this NULL value.
[1]
WARNING: CPU: 1 PID: 6019 at ./include/linux/skbuff.h:3071 skb_transport_header include/linux/skbuff.h:3071 [inline]
WARNING: CPU: 1 PID: 6019 at ./include/linux/skbuff.h:3071 tcf_get_base_ptr include/net/pkt_cls.h:539 [inline]
WARNING: CPU: 1 PID: 6019 at ./include/linux/skbuff.h:3071 em_nbyte_match+0x2d8/0x3f0 net/sched/em_nbyte.c:43
Modules linked in:
CPU: 1 UID: 0 PID: 6019 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Call Trace:
<TASK>
tcf_em_match net/sched/ematch.c:494 [inline]
__tcf_em_tree_match+0x1ac/0x770 net/sched/ematch.c:520
tcf_em_tree_match include/net/pkt_cls.h:512 [inline]
basic_classify+0x115/0x2d0 net/sched/cls_basic.c:50
tc_classify include/net/tc_wrapper.h:197 [inline]
__tcf_classify net/sched/cls_api.c:1764 [inline]
tcf_classify+0x4cf/0x1140 net/sched/cls_api.c:1860
multiq_classify net/sched/sch_multiq.c:39 [inline]
multiq_enqueue+0xfd/0x4c0 net/sched/sch_multiq.c:66
dev_qdisc_enqueue+0x4e/0x260 net/core/dev.c:4118
__dev_xmit_skb net/core/dev.c:4214 [inline]
__dev_queue_xmit+0xe83/0x3b50 net/core/dev.c:4729
packet_snd net/packet/af_packet.c:3076 [inline]
packet_sendmsg+0x3e33/0x5080 net/packet/af_packet.c:3108
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg+0x21c/0x270 net/socket.c:742
____sys_sendmsg+0x505/0x830 net/socket.c:2630
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: syzbot+f3a497f02c389d86ef16@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/6920855a.a70a0220.2ea503.0058.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
include/net/pkt_cls.h | 2 ++
net/sched/em_cmp.c | 5 ++++-
net/sched/em_nbyte.c | 2 ++
net/sched/em_text.c | 11 +++++++++--
4 files changed, 17 insertions(+), 3 deletions(-)
diff --git a/include/net/pkt_cls.h b/include/net/pkt_cls.h
index c64fd896b1f985c5f6a5b50cbb42ded640d0c9fe..99ac747b7906074c43b3eb8e34cf6c07235cc81d 100644
--- a/include/net/pkt_cls.h
+++ b/include/net/pkt_cls.h
@@ -536,6 +536,8 @@ static inline unsigned char * tcf_get_base_ptr(struct sk_buff *skb, int layer)
case TCF_LAYER_NETWORK:
return skb_network_header(skb);
case TCF_LAYER_TRANSPORT:
+ if (!skb_transport_header_was_set(skb))
+ break;
return skb_transport_header(skb);
}
diff --git a/net/sched/em_cmp.c b/net/sched/em_cmp.c
index 64b637f18bc7d40509bf5c9f7679cfbc2922af1c..48c1bce74f498d0b4ee3d1efde96459b0dac5896 100644
--- a/net/sched/em_cmp.c
+++ b/net/sched/em_cmp.c
@@ -22,9 +22,12 @@ static int em_cmp_match(struct sk_buff *skb, struct tcf_ematch *em,
struct tcf_pkt_info *info)
{
struct tcf_em_cmp *cmp = (struct tcf_em_cmp *) em->data;
- unsigned char *ptr = tcf_get_base_ptr(skb, cmp->layer) + cmp->off;
+ unsigned char *ptr = tcf_get_base_ptr(skb, cmp->layer);
u32 val = 0;
+ if (!ptr)
+ return 0;
+ ptr += cmp->off;
if (!tcf_valid_offset(skb, ptr, cmp->align))
return 0;
diff --git a/net/sched/em_nbyte.c b/net/sched/em_nbyte.c
index 4f9f21a05d5e40aadfdc4c339b8178ad43dc2c8b..c65ffa5fff946edbc30a65ad99087bf664665e32 100644
--- a/net/sched/em_nbyte.c
+++ b/net/sched/em_nbyte.c
@@ -42,6 +42,8 @@ static int em_nbyte_match(struct sk_buff *skb, struct tcf_ematch *em,
struct nbyte_data *nbyte = (struct nbyte_data *) em->data;
unsigned char *ptr = tcf_get_base_ptr(skb, nbyte->hdr.layer);
+ if (!ptr)
+ return 0;
ptr += nbyte->hdr.off;
if (!tcf_valid_offset(skb, ptr, nbyte->hdr.len))
diff --git a/net/sched/em_text.c b/net/sched/em_text.c
index 6b3d0af72c39c7fb1e3290e24bf94f5bf9e0b358..692e2be1793e9961bcd4516baf54a05341f6ac5d 100644
--- a/net/sched/em_text.c
+++ b/net/sched/em_text.c
@@ -29,12 +29,19 @@ static int em_text_match(struct sk_buff *skb, struct tcf_ematch *m,
struct tcf_pkt_info *info)
{
struct text_match *tm = EM_TEXT_PRIV(m);
+ unsigned char *ptr;
int from, to;
- from = tcf_get_base_ptr(skb, tm->from_layer) - skb->data;
+ ptr = tcf_get_base_ptr(skb, tm->from_layer);
+ if (!ptr)
+ return 0;
+ from = ptr - skb->data;
from += tm->from_offset;
- to = tcf_get_base_ptr(skb, tm->to_layer) - skb->data;
+ ptr = tcf_get_base_ptr(skb, tm->to_layer);
+ if (!ptr)
+ return 0;
+ to = ptr - skb->data;
to += tm->to_offset;
return skb_find_text(skb, from, to, tm->config) != UINT_MAX;
--
2.52.0.460.gd25c4c69ec-goog
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH net-next] net: sched: fix TCF_LAYER_TRANSPORT handling in tcf_get_base_ptr()
2025-11-21 15:41 [PATCH net-next] net: sched: fix TCF_LAYER_TRANSPORT handling in tcf_get_base_ptr() Eric Dumazet
@ 2025-11-21 17:07 ` Jamal Hadi Salim
2025-11-25 3:10 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: Jamal Hadi Salim @ 2025-11-21 17:07 UTC (permalink / raw)
To: Eric Dumazet
Cc: David S . Miller, Jakub Kicinski, Paolo Abeni, Simon Horman,
Cong Wang, Jiri Pirko, netdev, eric.dumazet,
syzbot+f3a497f02c389d86ef16
On Fri, Nov 21, 2025 at 10:41 AM Eric Dumazet <edumazet@google.com> wrote:
>
> syzbot reported that tcf_get_base_ptr() can be called while transport
> header is not set [1].
>
> Instead of returning a dangling pointer, return NULL.
>
> Fix tcf_get_base_ptr() callers to handle this NULL value.
>
> [1]
> WARNING: CPU: 1 PID: 6019 at ./include/linux/skbuff.h:3071 skb_transport_header include/linux/skbuff.h:3071 [inline]
> WARNING: CPU: 1 PID: 6019 at ./include/linux/skbuff.h:3071 tcf_get_base_ptr include/net/pkt_cls.h:539 [inline]
> WARNING: CPU: 1 PID: 6019 at ./include/linux/skbuff.h:3071 em_nbyte_match+0x2d8/0x3f0 net/sched/em_nbyte.c:43
> Modules linked in:
> CPU: 1 UID: 0 PID: 6019 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
> Call Trace:
> <TASK>
> tcf_em_match net/sched/ematch.c:494 [inline]
> __tcf_em_tree_match+0x1ac/0x770 net/sched/ematch.c:520
> tcf_em_tree_match include/net/pkt_cls.h:512 [inline]
> basic_classify+0x115/0x2d0 net/sched/cls_basic.c:50
> tc_classify include/net/tc_wrapper.h:197 [inline]
> __tcf_classify net/sched/cls_api.c:1764 [inline]
> tcf_classify+0x4cf/0x1140 net/sched/cls_api.c:1860
> multiq_classify net/sched/sch_multiq.c:39 [inline]
> multiq_enqueue+0xfd/0x4c0 net/sched/sch_multiq.c:66
> dev_qdisc_enqueue+0x4e/0x260 net/core/dev.c:4118
> __dev_xmit_skb net/core/dev.c:4214 [inline]
> __dev_queue_xmit+0xe83/0x3b50 net/core/dev.c:4729
> packet_snd net/packet/af_packet.c:3076 [inline]
> packet_sendmsg+0x3e33/0x5080 net/packet/af_packet.c:3108
> sock_sendmsg_nosec net/socket.c:727 [inline]
> __sock_sendmsg+0x21c/0x270 net/socket.c:742
> ____sys_sendmsg+0x505/0x830 net/socket.c:2630
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Reported-by: syzbot+f3a497f02c389d86ef16@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/netdev/6920855a.a70a0220.2ea503.0058.GAE@google.com/T/#u
> Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
cheers,
jamal
> ---
> include/net/pkt_cls.h | 2 ++
> net/sched/em_cmp.c | 5 ++++-
> net/sched/em_nbyte.c | 2 ++
> net/sched/em_text.c | 11 +++++++++--
> 4 files changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/include/net/pkt_cls.h b/include/net/pkt_cls.h
> index c64fd896b1f985c5f6a5b50cbb42ded640d0c9fe..99ac747b7906074c43b3eb8e34cf6c07235cc81d 100644
> --- a/include/net/pkt_cls.h
> +++ b/include/net/pkt_cls.h
> @@ -536,6 +536,8 @@ static inline unsigned char * tcf_get_base_ptr(struct sk_buff *skb, int layer)
> case TCF_LAYER_NETWORK:
> return skb_network_header(skb);
> case TCF_LAYER_TRANSPORT:
> + if (!skb_transport_header_was_set(skb))
> + break;
> return skb_transport_header(skb);
> }
>
> diff --git a/net/sched/em_cmp.c b/net/sched/em_cmp.c
> index 64b637f18bc7d40509bf5c9f7679cfbc2922af1c..48c1bce74f498d0b4ee3d1efde96459b0dac5896 100644
> --- a/net/sched/em_cmp.c
> +++ b/net/sched/em_cmp.c
> @@ -22,9 +22,12 @@ static int em_cmp_match(struct sk_buff *skb, struct tcf_ematch *em,
> struct tcf_pkt_info *info)
> {
> struct tcf_em_cmp *cmp = (struct tcf_em_cmp *) em->data;
> - unsigned char *ptr = tcf_get_base_ptr(skb, cmp->layer) + cmp->off;
> + unsigned char *ptr = tcf_get_base_ptr(skb, cmp->layer);
> u32 val = 0;
>
> + if (!ptr)
> + return 0;
> + ptr += cmp->off;
> if (!tcf_valid_offset(skb, ptr, cmp->align))
> return 0;
>
> diff --git a/net/sched/em_nbyte.c b/net/sched/em_nbyte.c
> index 4f9f21a05d5e40aadfdc4c339b8178ad43dc2c8b..c65ffa5fff946edbc30a65ad99087bf664665e32 100644
> --- a/net/sched/em_nbyte.c
> +++ b/net/sched/em_nbyte.c
> @@ -42,6 +42,8 @@ static int em_nbyte_match(struct sk_buff *skb, struct tcf_ematch *em,
> struct nbyte_data *nbyte = (struct nbyte_data *) em->data;
> unsigned char *ptr = tcf_get_base_ptr(skb, nbyte->hdr.layer);
>
> + if (!ptr)
> + return 0;
> ptr += nbyte->hdr.off;
>
> if (!tcf_valid_offset(skb, ptr, nbyte->hdr.len))
> diff --git a/net/sched/em_text.c b/net/sched/em_text.c
> index 6b3d0af72c39c7fb1e3290e24bf94f5bf9e0b358..692e2be1793e9961bcd4516baf54a05341f6ac5d 100644
> --- a/net/sched/em_text.c
> +++ b/net/sched/em_text.c
> @@ -29,12 +29,19 @@ static int em_text_match(struct sk_buff *skb, struct tcf_ematch *m,
> struct tcf_pkt_info *info)
> {
> struct text_match *tm = EM_TEXT_PRIV(m);
> + unsigned char *ptr;
> int from, to;
>
> - from = tcf_get_base_ptr(skb, tm->from_layer) - skb->data;
> + ptr = tcf_get_base_ptr(skb, tm->from_layer);
> + if (!ptr)
> + return 0;
> + from = ptr - skb->data;
> from += tm->from_offset;
>
> - to = tcf_get_base_ptr(skb, tm->to_layer) - skb->data;
> + ptr = tcf_get_base_ptr(skb, tm->to_layer);
> + if (!ptr)
> + return 0;
> + to = ptr - skb->data;
> to += tm->to_offset;
>
> return skb_find_text(skb, from, to, tm->config) != UINT_MAX;
> --
> 2.52.0.460.gd25c4c69ec-goog
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH net-next] net: sched: fix TCF_LAYER_TRANSPORT handling in tcf_get_base_ptr()
2025-11-21 15:41 [PATCH net-next] net: sched: fix TCF_LAYER_TRANSPORT handling in tcf_get_base_ptr() Eric Dumazet
2025-11-21 17:07 ` Jamal Hadi Salim
@ 2025-11-25 3:10 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: patchwork-bot+netdevbpf @ 2025-11-25 3:10 UTC (permalink / raw)
To: Eric Dumazet
Cc: davem, kuba, pabeni, horms, jhs, xiyou.wangcong, jiri, netdev,
eric.dumazet, syzbot+f3a497f02c389d86ef16
Hello:
This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:
On Fri, 21 Nov 2025 15:41:00 +0000 you wrote:
> syzbot reported that tcf_get_base_ptr() can be called while transport
> header is not set [1].
>
> Instead of returning a dangling pointer, return NULL.
>
> Fix tcf_get_base_ptr() callers to handle this NULL value.
>
> [...]
Here is the summary with links:
- [net-next] net: sched: fix TCF_LAYER_TRANSPORT handling in tcf_get_base_ptr()
https://git.kernel.org/netdev/net/c/4fe5a00ec707
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
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2025-11-21 15:41 [PATCH net-next] net: sched: fix TCF_LAYER_TRANSPORT handling in tcf_get_base_ptr() Eric Dumazet
2025-11-21 17:07 ` Jamal Hadi Salim
2025-11-25 3:10 ` patchwork-bot+netdevbpf
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