[PATCH net] ipv6: sr: Add unlikely hint to idev NULL check in seg6_hmac_validate

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* [PATCH net] ipv6: sr: Add unlikely hint to idev NULL check in seg6_hmac_validate_skb
@ 2026-03-11  7:23 Minhong He
  2026-03-11  8:57 ` Eric Dumazet
  0 siblings, 1 reply; 9+ messages in thread
From: Minhong He @ 2026-03-11  7:23 UTC (permalink / raw)
  To: andrea.mayer, davem, dsahern, edumazet, kuba, pabeni, horms,
	david.lebrun, netdev
  Cc: linux-kernel, Minhong He

In seg6_hmac_validate_skb(), the pointer returned by __in6_dev_get()
can theoretically be NULL if the network device lacks proper IPv6
initialization or is being torn down. However, this is an exceptional
error path; in normal operation, the device will always have a valid
inet6_dev structure.

Marking this NULL check with unlikely() helps the compiler optimize
branch prediction and code layout. It ensures that the common case
(valid idev) remains in the hot path, while the error handling code
is placed out of line, improving CPU pipeline efficiency for high-speed
SRv6 packet processing.

Fixes: bf355b8d2c30 ("ipv6: sr: add core files for SR HMAC support")
Signed-off-by: Minhong He <heminhong@kylinos.cn>
---
 net/ipv6/seg6_hmac.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv6/seg6_hmac.c b/net/ipv6/seg6_hmac.c
index ee6bac0160ac..a8f279ffb678 100644
--- a/net/ipv6/seg6_hmac.c
+++ b/net/ipv6/seg6_hmac.c
@@ -184,6 +184,8 @@ bool seg6_hmac_validate_skb(struct sk_buff *skb)
 	int require_hmac;

 	idev = __in6_dev_get(skb->dev);
+	if (unlikely(!idev))
+		return false;

 	srh = (struct ipv6_sr_hdr *)skb_transport_header(skb);

-- 
2.25.1

^ permalink raw reply related	[flat|nested] 9+ messages in thread

* Re: [PATCH net] ipv6: sr: Add unlikely hint to idev NULL check in seg6_hmac_validate_skb
  2026-03-11  7:23 [PATCH net] ipv6: sr: Add unlikely hint to idev NULL check in seg6_hmac_validate_skb Minhong He
@ 2026-03-11  8:57 ` Eric Dumazet
  2026-03-13  2:26   ` [PATCH net v2] ipv6: sr: Add NULL check for idev " Minhong He
  0 siblings, 1 reply; 9+ messages in thread
From: Eric Dumazet @ 2026-03-11  8:57 UTC (permalink / raw)
  To: Minhong He
  Cc: andrea.mayer, davem, dsahern, kuba, pabeni, horms, david.lebrun,
	netdev, linux-kernel

On Wed, Mar 11, 2026 at 8:23 AM Minhong He <heminhong@kylinos.cn> wrote:
>
> In seg6_hmac_validate_skb(), the pointer returned by __in6_dev_get()
> can theoretically be NULL if the network device lacks proper IPv6
> initialization or is being torn down. However, this is an exceptional
> error path; in normal operation, the device will always have a valid
> inet6_dev structure.
>
> Marking this NULL check with unlikely() helps the compiler optimize
> branch prediction and code layout. It ensures that the common case
> (valid idev) remains in the hot path, while the error handling code
> is placed out of line, improving CPU pipeline efficiency for high-speed
> SRv6 packet processing.

This section is unnecessary and dubious ?
Note that both clang and gcc already generate the correct code without
the unlikely()
So your claim about "CPU pipeline efficiency" is quite strange to me.

Let's keep the changelogs concise and focused on the real issue at hand.

Thanks.

> Fixes: bf355b8d2c30 ("ipv6: sr: add core files for SR HMAC support")
> Signed-off-by: Minhong He <heminhong@kylinos.cn>
> ---
>  net/ipv6/seg6_hmac.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/net/ipv6/seg6_hmac.c b/net/ipv6/seg6_hmac.c
> index ee6bac0160ac..a8f279ffb678 100644
> --- a/net/ipv6/seg6_hmac.c
> +++ b/net/ipv6/seg6_hmac.c
> @@ -184,6 +184,8 @@ bool seg6_hmac_validate_skb(struct sk_buff *skb)
>         int require_hmac;
>
>         idev = __in6_dev_get(skb->dev);
> +       if (unlikely(!idev))
> +               return false;
>
>         srh = (struct ipv6_sr_hdr *)skb_transport_header(skb);
>
> --
> 2.25.1
>

^ permalink raw reply	[flat|nested] 9+ messages in thread

* [PATCH net v2] ipv6: sr: Add NULL check for idev in seg6_hmac_validate_skb
  2026-03-11  8:57 ` Eric Dumazet
@ 2026-03-13  2:26   ` Minhong He
  2026-03-13  2:38     ` Jakub Kicinski
                       ` (2 more replies)
  0 siblings, 3 replies; 9+ messages in thread
From: Minhong He @ 2026-03-13  2:26 UTC (permalink / raw)
  To: edumazet
  Cc: andrea.mayer, davem, david.lebrun, dsahern, heminhong, horms,
	kuba, linux-kernel, netdev, pabeni

In seg6_hmac_validate_skb(), the pointer returned by __in6_dev_get()
can be NULL if the network device lacks proper IPv6 initialization
or is being torn down. Add a NULL check to avoid potential NULL pointer
dereference in subsequent code.

Fixes: bf355b8d2c30 ("ipv6: sr: add core files for SR HMAC support")
Signed-off-by: Minhong He <heminhong@kylinos.cn>
---
 net/ipv6/seg6_hmac.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv6/seg6_hmac.c b/net/ipv6/seg6_hmac.c
index ee6bac0160ac..e6964c6b0d38 100644
--- a/net/ipv6/seg6_hmac.c
+++ b/net/ipv6/seg6_hmac.c
@@ -184,6 +184,8 @@ bool seg6_hmac_validate_skb(struct sk_buff *skb)
 	int require_hmac;
 
 	idev = __in6_dev_get(skb->dev);
+	if (!idev)
+		return false;
 
 	srh = (struct ipv6_sr_hdr *)skb_transport_header(skb);
 
-- 
2.25.1


^ permalink raw reply related	[flat|nested] 9+ messages in thread

* Re: [PATCH net v2] ipv6: sr: Add NULL check for idev in seg6_hmac_validate_skb
  2026-03-13  2:26   ` [PATCH net v2] ipv6: sr: Add NULL check for idev " Minhong He
@ 2026-03-13  2:38     ` Jakub Kicinski
  2026-03-14 22:49     ` Andrea Mayer
  2026-03-15 16:01     ` [net,v2] " Simon Horman
  2 siblings, 0 replies; 9+ messages in thread
From: Jakub Kicinski @ 2026-03-13  2:38 UTC (permalink / raw)
  To: Minhong He
  Cc: edumazet, andrea.mayer, davem, david.lebrun, dsahern, horms,
	linux-kernel, netdev, pabeni

On Fri, 13 Mar 2026 10:26:34 +0800 Minhong He wrote:
> In seg6_hmac_validate_skb(), the pointer returned by __in6_dev_get()
> can be NULL if the network device lacks proper IPv6 initialization
> or is being torn down. Add a NULL check to avoid potential NULL pointer
> dereference in subsequent code.

next time please start a new thread instead of replying to the previous
posting please.

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: [PATCH net v2] ipv6: sr: Add NULL check for idev in seg6_hmac_validate_skb
  2026-03-13  2:26   ` [PATCH net v2] ipv6: sr: Add NULL check for idev " Minhong He
  2026-03-13  2:38     ` Jakub Kicinski
@ 2026-03-14 22:49     ` Andrea Mayer
  2026-03-15 16:01     ` [net,v2] " Simon Horman
  2 siblings, 0 replies; 9+ messages in thread
From: Andrea Mayer @ 2026-03-14 22:49 UTC (permalink / raw)
  To: Minhong He
  Cc: edumazet, davem, david.lebrun, dsahern, horms, kuba, linux-kernel,
	netdev, pabeni, stefano.salsano, Andrea Mayer

On Fri, 13 Mar 2026 10:26:34 +0800
Minhong He <heminhong@kylinos.cn> wrote:

> In seg6_hmac_validate_skb(), the pointer returned by __in6_dev_get()
> can be NULL if the network device lacks proper IPv6 initialization
> or is being torn down. Add a NULL check to avoid potential NULL pointer
> dereference in subsequent code.
> 
> Fixes: bf355b8d2c30 ("ipv6: sr: add core files for SR HMAC support")
> Signed-off-by: Minhong He <heminhong@kylinos.cn>
> ---
>  net/ipv6/seg6_hmac.c | 2 ++
>  1 file changed, 2 insertions(+)
> 

Hi Minhong,
Do you have a crash log or a way to reproduce this?

Thanks,
Andrea


> diff --git a/net/ipv6/seg6_hmac.c b/net/ipv6/seg6_hmac.c
> index ee6bac0160ac..e6964c6b0d38 100644
> --- a/net/ipv6/seg6_hmac.c
> +++ b/net/ipv6/seg6_hmac.c
> @@ -184,6 +184,8 @@ bool seg6_hmac_validate_skb(struct sk_buff *skb)
>  	int require_hmac;
>  
>  	idev = __in6_dev_get(skb->dev);
> +	if (!idev)
> +		return false;
>  
>  	srh = (struct ipv6_sr_hdr *)skb_transport_header(skb);
>  
> -- 
> 2.25.1
>

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: [net,v2] ipv6: sr: Add NULL check for idev in seg6_hmac_validate_skb
  2026-03-13  2:26   ` [PATCH net v2] ipv6: sr: Add NULL check for idev " Minhong He
  2026-03-13  2:38     ` Jakub Kicinski
  2026-03-14 22:49     ` Andrea Mayer
@ 2026-03-15 16:01     ` Simon Horman
  2026-03-16  7:33       ` [PATCH net v3] ipv6: add NULL checks for idev in SRv6 paths Minhong He
  2 siblings, 1 reply; 9+ messages in thread
From: Simon Horman @ 2026-03-15 16:01 UTC (permalink / raw)
  To: heminhong
  Cc: Simon Horman, davem, linux-kernel, netdev, dsahern, andrea.mayer,
	kuba, edumazet, david.lebrun, pabeni

This is an AI-generated review of your patch. The human sending this
email has considered the AI review valid, or at least plausible.

For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html
---
ipv6: sr: Add NULL check for idev in seg6_hmac_validate_skb

In seg6_hmac_validate_skb(), the pointer returned by __in6_dev_get()
can be NULL if the network device lacks proper IPv6 initialization
or is being torn down. Add a NULL check to avoid potential NULL pointer
dereference in subsequent code.

> diff --git a/net/ipv6/seg6_hmac.c b/net/ipv6/seg6_hmac.c
> --- a/net/ipv6/seg6_hmac.c
> +++ b/net/ipv6/seg6_hmac.c
> @@ -184,6 +184,8 @@ bool seg6_hmac_validate_skb(struct sk_buff *skb)
>  	int require_hmac;
>
>  	idev = __in6_dev_get(skb->dev);
> +	if (!idev)
> +		return false;
>
>  	srh = (struct ipv6_sr_hdr *)skb_transport_header(skb);
>

The patch adds a NULL check in seg6_hmac_validate_skb() to handle the
case when __in6_dev_get() returns NULL. However, does this fix the
complete issue?

Looking at ipv6_srh_rcv() in net/ipv6/exthdrs.c, there's an earlier use
of the same __in6_dev_get() call:

net/ipv6/exthdrs.c:ipv6_srh_rcv() {
    ...
    idev = __in6_dev_get(skb->dev);

    accept_seg6 = min(READ_ONCE(net->ipv6.devconf_all->seg6_enabled),
                      READ_ONCE(idev->cnf.seg6_enabled));
    ...
#ifdef CONFIG_IPV6_SEG6_HMAC
    if (!seg6_hmac_validate_skb(skb)) {
    ...
}

The idev pointer is dereferenced on line 384 (idev->cnf.seg6_enabled)
before seg6_hmac_validate_skb() is called. If __in6_dev_get() can return
NULL as the commit message states, wouldn't this cause a NULL pointer
dereference before the new check in seg6_hmac_validate_skb() has a
chance to catch it?

Should ipv6_srh_rcv() also check for NULL after calling __in6_dev_get()?

^ permalink raw reply	[flat|nested] 9+ messages in thread

* [PATCH net v3] ipv6: add NULL checks for idev in SRv6 paths
  2026-03-15 16:01     ` [net,v2] " Simon Horman
@ 2026-03-16  7:33       ` Minhong He
  2026-03-18  0:51         ` Andrea Mayer
  2026-03-19  0:44         ` patchwork-bot+netdevbpf
  0 siblings, 2 replies; 9+ messages in thread
From: Minhong He @ 2026-03-16  7:33 UTC (permalink / raw)
  To: horms
  Cc: andrea.mayer, davem, david.lebrun, dsahern, edumazet, heminhong,
	kuba, linux-kernel, netdev, pabeni

__in6_dev_get() can return NULL when the device has no IPv6 configuration
(e.g. MTU < IPV6_MIN_MTU or after NETDEV_UNREGISTER).

Add NULL checks for idev returned by __in6_dev_get() in both
seg6_hmac_validate_skb() and ipv6_srh_rcv() to prevent potential NULL
pointer dereferences.

Fixes: 1ababeba4a21 ("ipv6: implement dataplane support for rthdr type 4 (Segment Routing Header)")
Fixes: bf355b8d2c30 ("ipv6: sr: add core files for SR HMAC support")
Signed-off-by: Minhong He <heminhong@kylinos.cn>
---
 net/ipv6/exthdrs.c   | 4 ++++
 net/ipv6/seg6_hmac.c | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index 5e3610a926cf..95558fd6f447 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c
@@ -379,6 +379,10 @@ static int ipv6_srh_rcv(struct sk_buff *skb)
 	hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
 
 	idev = __in6_dev_get(skb->dev);
+	if (!idev) {
+		kfree_skb(skb);
+		return -1;
+	}
 
 	accept_seg6 = min(READ_ONCE(net->ipv6.devconf_all->seg6_enabled),
 			  READ_ONCE(idev->cnf.seg6_enabled));
diff --git a/net/ipv6/seg6_hmac.c b/net/ipv6/seg6_hmac.c
index ee6bac0160ac..e6964c6b0d38 100644
--- a/net/ipv6/seg6_hmac.c
+++ b/net/ipv6/seg6_hmac.c
@@ -184,6 +184,8 @@ bool seg6_hmac_validate_skb(struct sk_buff *skb)
 	int require_hmac;
 
 	idev = __in6_dev_get(skb->dev);
+	if (!idev)
+		return false;
 
 	srh = (struct ipv6_sr_hdr *)skb_transport_header(skb);
 
-- 
2.25.1


^ permalink raw reply related	[flat|nested] 9+ messages in thread

* Re: [PATCH net v3] ipv6: add NULL checks for idev in SRv6 paths
  2026-03-16  7:33       ` [PATCH net v3] ipv6: add NULL checks for idev in SRv6 paths Minhong He
@ 2026-03-18  0:51         ` Andrea Mayer
  2026-03-19  0:44         ` patchwork-bot+netdevbpf
  1 sibling, 0 replies; 9+ messages in thread
From: Andrea Mayer @ 2026-03-18  0:51 UTC (permalink / raw)
  To: Minhong He
  Cc: horms, davem, david.lebrun, dsahern, edumazet, kuba, linux-kernel,
	netdev, pabeni, stefano.salsano, Andrea Mayer

On Mon, 16 Mar 2026 15:33:01 +0800
Minhong He <heminhong@kylinos.cn> wrote:

> __in6_dev_get() can return NULL when the device has no IPv6 configuration
> (e.g. MTU < IPV6_MIN_MTU or after NETDEV_UNREGISTER).
> 
> Add NULL checks for idev returned by __in6_dev_get() in both
> seg6_hmac_validate_skb() and ipv6_srh_rcv() to prevent potential NULL
> pointer dereferences.
> 
> Fixes: 1ababeba4a21 ("ipv6: implement dataplane support for rthdr type 4 (Segment Routing Header)")
> Fixes: bf355b8d2c30 ("ipv6: sr: add core files for SR HMAC support")
> Signed-off-by: Minhong He <heminhong@kylinos.cn>
> ---

Hi Minhong,
 
I was able to trigger this with the MTU < IPV6_MIN_MTU scenario
while SRv6 traffic is in flight:

[ 2506.476833] ==================================================================
[ 2506.478368] BUG: KASAN: null-ptr-deref in ipv6_rthdr_rcv+0x7c7/0x1cc0
[ 2506.478368] Read of size 4 at addr 00000000000006a8 by task ping6/22207
[ 2506.478368]
[ 2506.478368] CPU: 0 UID: 0 PID: 22207 Comm: ping6 Not tainted 7.0.0-rc3-micro-vm-dev-00185-g43d222fbcdff #2176 PREEMPT(full)
[ 2506.478368] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
[ 2506.478368] Call Trace:
[ 2506.478368]  <IRQ>
[ 2506.478368]  dump_stack_lvl+0x7c/0xc0
[ 2506.478368]  print_report+0x3f1/0x5d0
[ 2506.478368]  ? __virt_addr_valid+0x24/0x340
[ 2506.478368]  ? ipv6_rthdr_rcv+0x7c7/0x1cc0
[ 2506.478368]  kasan_report+0x92/0xc0
[ 2506.478368]  ? ipv6_rthdr_rcv+0x7c7/0x1cc0
[ 2506.478368]  ipv6_rthdr_rcv+0x7c7/0x1cc0
[ 2506.478368]  ? __pfx_ipv6_rthdr_rcv+0x10/0x10
[ 2506.478368]  ? rcu_read_lock_held+0xac/0xc0
[ 2506.478368]  ? __pfx_rcu_read_lock_held+0x10/0x10
[ 2506.478368]  ? rcu_read_lock_held+0xac/0xc0
[ 2506.478368]  ? __pfx_rcu_read_lock_held+0x10/0x10
[ 2506.478368]  ? __rt6_find_exception_rcu+0x2c/0x200
[ 2506.478368]  ? kmem_cache_free+0xd0/0x530
[ 2506.478368]  ? icmpv6_rcv+0x4ec/0x10c0
[ 2506.478368]  ? ip6_protocol_deliver_rcu+0x93a/0xe20
[ 2506.478368]  ? find_held_lock+0x2d/0xa0
[ 2506.478368]  ? ip6_pol_route+0x1e3/0x7a0
[ 2506.478368]  ? __rcu_read_unlock+0x64/0x2f0
[ 2506.478368]  ? ip6_pol_route+0x1ed/0x7a0
[ 2506.478368]  ? __pfx_ip6_pol_route+0x10/0x10
[ 2506.478368]  ? __lock_acquire+0xb7f/0x1d30
[ 2506.478368]  ? kasan_quarantine_put+0x120/0x1c0
[ 2506.478368]  ? find_held_lock+0x2d/0xa0
[ 2506.478368]  ? rcu_read_lock_held+0xac/0xc0
[ 2506.478368]  ? __pfx_rcu_read_lock_held+0x10/0x10
[ 2506.478368]  ip6_protocol_deliver_rcu+0x93a/0xe20
[ 2506.478368]  ? rcu_read_lock_held+0xac/0xc0
[ 2506.478368]  ip6_input_finish+0x93/0x1a0
[ 2506.478368]  ip6_input+0xcd/0x480
[ 2506.478368]  ? __pfx_ip6_input+0x10/0x10
[ 2506.478368]  ? rcu_read_lock_held+0xac/0xc0
[ 2506.478368]  ? __pfx_rcu_read_lock_held+0x10/0x10
[ 2506.478368]  ? find_held_lock+0x2d/0xa0
[ 2506.478368]  ip6_rcv_finish+0x127/0x1d0
[ 2506.478368]  ? __pfx_ip6_rcv_finish+0x10/0x10
[ 2506.478368]  ? __pfx_ip6_input+0x10/0x10
[ 2506.478368]  ? sock_wfree+0x229/0x460
[ 2506.478368]  ? ip6_rcv_core.isra.19+0x5ea/0xcc0
[ 2506.478368]  ipv6_rcv+0xb4/0x330
[ 2506.478368]  ? __pfx_ipv6_rcv+0x10/0x10
[ 2506.478368]  ? __lock_acquire+0xb7f/0x1d30
[ 2506.478368]  ? __pfx_ipv6_rcv+0x10/0x10
[ 2506.478368]  __netif_receive_skb_one_core+0xe0/0x140
[ 2506.478368]  ? __pfx___netif_receive_skb_one_core+0x10/0x10
[ 2506.478368]  ? process_backlog+0x281/0x940
[ 2506.478368]  ? process_backlog+0x281/0x940
[ 2506.478368]  process_backlog+0x2c1/0x940
[ 2506.478368]  __napi_poll+0x57/0x3b0
[ 2506.478368]  net_rx_action+0x33f/0x710
[ 2506.478368]  ? __pfx_net_rx_action+0x10/0x10
[ 2506.478368]  ? rcu_nocb_unlock_irqrestore.isra.58+0x24/0x30
[ 2506.478368]  ? rcu_nocb_unlock_irqrestore.isra.58+0x24/0x30
[ 2506.478368]  ? lockdep_hardirqs_on+0xcc/0x150
[ 2506.478368]  ? rcu_do_batch+0x9e8/0xfa0
[ 2506.478368]  ? mark_held_locks+0x48/0x80
[ 2506.478368]  ? __pfx_rcu_do_batch+0x10/0x10
[ 2506.478368]  ? mark_held_locks+0x48/0x80
[ 2506.478368]  ? handle_softirqs+0xd8/0x680
[ 2506.478368]  handle_softirqs+0xf7/0x680
[ 2506.478368]  ? lwtunnel_output+0x9b/0x410
[ 2506.478368]  do_softirq.part.23+0x8f/0xd0
[ 2506.478368]  </IRQ>
[ 2506.478368]  <TASK>
[ 2506.478368]  __local_bh_enable_ip+0xe9/0xf0
[ 2506.478368]  lwtunnel_output+0xa0/0x410
[ 2506.478368]  ip6_local_out+0x15b/0x160
[ 2506.478368]  ? __pfx_ip6_local_out+0x10/0x10
[ 2506.478368]  ? __pfx_lwtunnel_output+0x10/0x10
[ 2506.478368]  ? __pfx_lwtunnel_output+0x10/0x10
[ 2506.478368]  ip6_send_skb+0x94/0x210
[ 2506.478368]  rawv6_sendmsg+0x10de/0x1340
[ 2506.478368]  ? down_read_non_owner+0xca/0x2f0
[ 2506.478368]  ? __pfx_rawv6_sendmsg+0x10/0x10
[ 2506.478368]  ? __mutex_unlock_slowpath+0x125/0x4f0
[ 2506.478368]  ? find_held_lock+0x2d/0xa0
[ 2506.478368]  ? __pfx_rcu_read_lock_any_held+0x10/0x10
[ 2506.478368]  ? __lock_acquire+0xb7f/0x1d30
[ 2506.478368]  ? n_tty_write+0x463/0x7d0
[ 2506.478368]  ? sock_has_perm+0x96/0x190
[ 2506.478368]  ? inet_send_prepare+0x16/0x290
[ 2506.478368]  ? __pfx_inet_sendmsg+0x10/0x10
[ 2506.478368]  ? __sock_sendmsg+0xd4/0xe0
[ 2506.478368]  __sock_sendmsg+0xd4/0xe0
[ 2506.478368]  __sys_sendto+0x18f/0x210
[ 2506.478368]  ? __pfx___sys_sendto+0x10/0x10
[ 2506.478368]  ? find_held_lock+0x2d/0xa0
[ 2506.478368]  ? __might_fault+0x6f/0xb0
[ 2506.478368]  ? __x64_sys_gettimeofday+0xe3/0x150
[ 2506.478368]  __x64_sys_sendto+0x6f/0x80
[ 2506.478368]  do_syscall_64+0xb3/0x5e0
[ 2506.478368]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
[ 2506.478368] RIP: 0033:0x7f23442319b7
[ 2506.478368] Code: 64 89 02 48 c7 c0 ff ff ff ff eb b6 0f 1f 80 00 00 00 00 48 8d 05 49 5d 0c 00 41 89 ca 8b 00 85 c0 75 10 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 71 c3 41 57 4d 89 c7 41 56 41 89 ce 41 55 49
[ 2506.478368] RSP: 002b:00007ffcde563fb8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
[ 2506.478368] RAX: ffffffffffffffda RBX: 000055bf4d595a20 RCX: 00007f23442319b7
[ 2506.478368] RDX: 0000000000000040 RSI: 000055bf4d595a20 RDI: 0000000000000003
[ 2506.478368] RBP: 0000000000000040 R08: 000055bf4d593940 R09: 000000000000001c
[ 2506.478368] R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffcde5652b8
[ 2506.478368] R13: 000055bf4d595a20 R14: 00007ffcde5640d0 R15: 000055bf4d5916a0
[ 2506.478368]  </TASK>
[ 2506.478368] ==================================================================


>  net/ipv6/exthdrs.c   | 4 ++++
>  net/ipv6/seg6_hmac.c | 2 ++
>  2 files changed, 6 insertions(+)
> 
> diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
> index 5e3610a926cf..95558fd6f447 100644
> --- a/net/ipv6/exthdrs.c
> +++ b/net/ipv6/exthdrs.c
> @@ -379,6 +379,10 @@ static int ipv6_srh_rcv(struct sk_buff *skb)
>  	hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
>  
>  	idev = __in6_dev_get(skb->dev);
> +	if (!idev) {
> +		kfree_skb(skb);
> +		return -1;
> +	}
>  
>  	accept_seg6 = min(READ_ONCE(net->ipv6.devconf_all->seg6_enabled),
>  			  READ_ONCE(idev->cnf.seg6_enabled));
> diff --git a/net/ipv6/seg6_hmac.c b/net/ipv6/seg6_hmac.c
> index ee6bac0160ac..e6964c6b0d38 100644
> --- a/net/ipv6/seg6_hmac.c
> +++ b/net/ipv6/seg6_hmac.c
> @@ -184,6 +184,8 @@ bool seg6_hmac_validate_skb(struct sk_buff *skb)
>  	int require_hmac;
>  
>  	idev = __in6_dev_get(skb->dev);
> +	if (!idev)
> +		return false;
>  
>  	srh = (struct ipv6_sr_hdr *)skb_transport_header(skb);
>  
> -- 
> 2.25.1
> 

The fixes look correct to me.

Nit: as shown by the trace above, the issue is not just potential
but actually reproducible.

Reviewed-by: Andrea Mayer <andrea.mayer@uniroma2.it>

Thanks,
Andrea

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: [PATCH net v3] ipv6: add NULL checks for idev in SRv6 paths
  2026-03-16  7:33       ` [PATCH net v3] ipv6: add NULL checks for idev in SRv6 paths Minhong He
  2026-03-18  0:51         ` Andrea Mayer
@ 2026-03-19  0:44         ` patchwork-bot+netdevbpf
  1 sibling, 0 replies; 9+ messages in thread
From: patchwork-bot+netdevbpf @ 2026-03-19  0:44 UTC (permalink / raw)
  To: Minhong He
  Cc: horms, andrea.mayer, davem, david.lebrun, dsahern, edumazet, kuba,
	linux-kernel, netdev, pabeni

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Mon, 16 Mar 2026 15:33:01 +0800 you wrote:
> __in6_dev_get() can return NULL when the device has no IPv6 configuration
> (e.g. MTU < IPV6_MIN_MTU or after NETDEV_UNREGISTER).
> 
> Add NULL checks for idev returned by __in6_dev_get() in both
> seg6_hmac_validate_skb() and ipv6_srh_rcv() to prevent potential NULL
> pointer dereferences.
> 
> [...]

Here is the summary with links:
  - [net,v3] ipv6: add NULL checks for idev in SRv6 paths
    https://git.kernel.org/netdev/net/c/064137935262

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html



^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2026-03-19  0:44 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-03-11  7:23 [PATCH net] ipv6: sr: Add unlikely hint to idev NULL check in seg6_hmac_validate_skb Minhong He
2026-03-11  8:57 ` Eric Dumazet
2026-03-13  2:26   ` [PATCH net v2] ipv6: sr: Add NULL check for idev " Minhong He
2026-03-13  2:38     ` Jakub Kicinski
2026-03-14 22:49     ` Andrea Mayer
2026-03-15 16:01     ` [net,v2] " Simon Horman
2026-03-16  7:33       ` [PATCH net v3] ipv6: add NULL checks for idev in SRv6 paths Minhong He
2026-03-18  0:51         ` Andrea Mayer
2026-03-19  0:44         ` patchwork-bot+netdevbpf

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