linux.git/net/sched, branch v6.16 Linux kernel source tree net/sched: sch_qfq: Avoid triggering might_sleep in atomic context in qfq_delete_class 2025-07-22T09:48:34+00:00 Xiang Mei xmei5@asu.edu 2025-07-17T23:01:28+00:00 cf074eca0065bc5142e6004ae236bb35a2687fdf might_sleep could be trigger in the atomic context in qfq_delete_class. qfq_destroy_class was moved into atomic context locked by sch_tree_lock to avoid a race condition bug on qfq_aggregate. However, might_sleep could be triggered by qfq_destroy_class, which introduced sleeping in atomic context (path: qfq_destroy_class->qdisc_put->__qdisc_destroy->lockdep_unregister_key ->might_sleep). Considering the race is on the qfq_aggregate objects, keeping qfq_rm_from_agg in the lock but moving the left part out can solve this issue. Fixes: 5e28d5a3f774 ("net/sched: sch_qfq: Fix race condition on qfq_aggregate") Reported-by: Dan Carpenter <dan.carpenter@linaro.org> Signed-off-by: Xiang Mei <xmei5@asu.edu> Link: https://patch.msgid.link/4a04e0cc-a64b-44e7-9213-2880ed641d77@sabinyo.mountain Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com> Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org> Link: https://patch.msgid.link/20250717230128.159766-1-xmei5@asu.edu Signed-off-by: Paolo Abeni <pabeni@redhat.com> 
might_sleep could be trigger in the atomic context in qfq_delete_class.

qfq_destroy_class was moved into atomic context locked
by sch_tree_lock to avoid a race condition bug on
qfq_aggregate. However, might_sleep could be triggered by
qfq_destroy_class, which introduced sleeping in atomic context (path:
qfq_destroy_class->qdisc_put->__qdisc_destroy->lockdep_unregister_key
->might_sleep).

Considering the race is on the qfq_aggregate objects, keeping
qfq_rm_from_agg in the lock but moving the left part out can solve
this issue.

Fixes: 5e28d5a3f774 ("net/sched: sch_qfq: Fix race condition on qfq_aggregate")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Xiang Mei <xmei5@asu.edu>
Link: https://patch.msgid.link/4a04e0cc-a64b-44e7-9213-2880ed641d77@sabinyo.mountain
Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://patch.msgid.link/20250717230128.159766-1-xmei5@asu.edu
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
net/sched: Return NULL when htb_lookup_leaf encounters an empty rbtree 2025-07-17T14:47:55+00:00 William Liu will@willsroot.io 2025-07-17T02:28:38+00:00 0e1d5d9b5c5966e2e42e298670808590db5ed628 htb_lookup_leaf has a BUG_ON that can trigger with the following: tc qdisc del dev lo root tc qdisc add dev lo root handle 1: htb default 1 tc class add dev lo parent 1: classid 1:1 htb rate 64bit tc qdisc add dev lo parent 1:1 handle 2: netem tc qdisc add dev lo parent 2:1 handle 3: blackhole ping -I lo -c1 -W0.001 127.0.0.1 The root cause is the following: 1. htb_dequeue calls htb_dequeue_tree which calls the dequeue handler on the selected leaf qdisc 2. netem_dequeue calls enqueue on the child qdisc 3. blackhole_enqueue drops the packet and returns a value that is not just NET_XMIT_SUCCESS 4. Because of this, netem_dequeue calls qdisc_tree_reduce_backlog, and since qlen is now 0, it calls htb_qlen_notify -> htb_deactivate -> htb_deactiviate_prios -> htb_remove_class_from_row -> htb_safe_rb_erase 5. As this is the only class in the selected hprio rbtree, __rb_change_child in __rb_erase_augmented sets the rb_root pointer to NULL 6. Because blackhole_dequeue returns NULL, netem_dequeue returns NULL, which causes htb_dequeue_tree to call htb_lookup_leaf with the same hprio rbtree, and fail the BUG_ON The function graph for this scenario is shown here: 0) | htb_enqueue() { 0) + 13.635 us | netem_enqueue(); 0) 4.719 us | htb_activate_prios(); 0) # 2249.199 us | } 0) | htb_dequeue() { 0) 2.355 us | htb_lookup_leaf(); 0) | netem_dequeue() { 0) + 11.061 us | blackhole_enqueue(); 0) | qdisc_tree_reduce_backlog() { 0) | qdisc_lookup_rcu() { 0) 1.873 us | qdisc_match_from_root(); 0) 6.292 us | } 0) 1.894 us | htb_search(); 0) | htb_qlen_notify() { 0) 2.655 us | htb_deactivate_prios(); 0) 6.933 us | } 0) + 25.227 us | } 0) 1.983 us | blackhole_dequeue(); 0) + 86.553 us | } 0) # 2932.761 us | qdisc_warn_nonwc(); 0) | htb_lookup_leaf() { 0) | BUG_ON(); ------------------------------------------ The full original bug report can be seen here [1]. We can fix this just by returning NULL instead of the BUG_ON, as htb_dequeue_tree returns NULL when htb_lookup_leaf returns NULL. [1] https://lore.kernel.org/netdev/pF5XOOIim0IuEfhI-SOxTgRvNoDwuux7UHKnE_Y5-zVd4wmGvNk2ceHjKb8ORnzw0cGwfmVu42g9dL7XyJLf1NEzaztboTWcm0Ogxuojoeo=@willsroot.io/ Fixes: 512bb43eb542 ("pkt_sched: sch_htb: Optimize WARN_ONs in htb_dequeue_tree() etc.") Signed-off-by: William Liu <will@willsroot.io> Signed-off-by: Savino Dicanosa <savy@syst3mfailure.io> Link: https://patch.msgid.link/20250717022816.221364-1-will@willsroot.io Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
htb_lookup_leaf has a BUG_ON that can trigger with the following:

tc qdisc del dev lo root
tc qdisc add dev lo root handle 1: htb default 1
tc class add dev lo parent 1: classid 1:1 htb rate 64bit
tc qdisc add dev lo parent 1:1 handle 2: netem
tc qdisc add dev lo parent 2:1 handle 3: blackhole
ping -I lo -c1 -W0.001 127.0.0.1

The root cause is the following:

1. htb_dequeue calls htb_dequeue_tree which calls the dequeue handler on
   the selected leaf qdisc
2. netem_dequeue calls enqueue on the child qdisc
3. blackhole_enqueue drops the packet and returns a value that is not
   just NET_XMIT_SUCCESS
4. Because of this, netem_dequeue calls qdisc_tree_reduce_backlog, and
   since qlen is now 0, it calls htb_qlen_notify -> htb_deactivate ->
   htb_deactiviate_prios -> htb_remove_class_from_row -> htb_safe_rb_erase
5. As this is the only class in the selected hprio rbtree,
   __rb_change_child in __rb_erase_augmented sets the rb_root pointer to
   NULL
6. Because blackhole_dequeue returns NULL, netem_dequeue returns NULL,
   which causes htb_dequeue_tree to call htb_lookup_leaf with the same
   hprio rbtree, and fail the BUG_ON

The function graph for this scenario is shown here:
 0)               |  htb_enqueue() {
 0) + 13.635 us   |    netem_enqueue();
 0)   4.719 us    |    htb_activate_prios();
 0) # 2249.199 us |  }
 0)               |  htb_dequeue() {
 0)   2.355 us    |    htb_lookup_leaf();
 0)               |    netem_dequeue() {
 0) + 11.061 us   |      blackhole_enqueue();
 0)               |      qdisc_tree_reduce_backlog() {
 0)               |        qdisc_lookup_rcu() {
 0)   1.873 us    |          qdisc_match_from_root();
 0)   6.292 us    |        }
 0)   1.894 us    |        htb_search();
 0)               |        htb_qlen_notify() {
 0)   2.655 us    |          htb_deactivate_prios();
 0)   6.933 us    |        }
 0) + 25.227 us   |      }
 0)   1.983 us    |      blackhole_dequeue();
 0) + 86.553 us   |    }
 0) # 2932.761 us |    qdisc_warn_nonwc();
 0)               |    htb_lookup_leaf() {
 0)               |      BUG_ON();
 ------------------------------------------

The full original bug report can be seen here [1].

We can fix this just by returning NULL instead of the BUG_ON,
as htb_dequeue_tree returns NULL when htb_lookup_leaf returns
NULL.

[1] https://lore.kernel.org/netdev/pF5XOOIim0IuEfhI-SOxTgRvNoDwuux7UHKnE_Y5-zVd4wmGvNk2ceHjKb8ORnzw0cGwfmVu42g9dL7XyJLf1NEzaztboTWcm0Ogxuojoeo=@willsroot.io/

Fixes: 512bb43eb542 ("pkt_sched: sch_htb: Optimize WARN_ONs in htb_dequeue_tree() etc.")
Signed-off-by: William Liu <will@willsroot.io>
Signed-off-by: Savino Dicanosa <savy@syst3mfailure.io>
Link: https://patch.msgid.link/20250717022816.221364-1-will@willsroot.io
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net/sched: sch_qfq: Fix race condition on qfq_aggregate 2025-07-12T23:09:33+00:00 Xiang Mei xmei5@asu.edu 2025-07-10T10:09:42+00:00 5e28d5a3f774f118896aec17a3a20a9c5c9dfc64 A race condition can occur when 'agg' is modified in qfq_change_agg (called during qfq_enqueue) while other threads access it concurrently. For example, qfq_dump_class may trigger a NULL dereference, and qfq_delete_class may cause a use-after-free. This patch addresses the issue by: 1. Moved qfq_destroy_class into the critical section. 2. Added sch_tree_lock protection to qfq_dump_class and qfq_dump_class_stats. Fixes: 462dbc9101ac ("pkt_sched: QFQ Plus: fair-queueing service at DRR cost") Signed-off-by: Xiang Mei <xmei5@asu.edu> Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
A race condition can occur when 'agg' is modified in qfq_change_agg
(called during qfq_enqueue) while other threads access it
concurrently. For example, qfq_dump_class may trigger a NULL
dereference, and qfq_delete_class may cause a use-after-free.

This patch addresses the issue by:

1. Moved qfq_destroy_class into the critical section.

2. Added sch_tree_lock protection to qfq_dump_class and
qfq_dump_class_stats.

Fixes: 462dbc9101ac ("pkt_sched: QFQ Plus: fair-queueing service at DRR cost")
Signed-off-by: Xiang Mei <xmei5@asu.edu>
Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/sched: sch_qfq: Fix null-deref in agg_dequeue 2025-07-10T09:08:35+00:00 Xiang Mei xmei5@asu.edu 2025-07-05T21:21:43+00:00 dd831ac8221e691e9e918585b1003c7071df0379 To prevent a potential crash in agg_dequeue (net/sched/sch_qfq.c) when cl->qdisc->ops->peek(cl->qdisc) returns NULL, we check the return value before using it, similar to the existing approach in sch_hfsc.c. To avoid code duplication, the following changes are made: 1. Changed qdisc_warn_nonwc(include/net/pkt_sched.h) into a static inline function. 2. Moved qdisc_peek_len from net/sched/sch_hfsc.c to include/net/pkt_sched.h so that sch_qfq can reuse it. 3. Applied qdisc_peek_len in agg_dequeue to avoid crashing. Signed-off-by: Xiang Mei <xmei5@asu.edu> Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com> Link: https://patch.msgid.link/20250705212143.3982664-1-xmei5@asu.edu Signed-off-by: Paolo Abeni <pabeni@redhat.com> 
To prevent a potential crash in agg_dequeue (net/sched/sch_qfq.c)
when cl->qdisc->ops->peek(cl->qdisc) returns NULL, we check the return
value before using it, similar to the existing approach in sch_hfsc.c.

To avoid code duplication, the following changes are made:

1. Changed qdisc_warn_nonwc(include/net/pkt_sched.h) into a static
inline function.

2. Moved qdisc_peek_len from net/sched/sch_hfsc.c to
include/net/pkt_sched.h so that sch_qfq can reuse it.

3. Applied qdisc_peek_len in agg_dequeue to avoid crashing.

Signed-off-by: Xiang Mei <xmei5@asu.edu>
Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Link: https://patch.msgid.link/20250705212143.3982664-1-xmei5@asu.edu
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
net/sched: Abort __tc_modify_qdisc if parent class does not exist 2025-07-10T02:23:25+00:00 Victor Nogueira victor@mojatatu.com 2025-07-07T21:08:01+00:00 ffdde7bf5a439aaa1955ebd581f5c64ab1533963 Lion's patch [1] revealed an ancient bug in the qdisc API. Whenever a user creates/modifies a qdisc specifying as a parent another qdisc, the qdisc API will, during grafting, detect that the user is not trying to attach to a class and reject. However grafting is performed after qdisc_create (and thus the qdiscs' init callback) is executed. In qdiscs that eventually call qdisc_tree_reduce_backlog during init or change (such as fq, hhf, choke, etc), an issue arises. For example, executing the following commands: sudo tc qdisc add dev lo root handle a: htb default 2 sudo tc qdisc add dev lo parent a: handle beef fq Qdiscs such as fq, hhf, choke, etc unconditionally invoke qdisc_tree_reduce_backlog() in their control path init() or change() which then causes a failure to find the child class; however, that does not stop the unconditional invocation of the assumed child qdisc's qlen_notify with a null class. All these qdiscs make the assumption that class is non-null. The solution is ensure that qdisc_leaf() which looks up the parent class, and is invoked prior to qdisc_create(), should return failure on not finding the class. In this patch, we leverage qdisc_leaf to return ERR_PTRs whenever the parentid doesn't correspond to a class, so that we can detect it earlier on and abort before qdisc_create is called. [1] https://lore.kernel.org/netdev/d912cbd7-193b-4269-9857-525bee8bbb6a@gmail.com/ Fixes: 5e50da01d0ce ("[NET_SCHED]: Fix endless loops (part 2): "simple" qdiscs") Reported-by: syzbot+d8b58d7b0ad89a678a16@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/68663c93.a70a0220.5d25f.0857.GAE@google.com/ Reported-by: syzbot+5eccb463fa89309d8bdc@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/68663c94.a70a0220.5d25f.0858.GAE@google.com/ Reported-by: syzbot+1261670bbdefc5485a06@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/686764a5.a00a0220.c7b3.0013.GAE@google.com/ Reported-by: syzbot+15b96fc3aac35468fe77@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/686764a5.a00a0220.c7b3.0014.GAE@google.com/ Reported-by: syzbot+4dadc5aecf80324d5a51@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/68679e81.a70a0220.29cf51.0016.GAE@google.com/ Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: Victor Nogueira <victor@mojatatu.com> Link: https://patch.msgid.link/20250707210801.372995-1-victor@mojatatu.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
Lion's patch [1] revealed an ancient bug in the qdisc API.
Whenever a user creates/modifies a qdisc specifying as a parent another
qdisc, the qdisc API will, during grafting, detect that the user is
not trying to attach to a class and reject. However grafting is
performed after qdisc_create (and thus the qdiscs' init callback) is
executed. In qdiscs that eventually call qdisc_tree_reduce_backlog
during init or change (such as fq, hhf, choke, etc), an issue
arises. For example, executing the following commands:

sudo tc qdisc add dev lo root handle a: htb default 2
sudo tc qdisc add dev lo parent a: handle beef fq

Qdiscs such as fq, hhf, choke, etc unconditionally invoke
qdisc_tree_reduce_backlog() in their control path init() or change() which
then causes a failure to find the child class; however, that does not stop
the unconditional invocation of the assumed child qdisc's qlen_notify with
a null class. All these qdiscs make the assumption that class is non-null.

The solution is ensure that qdisc_leaf() which looks up the parent
class, and is invoked prior to qdisc_create(), should return failure on
not finding the class.
In this patch, we leverage qdisc_leaf to return ERR_PTRs whenever the
parentid doesn't correspond to a class, so that we can detect it
earlier on and abort before qdisc_create is called.

[1] https://lore.kernel.org/netdev/d912cbd7-193b-4269-9857-525bee8bbb6a@gmail.com/

Fixes: 5e50da01d0ce ("[NET_SCHED]: Fix endless loops (part 2): "simple" qdiscs")
Reported-by: syzbot+d8b58d7b0ad89a678a16@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/68663c93.a70a0220.5d25f.0857.GAE@google.com/
Reported-by: syzbot+5eccb463fa89309d8bdc@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/68663c94.a70a0220.5d25f.0858.GAE@google.com/
Reported-by: syzbot+1261670bbdefc5485a06@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/686764a5.a00a0220.c7b3.0013.GAE@google.com/
Reported-by: syzbot+15b96fc3aac35468fe77@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/686764a5.a00a0220.c7b3.0014.GAE@google.com/
Reported-by: syzbot+4dadc5aecf80324d5a51@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/68679e81.a70a0220.29cf51.0016.GAE@google.com/
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Victor Nogueira <victor@mojatatu.com>
Link: https://patch.msgid.link/20250707210801.372995-1-victor@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net/sched: Always pass notifications when child class becomes empty 2025-07-02T21:42:17+00:00 Lion Ackermann nnamrec@gmail.com 2025-06-30T13:27:30+00:00 103406b38c600fec1fe375a77b27d87e314aea09 Certain classful qdiscs may invoke their classes' dequeue handler on an enqueue operation. This may unexpectedly empty the child qdisc and thus make an in-flight class passive via qlen_notify(). Most qdiscs do not expect such behaviour at this point in time and may re-activate the class eventually anyways which will lead to a use-after-free. The referenced fix commit attempted to fix this behavior for the HFSC case by moving the backlog accounting around, though this turned out to be incomplete since the parent's parent may run into the issue too. The following reproducer demonstrates this use-after-free: tc qdisc add dev lo root handle 1: drr tc filter add dev lo parent 1: basic classid 1:1 tc class add dev lo parent 1: classid 1:1 drr tc qdisc add dev lo parent 1:1 handle 2: hfsc def 1 tc class add dev lo parent 2: classid 2:1 hfsc rt m1 8 d 1 m2 0 tc qdisc add dev lo parent 2:1 handle 3: netem tc qdisc add dev lo parent 3:1 handle 4: blackhole echo 1 | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888 tc class delete dev lo classid 1:1 echo 1 | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888 Since backlog accounting issues leading to a use-after-frees on stale class pointers is a recurring pattern at this point, this patch takes a different approach. Instead of trying to fix the accounting, the patch ensures that qdisc_tree_reduce_backlog always calls qlen_notify when the child qdisc is empty. This solves the problem because deletion of qdiscs always involves a call to qdisc_reset() and / or qdisc_purge_queue() which ultimately resets its qlen to 0 thus causing the following qdisc_tree_reduce_backlog() to report to the parent. Note that this may call qlen_notify on passive classes multiple times. This is not a problem after the recent patch series that made all the classful qdiscs qlen_notify() handlers idempotent. Fixes: 3f981138109f ("sch_hfsc: Fix qlen accounting bug when using peek in hfsc_enqueue()") Signed-off-by: Lion Ackermann <nnamrec@gmail.com> Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com> Acked-by: Cong Wang <xiyou.wangcong@gmail.com> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Link: https://patch.msgid.link/d912cbd7-193b-4269-9857-525bee8bbb6a@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
Certain classful qdiscs may invoke their classes' dequeue handler on an
enqueue operation. This may unexpectedly empty the child qdisc and thus
make an in-flight class passive via qlen_notify(). Most qdiscs do not
expect such behaviour at this point in time and may re-activate the
class eventually anyways which will lead to a use-after-free.

The referenced fix commit attempted to fix this behavior for the HFSC
case by moving the backlog accounting around, though this turned out to
be incomplete since the parent's parent may run into the issue too.
The following reproducer demonstrates this use-after-free:

    tc qdisc add dev lo root handle 1: drr
    tc filter add dev lo parent 1: basic classid 1:1
    tc class add dev lo parent 1: classid 1:1 drr
    tc qdisc add dev lo parent 1:1 handle 2: hfsc def 1
    tc class add dev lo parent 2: classid 2:1 hfsc rt m1 8 d 1 m2 0
    tc qdisc add dev lo parent 2:1 handle 3: netem
    tc qdisc add dev lo parent 3:1 handle 4: blackhole

    echo 1 | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888
    tc class delete dev lo classid 1:1
    echo 1 | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888

Since backlog accounting issues leading to a use-after-frees on stale
class pointers is a recurring pattern at this point, this patch takes
a different approach. Instead of trying to fix the accounting, the patch
ensures that qdisc_tree_reduce_backlog always calls qlen_notify when
the child qdisc is empty. This solves the problem because deletion of
qdiscs always involves a call to qdisc_reset() and / or
qdisc_purge_queue() which ultimately resets its qlen to 0 thus causing
the following qdisc_tree_reduce_backlog() to report to the parent. Note
that this may call qlen_notify on passive classes multiple times. This
is not a problem after the recent patch series that made all the
classful qdiscs qlen_notify() handlers idempotent.

Fixes: 3f981138109f ("sch_hfsc: Fix qlen accounting bug when using peek in hfsc_enqueue()")
Signed-off-by: Lion Ackermann <nnamrec@gmail.com>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/d912cbd7-193b-4269-9857-525bee8bbb6a@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net/sched: fix use-after-free in taprio_dev_notifier 2025-06-17T23:14:04+00:00 Hyunwoo Kim imv4bel@gmail.com 2025-06-14T00:54:57+00:00 b160766e26d4e2e2d6fe2294e0b02f92baefcec5 Since taprio’s taprio_dev_notifier() isn’t protected by an RCU read-side critical section, a race with advance_sched() can lead to a use-after-free. Adding rcu_read_lock() inside taprio_dev_notifier() prevents this. Fixes: fed87cc6718a ("net/sched: taprio: automatically calculate queueMaxSDU based on TC gate durations") Cc: stable@vger.kernel.org Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com> Reviewed-by: Simon Horman <horms@kernel.org> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/aEzIYYxt0is9upYG@v4bel-B760M-AORUS-ELITE-AX Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
Since taprio’s taprio_dev_notifier() isn’t protected by an
RCU read-side critical section, a race with advance_sched()
can lead to a use-after-free.

Adding rcu_read_lock() inside taprio_dev_notifier() prevents this.

Fixes: fed87cc6718a ("net/sched: taprio: automatically calculate queueMaxSDU based on TC gate durations")
Cc: stable@vger.kernel.org
Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/aEzIYYxt0is9upYG@v4bel-B760M-AORUS-ELITE-AX
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Merge tag 'net-6.16-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-06-12T16:50:36+00:00 Linus Torvalds torvalds@linux-foundation.org 2025-06-12T16:50:36+00:00 27605c8c0f69e319df156b471974e4e223035378 Pull networking fixes from Jakub Kicinski: "Including fixes from bluetooth and wireless. Current release - regressions: - af_unix: allow passing cred for embryo without SO_PASSCRED/SO_PASSPIDFD Current release - new code bugs: - eth: airoha: correct enable mask for RX queues 16-31 - veth: prevent NULL pointer dereference in veth_xdp_rcv when peer disappears under traffic - ipv6: move fib6_config_validate() to ip6_route_add(), prevent invalid routes Previous releases - regressions: - phy: phy_caps: don't skip better duplex match on non-exact match - dsa: b53: fix untagged traffic sent via cpu tagged with VID 0 - Revert "wifi: mwifiex: Fix HT40 bandwidth issue.", it caused transient packet loss, exact reason not fully understood, yet Previous releases - always broken: - net: clear the dst when BPF is changing skb protocol (IPv4 <> IPv6) - sched: sfq: fix a potential crash on gso_skb handling - Bluetooth: intel: improve rx buffer posting to avoid causing issues in the firmware - eth: intel: i40e: make reset handling robust against multiple requests - eth: mlx5: ensure FW pages are always allocated on the local NUMA node, even when device is configure to 'serve' another node - wifi: ath12k: fix GCC_GCC_PCIE_HOT_RST definition for WCN7850, prevent kernel crashes - wifi: ath11k: avoid burning CPU in ath11k_debugfs_fw_stats_request() for 3 sec if fw_stats_done is not set" * tag 'net-6.16-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (70 commits) selftests: drv-net: rss_ctx: Add test for ntuple rules targeting default RSS context net: ethtool: Don't check if RSS context exists in case of context 0 af_unix: Allow passing cred for embryo without SO_PASSCRED/SO_PASSPIDFD. ipv6: Move fib6_config_validate() to ip6_route_add(). net: drv: netdevsim: don't napi_complete() from netpoll net/mlx5: HWS, Add error checking to hws_bwc_rule_complex_hash_node_get() veth: prevent NULL pointer dereference in veth_xdp_rcv net_sched: remove qdisc_tree_flush_backlog() net_sched: ets: fix a race in ets_qdisc_change() net_sched: tbf: fix a race in tbf_change() net_sched: red: fix a race in __red_change() net_sched: prio: fix a race in prio_tune() net_sched: sch_sfq: reject invalid perturb period net: phy: phy_caps: Don't skip better duplex macth on non-exact match MAINTAINERS: Update Kuniyuki Iwashima's email address. selftests: net: add test case for NAT46 looping back dst net: clear the dst when changing skb protocol net/mlx5e: Fix number of lanes to UNKNOWN when using data_rate_oper net/mlx5e: Fix leak of Geneve TLV option object net/mlx5: HWS, make sure the uplink is the last destination ... 
Pull networking fixes from Jakub Kicinski:
 "Including fixes from bluetooth and wireless.

  Current release - regressions:

   - af_unix: allow passing cred for embryo without SO_PASSCRED/SO_PASSPIDFD

  Current release - new code bugs:

   - eth: airoha: correct enable mask for RX queues 16-31

   - veth: prevent NULL pointer dereference in veth_xdp_rcv when peer
     disappears under traffic

   - ipv6: move fib6_config_validate() to ip6_route_add(), prevent
     invalid routes

  Previous releases - regressions:

   - phy: phy_caps: don't skip better duplex match on non-exact match

   - dsa: b53: fix untagged traffic sent via cpu tagged with VID 0

   - Revert "wifi: mwifiex: Fix HT40 bandwidth issue.", it caused
     transient packet loss, exact reason not fully understood, yet

  Previous releases - always broken:

   - net: clear the dst when BPF is changing skb protocol (IPv4 <> IPv6)

   - sched: sfq: fix a potential crash on gso_skb handling

   - Bluetooth: intel: improve rx buffer posting to avoid causing issues
     in the firmware

   - eth: intel: i40e: make reset handling robust against multiple
     requests

   - eth: mlx5: ensure FW pages are always allocated on the local NUMA
     node, even when device is configure to 'serve' another node

   - wifi: ath12k: fix GCC_GCC_PCIE_HOT_RST definition for WCN7850,
     prevent kernel crashes

   - wifi: ath11k: avoid burning CPU in ath11k_debugfs_fw_stats_request()
     for 3 sec if fw_stats_done is not set"

* tag 'net-6.16-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (70 commits)
  selftests: drv-net: rss_ctx: Add test for ntuple rules targeting default RSS context
  net: ethtool: Don't check if RSS context exists in case of context 0
  af_unix: Allow passing cred for embryo without SO_PASSCRED/SO_PASSPIDFD.
  ipv6: Move fib6_config_validate() to ip6_route_add().
  net: drv: netdevsim: don't napi_complete() from netpoll
  net/mlx5: HWS, Add error checking to hws_bwc_rule_complex_hash_node_get()
  veth: prevent NULL pointer dereference in veth_xdp_rcv
  net_sched: remove qdisc_tree_flush_backlog()
  net_sched: ets: fix a race in ets_qdisc_change()
  net_sched: tbf: fix a race in tbf_change()
  net_sched: red: fix a race in __red_change()
  net_sched: prio: fix a race in prio_tune()
  net_sched: sch_sfq: reject invalid perturb period
  net: phy: phy_caps: Don't skip better duplex macth on non-exact match
  MAINTAINERS: Update Kuniyuki Iwashima's email address.
  selftests: net: add test case for NAT46 looping back dst
  net: clear the dst when changing skb protocol
  net/mlx5e: Fix number of lanes to UNKNOWN when using data_rate_oper
  net/mlx5e: Fix leak of Geneve TLV option object
  net/mlx5: HWS, make sure the uplink is the last destination
  ...
net_sched: ets: fix a race in ets_qdisc_change() 2025-06-12T15:05:50+00:00 Eric Dumazet edumazet@google.com 2025-06-11T11:15:14+00:00 d92adacdd8c2960be856e0b82acc5b7c5395fddb Gerrard Tai reported a race condition in ETS, whenever SFQ perturb timer fires at the wrong time. The race is as follows: CPU 0 CPU 1 [1]: lock root [2]: qdisc_tree_flush_backlog() [3]: unlock root | | [5]: lock root | [6]: rehash | [7]: qdisc_tree_reduce_backlog() | [4]: qdisc_put() This can be abused to underflow a parent's qlen. Calling qdisc_purge_queue() instead of qdisc_tree_flush_backlog() should fix the race, because all packets will be purged from the qdisc before releasing the lock. Fixes: b05972f01e7d ("net: sched: tbf: don't call qdisc_put() while holding tree lock") Reported-by: Gerrard Tai <gerrard.tai@starlabs.sg> Suggested-by: Gerrard Tai <gerrard.tai@starlabs.sg> Signed-off-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250611111515.1983366-5-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
Gerrard Tai reported a race condition in ETS, whenever SFQ perturb timer
fires at the wrong time.

The race is as follows:

CPU 0                                 CPU 1
[1]: lock root
[2]: qdisc_tree_flush_backlog()
[3]: unlock root
 |
 |                                    [5]: lock root
 |                                    [6]: rehash
 |                                    [7]: qdisc_tree_reduce_backlog()
 |
[4]: qdisc_put()

This can be abused to underflow a parent's qlen.

Calling qdisc_purge_queue() instead of qdisc_tree_flush_backlog()
should fix the race, because all packets will be purged from the qdisc
before releasing the lock.

Fixes: b05972f01e7d ("net: sched: tbf: don't call qdisc_put() while holding tree lock")
Reported-by: Gerrard Tai <gerrard.tai@starlabs.sg>
Suggested-by: Gerrard Tai <gerrard.tai@starlabs.sg>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250611111515.1983366-5-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net_sched: tbf: fix a race in tbf_change() 2025-06-12T15:05:50+00:00 Eric Dumazet edumazet@google.com 2025-06-11T11:15:13+00:00 43eb466041216d25dedaef1c383ad7bd89929cbc Gerrard Tai reported a race condition in TBF, whenever SFQ perturb timer fires at the wrong time. The race is as follows: CPU 0 CPU 1 [1]: lock root [2]: qdisc_tree_flush_backlog() [3]: unlock root | | [5]: lock root | [6]: rehash | [7]: qdisc_tree_reduce_backlog() | [4]: qdisc_put() This can be abused to underflow a parent's qlen. Calling qdisc_purge_queue() instead of qdisc_tree_flush_backlog() should fix the race, because all packets will be purged from the qdisc before releasing the lock. Fixes: b05972f01e7d ("net: sched: tbf: don't call qdisc_put() while holding tree lock") Reported-by: Gerrard Tai <gerrard.tai@starlabs.sg> Suggested-by: Gerrard Tai <gerrard.tai@starlabs.sg> Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Zhengchao Shao <shaozhengchao@huawei.com> Link: https://patch.msgid.link/20250611111515.1983366-4-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
Gerrard Tai reported a race condition in TBF, whenever SFQ perturb timer
fires at the wrong time.

The race is as follows:

CPU 0                                 CPU 1
[1]: lock root
[2]: qdisc_tree_flush_backlog()
[3]: unlock root
 |
 |                                    [5]: lock root
 |                                    [6]: rehash
 |                                    [7]: qdisc_tree_reduce_backlog()
 |
[4]: qdisc_put()

This can be abused to underflow a parent's qlen.

Calling qdisc_purge_queue() instead of qdisc_tree_flush_backlog()
should fix the race, because all packets will be purged from the qdisc
before releasing the lock.

Fixes: b05972f01e7d ("net: sched: tbf: don't call qdisc_put() while holding tree lock")
Reported-by: Gerrard Tai <gerrard.tai@starlabs.sg>
Suggested-by: Gerrard Tai <gerrard.tai@starlabs.sg>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Zhengchao Shao <shaozhengchao@huawei.com>
Link: https://patch.msgid.link/20250611111515.1983366-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>