linux-stable.git/net/llc, branch linux-rolling-lts Linux kernel stable tree llc: fix SAP refcount leak when creating incoming sockets 2026-07-24T14:17:18+00:00 Xuanqiang Luo luoxuanqiang@kylinos.cn 2026-07-12T13:03:43+00:00 fd701fc0d065260ad2e5c2ff1c830afb73012590 commit 2c72eb6286347d05a885412fb076993bd5286b53 upstream. llc_sap_add_socket() takes a SAP reference for each socket added to a SAP, and llc_sap_remove_socket() releases it. llc_create_incoming_sock() takes an additional SAP reference after adding the child socket. This extra reference was balanced by an explicit llc_sap_put() in llc_ui_release() until commit 3100aa9d74db ("llc: fix SAP reference counting w.r.t. socket handling") removed that put. The corresponding hold in the accept path was left behind. When such a child socket is removed, only the reference taken by llc_sap_add_socket() is released. The extra reference keeps the SAP alive after its last socket is removed. Remove the obsolete hold. Fixes: 3100aa9d74db ("llc: fix SAP reference counting w.r.t. socket handling") Cc: stable@vger.kernel.org Signed-off-by: Xuanqiang Luo <luoxuanqiang@kylinos.cn> Link: https://patch.msgid.link/20260712130343.518797-1-xuanqiang.luo@linux.dev Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 2c72eb6286347d05a885412fb076993bd5286b53 upstream.

llc_sap_add_socket() takes a SAP reference for each socket added to a SAP,
and llc_sap_remove_socket() releases it. llc_create_incoming_sock() takes
an additional SAP reference after adding the child socket.

This extra reference was balanced by an explicit llc_sap_put() in
llc_ui_release() until commit 3100aa9d74db ("llc: fix SAP reference
counting w.r.t. socket handling") removed that put. The corresponding hold
in the accept path was left behind.

When such a child socket is removed, only the reference taken by
llc_sap_add_socket() is released. The extra reference keeps the SAP alive
after its last socket is removed. Remove the obsolete hold.

Fixes: 3100aa9d74db ("llc: fix SAP reference counting w.r.t. socket handling")
Cc: stable@vger.kernel.org
Signed-off-by: Xuanqiang Luo <luoxuanqiang@kylinos.cn>
Link: https://patch.msgid.link/20260712130343.518797-1-xuanqiang.luo@linux.dev
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
llc: fix SAP refcount leak in llc_ui_autobind() 2026-07-24T14:17:15+00:00 Shuangpeng Bai shuangpeng.kernel@gmail.com 2026-06-30T19:48:56+00:00 61a7ff4a62003b55a15022567486741b3bd83914 commit 660667cd406648bbaffbd5c0d897c2263a852f11 upstream. llc_ui_autobind() opens a SAP after choosing a dynamic LSAP. llc_sap_open() returns a reference owned by the caller, and llc_sap_add_socket() takes a second reference for the socket's membership in the SAP hash tables. llc_ui_bind() drops the caller's reference after adding the socket, but llc_ui_autobind() keeps it. When the socket is closed, llc_sap_remove_socket() releases only the socket reference, leaving the SAP on llc_sap_list with sk_count == 0. This is user-visible because repeated autobind and close cycles can consume all dynamic SAP values and make later autobinds fail with -EUSERS. Drop the caller's reference after a successful autobind, matching llc_ui_bind()'s ownership model. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Shuangpeng Bai <shuangpeng.kernel@gmail.com> Link: https://patch.msgid.link/20260630194856.1036497-1-shuangpeng.kernel@gmail.com Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 660667cd406648bbaffbd5c0d897c2263a852f11 upstream.

llc_ui_autobind() opens a SAP after choosing a dynamic LSAP.
llc_sap_open() returns a reference owned by the caller, and
llc_sap_add_socket() takes a second reference for the socket's
membership in the SAP hash tables.

llc_ui_bind() drops the caller's reference after adding the socket,
but llc_ui_autobind() keeps it. When the socket is closed,
llc_sap_remove_socket() releases only the socket reference, leaving
the SAP on llc_sap_list with sk_count == 0.

This is user-visible because repeated autobind and close cycles can consume
all dynamic SAP values and make later autobinds fail with -EUSERS.

Drop the caller's reference after a successful autobind, matching
llc_ui_bind()'s ownership model.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Shuangpeng Bai <shuangpeng.kernel@gmail.com>
Link: https://patch.msgid.link/20260630194856.1036497-1-shuangpeng.kernel@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net: make sk->sk_rcvtimeo lockless 2025-06-24T00:05:12+00:00 Eric Dumazet edumazet@google.com 2025-06-20T15:55:36+00:00 935b67675a9f233aa4ac4ae6452b2cc45418d839 Followup of commit 285975dd6742 ("net: annotate data-races around sk->sk_{rcv|snd}timeo"). Remove lock_sock()/release_sock() from ksmbd_tcp_rcv_timeout() and add READ_ONCE()/WRITE_ONCE() where it is needed. Also SO_RCVTIMEO_OLD and SO_RCVTIMEO_NEW can call sock_set_timeout() without holding the socket lock. Signed-off-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250620155536.335520-3-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
Followup of commit 285975dd6742 ("net: annotate data-races around
sk->sk_{rcv|snd}timeo").

Remove lock_sock()/release_sock() from ksmbd_tcp_rcv_timeout()
and add READ_ONCE()/WRITE_ONCE() where it is needed.

Also SO_RCVTIMEO_OLD and SO_RCVTIMEO_NEW can call sock_set_timeout()
without holding the socket lock.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250620155536.335520-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: remove sock_i_uid() 2025-06-24T00:04:03+00:00 Eric Dumazet edumazet@google.com 2025-06-20T13:30:01+00:00 c51da3f7a161c6822232be832abdffe47eb55b4c Difference between sock_i_uid() and sk_uid() is that after sock_orphan(), sock_i_uid() returns GLOBAL_ROOT_UID while sk_uid() returns the last cached sk->sk_uid value. None of sock_i_uid() callers care about this. Use sk_uid() which is much faster and inlined. Note that diag/dump users are calling sock_i_ino() and can not see the full benefit yet. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Lorenzo Colitti <lorenzo@google.com> Reviewed-by: Maciej Żenczykowski <maze@google.com> Link: https://patch.msgid.link/20250620133001.4090592-3-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
Difference between sock_i_uid() and sk_uid() is that
after sock_orphan(), sock_i_uid() returns GLOBAL_ROOT_UID
while sk_uid() returns the last cached sk->sk_uid value.

None of sock_i_uid() callers care about this.

Use sk_uid() which is much faster and inlined.

Note that diag/dump users are calling sock_i_ino() and
can not see the full benefit yet.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Lorenzo Colitti <lorenzo@google.com>
Reviewed-by: Maciej Żenczykowski <maze@google.com>
Link: https://patch.msgid.link/20250620133001.4090592-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
treewide, timers: Rename from_timer() to timer_container_of() 2025-06-08T07:07:37+00:00 Ingo Molnar mingo@kernel.org 2025-05-09T05:51:14+00:00 41cb08555c4164996d67c78b3bf1c658075b75f1 Move this API to the canonical timer_*() namespace. [ tglx: Redone against pre rc1 ] Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/all/aB2X0jCKQO56WdMt@gmail.com 
Move this API to the canonical timer_*() namespace.

[ tglx: Redone against pre rc1 ]

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/aB2X0jCKQO56WdMt@gmail.com
llc: fix data loss when reading from a socket in llc_ui_recvmsg() 2025-05-19T11:12:54+00:00 Ilia Gavrilov Ilia.Gavrilov@infotecs.ru 2025-05-15T12:20:15+00:00 239af1970bcb039a1551d2c438d113df0010c149 For SOCK_STREAM sockets, if user buffer size (len) is less than skb size (skb->len), the remaining data from skb will be lost after calling kfree_skb(). To fix this, move the statement for partial reading above skb deletion. Found by InfoTeCS on behalf of Linux Verification Center (linuxtesting.org) Fixes: 30a584d944fb ("[LLX]: SOCK_DGRAM interface fixes") Cc: stable@vger.kernel.org Signed-off-by: Ilia Gavrilov <Ilia.Gavrilov@infotecs.ru> Signed-off-by: David S. Miller <davem@davemloft.net> 
For SOCK_STREAM sockets, if user buffer size (len) is less
than skb size (skb->len), the remaining data from skb
will be lost after calling kfree_skb().

To fix this, move the statement for partial reading
above skb deletion.

Found by InfoTeCS on behalf of Linux Verification Center (linuxtesting.org)

Fixes: 30a584d944fb ("[LLX]: SOCK_DGRAM interface fixes")
Cc: stable@vger.kernel.org
Signed-off-by: Ilia Gavrilov <Ilia.Gavrilov@infotecs.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
treewide: Switch/rename to timer_delete[_sync]() 2025-04-05T08:30:12+00:00 Thomas Gleixner tglx@linutronix.de 2025-04-05T08:17:26+00:00 8fa7292fee5c5240402371ea89ab285ec856c916 timer_delete[_sync]() replaces del_timer[_sync](). Convert the whole tree over and remove the historical wrapper inlines. Conversion was done with coccinelle plus manual fixups where necessary. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> 
timer_delete[_sync]() replaces del_timer[_sync](). Convert the whole tree
over and remove the historical wrapper inlines.

Conversion was done with coccinelle plus manual fixups where necessary.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
llc: do not use skb_get() before dev_queue_xmit() 2025-03-03T14:00:04+00:00 Eric Dumazet edumazet@google.com 2025-02-27T08:26:42+00:00 64e6a754d33d31aa844b3ee66fb93ac84ca1565e syzbot is able to crash hosts [1], using llc and devices not supporting IFF_TX_SKB_SHARING. In this case, e1000 driver calls eth_skb_pad(), while the skb is shared. Simply replace skb_get() by skb_clone() in net/llc/llc_s_ac.c Note that e1000 driver might have an issue with pktgen, because it does not clear IFF_TX_SKB_SHARING, this is an orthogonal change. We need to audit other skb_get() uses in net/llc. [1] kernel BUG at net/core/skbuff.c:2178 ! Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI CPU: 0 UID: 0 PID: 16371 Comm: syz.2.2764 Not tainted 6.14.0-rc4-syzkaller-00052-gac9c34d1e45a #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 RIP: 0010:pskb_expand_head+0x6ce/0x1240 net/core/skbuff.c:2178 Call Trace: <TASK> __skb_pad+0x18a/0x610 net/core/skbuff.c:2466 __skb_put_padto include/linux/skbuff.h:3843 [inline] skb_put_padto include/linux/skbuff.h:3862 [inline] eth_skb_pad include/linux/etherdevice.h:656 [inline] e1000_xmit_frame+0x2d99/0x5800 drivers/net/ethernet/intel/e1000/e1000_main.c:3128 __netdev_start_xmit include/linux/netdevice.h:5151 [inline] netdev_start_xmit include/linux/netdevice.h:5160 [inline] xmit_one net/core/dev.c:3806 [inline] dev_hard_start_xmit+0x9a/0x7b0 net/core/dev.c:3822 sch_direct_xmit+0x1ae/0xc30 net/sched/sch_generic.c:343 __dev_xmit_skb net/core/dev.c:4045 [inline] __dev_queue_xmit+0x13d4/0x43e0 net/core/dev.c:4621 dev_queue_xmit include/linux/netdevice.h:3313 [inline] llc_sap_action_send_test_c+0x268/0x320 net/llc/llc_s_ac.c:144 llc_exec_sap_trans_actions net/llc/llc_sap.c:153 [inline] llc_sap_next_state net/llc/llc_sap.c:182 [inline] llc_sap_state_process+0x239/0x510 net/llc/llc_sap.c:209 llc_ui_sendmsg+0xd0d/0x14e0 net/llc/af_llc.c:993 sock_sendmsg_nosec net/socket.c:718 [inline] Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot+da65c993ae113742a25f@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/67c020c0.050a0220.222324.0011.GAE@google.com/T/#u Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Simon Horman <horms@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> 
syzbot is able to crash hosts [1], using llc and devices
not supporting IFF_TX_SKB_SHARING.

In this case, e1000 driver calls eth_skb_pad(), while
the skb is shared.

Simply replace skb_get() by skb_clone() in net/llc/llc_s_ac.c

Note that e1000 driver might have an issue with pktgen,
because it does not clear IFF_TX_SKB_SHARING, this is an
orthogonal change.

We need to audit other skb_get() uses in net/llc.

[1]

kernel BUG at net/core/skbuff.c:2178 !
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 16371 Comm: syz.2.2764 Not tainted 6.14.0-rc4-syzkaller-00052-gac9c34d1e45a #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
 RIP: 0010:pskb_expand_head+0x6ce/0x1240 net/core/skbuff.c:2178
Call Trace:
 <TASK>
  __skb_pad+0x18a/0x610 net/core/skbuff.c:2466
  __skb_put_padto include/linux/skbuff.h:3843 [inline]
  skb_put_padto include/linux/skbuff.h:3862 [inline]
  eth_skb_pad include/linux/etherdevice.h:656 [inline]
  e1000_xmit_frame+0x2d99/0x5800 drivers/net/ethernet/intel/e1000/e1000_main.c:3128
  __netdev_start_xmit include/linux/netdevice.h:5151 [inline]
  netdev_start_xmit include/linux/netdevice.h:5160 [inline]
  xmit_one net/core/dev.c:3806 [inline]
  dev_hard_start_xmit+0x9a/0x7b0 net/core/dev.c:3822
  sch_direct_xmit+0x1ae/0xc30 net/sched/sch_generic.c:343
  __dev_xmit_skb net/core/dev.c:4045 [inline]
  __dev_queue_xmit+0x13d4/0x43e0 net/core/dev.c:4621
  dev_queue_xmit include/linux/netdevice.h:3313 [inline]
  llc_sap_action_send_test_c+0x268/0x320 net/llc/llc_s_ac.c:144
  llc_exec_sap_trans_actions net/llc/llc_sap.c:153 [inline]
  llc_sap_next_state net/llc/llc_sap.c:182 [inline]
  llc_sap_state_process+0x239/0x510 net/llc/llc_sap.c:209
  llc_ui_sendmsg+0xd0d/0x14e0 net/llc/af_llc.c:993
  sock_sendmsg_nosec net/socket.c:718 [inline]

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: syzbot+da65c993ae113742a25f@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/67c020c0.050a0220.222324.0011.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
sysctl net: Remove macro checks for CONFIG_SYSCTL 2025-01-20T20:01:34+00:00 Denis Kirjanov kirjanov@gmail.com 2025-01-19T13:42:53+00:00 19d7750a06bb6063c8bcf2630766516215dc13dc Since dccp and llc makefiles already check sysctl code compilation with xxx-$(CONFIG_SYSCTL) we can drop the checks Signed-off-by: Denis Kirjanov <kirjanov@gmail.com> Link: https://patch.msgid.link/20250119134254.19250-1-kirjanov@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
Since dccp and llc makefiles already check sysctl code
compilation with xxx-$(CONFIG_SYSCTL)
we can drop the checks

Signed-off-by: Denis Kirjanov <kirjanov@gmail.com>
Link: https://patch.msgid.link/20250119134254.19250-1-kirjanov@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: llc: reset skb->transport_header 2024-12-27T19:23:37+00:00 Antonio Pastor antonio.pastor@gmail.com 2024-12-25T01:07:20+00:00 a024e377efed31ecfb39210bed562932321345b3 802.2+LLC+SNAP frames received by napi_complete_done with GRO and DSA have skb->transport_header set two bytes short, or pointing 2 bytes before network_header & skb->data. As snap_rcv expects transport_header to point to SNAP header (OID:PID) after LLC processing advances offset over LLC header (llc_rcv & llc_fixup_skb), code doesn't find a match and packet is dropped. Between napi_complete_done and snap_rcv, transport_header is not used until __netif_receive_skb_core, where originally it was being reset. Commit fda55eca5a33 ("net: introduce skb_transport_header_was_set()") only does so if not set, on the assumption the value was set correctly by GRO (and also on assumption that "network stacks usually reset the transport header anyway"). Afterwards it is moved forward by llc_fixup_skb. Locally generated traffic shows up at __netif_receive_skb_core with no transport_header set and is processed without issue. On a setup with GRO but no DSA, transport_header and network_header are both set to point to skb->data which is also correct. As issue is LLC specific, to avoid impacting non-LLC traffic, and to follow up on original assumption made on previous code change, llc_fixup_skb to reset the offset after skb pull. llc_fixup_skb assumes the LLC header is at skb->data, and by definition SNAP header immediately follows. Fixes: fda55eca5a33 ("net: introduce skb_transport_header_was_set()") Signed-off-by: Antonio Pastor <antonio.pastor@gmail.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20241225010723.2830290-1-antonio.pastor@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
802.2+LLC+SNAP frames received by napi_complete_done with GRO and DSA
have skb->transport_header set two bytes short, or pointing 2 bytes
before network_header & skb->data. As snap_rcv expects transport_header
to point to SNAP header (OID:PID) after LLC processing advances offset
over LLC header (llc_rcv & llc_fixup_skb), code doesn't find a match
and packet is dropped.

Between napi_complete_done and snap_rcv, transport_header is not used
until __netif_receive_skb_core, where originally it was being reset.
Commit fda55eca5a33 ("net: introduce skb_transport_header_was_set()")
only does so if not set, on the assumption the value was set correctly
by GRO (and also on assumption that "network stacks usually reset the
transport header anyway"). Afterwards it is moved forward by
llc_fixup_skb.

Locally generated traffic shows up at __netif_receive_skb_core with no
transport_header set and is processed without issue. On a setup with
GRO but no DSA, transport_header and network_header are both set to
point to skb->data which is also correct.

As issue is LLC specific, to avoid impacting non-LLC traffic, and to
follow up on original assumption made on previous code change,
llc_fixup_skb to reset the offset after skb pull. llc_fixup_skb
assumes the LLC header is at skb->data, and by definition SNAP header
immediately follows.

Fixes: fda55eca5a33 ("net: introduce skb_transport_header_was_set()")
Signed-off-by: Antonio Pastor <antonio.pastor@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20241225010723.2830290-1-antonio.pastor@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>