kernel/git/stable/linux-stable.git/net, branch linux-6.18.y

net/sched: fq: clamp quantum and initial_quantum in change path

2026-09-14T11:36:18+00:00

[ Upstream commit 094cc07f98dfe70a34e2a1923af17fd29b8cf622 ] The fq change path accepts TCA_FQ_QUANTUM in [1, INT_MAX] and TCA_FQ_INITIAL_QUANTUM up to INT_MAX, while fq_init() already clamps to [1, 1<<20]. A user can override the init clamp via tc qdisc change, restoring the small-quantum deficit spin that the init clamp prevents. Narrow iq_range.max to 1<<20 so TCA_FQ_INITIAL_QUANTUM is rejected at parse time. Clamp TCA_FQ_QUANTUM to [256, 1<<20] in fq_change() and fq_init() quantum to [256, 1<<20] for tiny-MTU devices. Conditions to recreate the bug: CONFIG_NET_SCH_FQ=y. Requires CAP_NET_ADMIN (namespace-local via unshare -Urn suffices). tc qdisc add dev dummy0 root fq tc qdisc change dev dummy0 root fq quantum 1 stab data 32768 size_log 15 cell_log 0 Fixes: 709f34f7c28d ("net/sched: fq: add overflow bounds to quantum and initial quantum") Reported-by: Vega Reviewed-by: Toke Høiland-Jørgensen Tested-by: Victor Nogueira Signed-off-by: Jamal Hadi Salim Link: https://patch.msgid.link/QDISC-0CFC.v3.20260901204856@mojatatu.com.2 Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

tcp: reject non zerocopy devmem tx

2026-09-14T11:36:18+00:00

[ Upstream commit 125755776bc6d4dd53eaf551c87e3d460625d638 ] Devmem tcp tx doesn't work without zero-copy, however it's not currently enforced if NETIF_F_SG isn't present. In this case, tcp_sendmsg_locked() will try the copy path and try to copy data from an iovec which consists of offsets into the dma-buf and would normally fail. Moreover, d9c56501c72fd ("net: tcp: block mixing readable and unreadable frags") relies on that and assumes that the devmem binding is present IFF we're using the zero-copy path, which can be used to mix net-iov and pages in a single skb, and break invariants. Let's reject devmem tx without zero-copy. Note, the parameter check the patch is modifying is too loose, we can create an io_uring request with dmabuf_id and all ZC flags, but which won't have the binding. We replace it with stricter validation. Fixes: bd61848900bff ("net: devmem: Implement TX path") Fixes: d9c56501c72fd ("net: tcp: block mixing readable and unreadable frags") Signed-off-by: Pavel Begunkov Reviewed-by: Mina Almasry Link: https://patch.msgid.link/fdc2478d8f21268d7078556409887d8e6ba0ad32.1788529053.git.asml.silence@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

ipmr: Call ipmr_fib_lookup() under RCU.

2026-09-14T11:36:18+00:00

[ Upstream commit 019c892e46544af0ae94ec833f79aa903c837666 ] Yi Lai reported RCU splat in reg_vif_xmit() below. [0] When CONFIG_IP_MROUTE_MULTIPLE_TABLES=n, ipmr_fib_lookup() uses rcu_dereference() without explicit rcu_read_lock(). Although rcu_read_lock_bh() is already held by the caller __dev_queue_xmit(), lockdep requires explicit rcu_read_lock() for rcu_dereference(). Let's move up rcu_read_lock() in reg_vif_xmit() to cover ipmr_fib_lookup(). [0]: WARNING: suspicious RCU usage 7.1.0-rc2-next-20260504-9d0d467c3572 #1 Not tainted ----------------------------- net/ipv4/ipmr.c:329 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 2 locks held by syz.2.17/1779: #0: ffffffff87896440 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #0: ffffffff87896440 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:891 [inline] #0: ffffffff87896440 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x239/0x4140 net/core/dev.c:4792 #1: ffff88801a199d18 (_xmit_PIMREG#2){+...}-{3:3}, at: spin_lock include/linux/spinlock.h:342 [inline] #1: ffff88801a199d18 (_xmit_PIMREG#2){+...}-{3:3}, at: __netif_tx_lock include/linux/netdevice.h:4795 [inline] #1: ffff88801a199d18 (_xmit_PIMREG#2){+...}-{3:3}, at: __dev_queue_xmit+0x1d5d/0x4140 net/core/dev.c:4865 stack backtrace: CPU: 1 UID: 0 PID: 1779 Comm: syz.2.17 Not tainted 7.1.0-rc2-next-20260504-9d0d467c3572 #1 PREEMPT(lazy) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x121/0x150 lib/dump_stack.c:120 dump_stack+0x19/0x20 lib/dump_stack.c:129 lockdep_rcu_suspicious+0x15b/0x1f0 kernel/locking/lockdep.c:6878 ipmr_fib_lookup net/ipv4/ipmr.c:329 [inline] reg_vif_xmit+0x2ee/0x3c0 net/ipv4/ipmr.c:540 __netdev_start_xmit include/linux/netdevice.h:5382 [inline] netdev_start_xmit include/linux/netdevice.h:5391 [inline] xmit_one net/core/dev.c:3889 [inline] dev_hard_start_xmit+0x170/0x700 net/core/dev.c:3905 __dev_queue_xmit+0x1df1/0x4140 net/core/dev.c:4871 dev_queue_xmit include/linux/netdevice.h:3423 [inline] packet_xmit+0x252/0x370 net/packet/af_packet.c:276 packet_snd net/packet/af_packet.c:3082 [inline] packet_sendmsg+0x39ad/0x5650 net/packet/af_packet.c:3114 sock_sendmsg_nosec net/socket.c:797 [inline] __sock_sendmsg net/socket.c:812 [inline] ____sys_sendmsg+0xa21/0xba0 net/socket.c:2716 ___sys_sendmsg+0x121/0x1c0 net/socket.c:2770 __sys_sendmsg+0x177/0x220 net/socket.c:2802 __do_sys_sendmsg net/socket.c:2807 [inline] __se_sys_sendmsg net/socket.c:2805 [inline] __x64_sys_sendmsg+0x80/0xc0 net/socket.c:2805 x64_sys_call+0x1d9c/0x21c0 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xc1/0x1020 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7f37e563ee5d Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 93 af 1b 00 f7 d8 64 89 01 48 RSP: 002b:00007ffe5caa7fa8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00000000005c5fa0 RCX: 00007f37e563ee5d RDX: 0000000000000000 RSI: 00002000000012c0 RDI: 0000000000000004 RBP: 00000000005c5fa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00000000005c5fac R15: 00000000005c5fa0 Fixes: b3b6babf4751 ("ipmr: Free mr_table after RCU grace period.") Reported-by: syzkaller Reported-by: Yi Lai Closes: https://lore.kernel.org/netdev/afrY34dLXNUboevf@ly-workstation/ Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260506065955.1695753-1-kuniyu@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

wifi: nl80211: fix UHR capability validation

2026-09-14T11:36:17+00:00

[ Upstream commit a140826caa2c14aa5a9a6990e514c5edbdb7eafd ] The ieee80211_uhr_capa_size_ok() function returns a boolean, but we need an error code here. Fix that. Fixes: 072e6f7f416f ("wifi: cfg80211: add initial UHR support") Cc: # no drivers with UHR yet Link: https://patch.msgid.link/20260303151614.e87ea9995be5.Ie164040a51855a3e548f05f0d0291d7d7993c7ee@changeid Signed-off-by: Johannes Berg Signed-off-by: Sasha Levin

net/sched: sch_htb: limit htb_classify inner-class filter hops

2026-09-14T11:36:15+00:00

[ Upstream commit 729c4896ab829169f95915d65edd530325910b37 ] htb_classify() follows each filter-selected inner class by switching to cl->filter_list, but never bounds the number of hops. A filter on an inner class can point back to itself or to another inner class that points back, creating an infinite loop in the packet classification path with the qdisc lock held and BH disabled — a soft lockup / panic from a single packet. Bound the traversal with a hop counter and drop the packet with a rate-limited warning once the bound is exceeded. The counter is incremented at the point the inner filter chain is picked up, after the TC_ACT_* switch has consumed the classifier verdict, so a terminal TC_ACT_QUEUED/STOLEN/TRAP on the last permitted chain still sets *qerr to __NET_XMIT_STOLEN and the packet is not charged as a drop by this qdisc or its parent. The bound is TC_HTB_MAXDEPTH, taken from HTB's own parameters rather than from the qdisc hierarchy depth limit. Class levels run from 0 to TC_HTB_MAXDEPTH - 1, so a traversal that strictly descends in level can take at most TC_HTB_MAXDEPTH hops. That descent is what a sane configuration does, but it is assumed here rather than enforced: htb_find() resolves a classid against every class in the qdisc, so a filter may equally select a sibling or an ancestor. The normal root -> inner -> leaf path takes a single hop, so the bound does not affect legitimate classification. htb_classify() can now return NULL irrespective of CONFIG_NET_CLS_ACT, whereas previously every NULL return sat inside that ifdef. The NULL handler in htb_enqueue() therefore cannot stay conditional either, so drop the ifdef around it. This matches hfsc_enqueue(), which has always handled a NULL class unconditionally. Without it, a kernel built without actions would dereference a NULL class instead of dropping. Conditions to recreate the bug: - CONFIG_NET_SCHED, CONFIG_NET_SCH_HTB, CONFIG_NET_CLS_U32, CONFIG_LOCKUP_DETECTOR. - Create an HTB qdisc on a device (e.g. lo), add an inner class 1:1 with a leaf child 1:10, install a root u32 filter selecting 1:1, and an inner-class u32 filter on 1:1 also selecting 1:1. - Send one packet (ping). On the unfixed kernel the classify loop spins with the qdisc lock held; with softlockup_panic=1 it panics. - Reachable from unprivileged user via unshare -Urn (CAP_NET_ADMIN). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Vega Co-developed-by: Victor Nogueira Signed-off-by: Victor Nogueira Signed-off-by: Jamal Hadi Salim Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260826143339.271935-1-victor@mojatatu.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

tcp: fix corruption of urgent data on multi-segment retransmit

2026-09-14T11:36:15+00:00

[ Upstream commit ce2b807f42ed5e55567b8864ab72963f90779270 ] On the normal xmit path, while in urgent mode we refuse to build a multi-segment TSO packet, so every segment gets its own urg_ptr: /* tcp_write_xmit() */ limit = mss_now; if (tso_segs > 1 && !tcp_urg_mode(tp)) limit = tcp_mss_split_point(...); The retransmit path has no such guard. __tcp_retransmit_skb() builds a segs > 1 skb and hands it to the GSO layer, which only advances th->seq per segment and copies urg_ptr verbatim: /* __tcp_retransmit_skb() */ len = cur_mss * segs; /* segs > 1, no urg_mode check */ ... /* tcp_gso_segment(): bumps seq only, urg_ptr is copied */ urg_ptr is an offset from the segment's own seq, so a copied value points at a different place on each segment. The receiver rebuilds the absolute urgent seq as seg.seq + urg_ptr, so it walks a moving urgent point instead of the one OOB byte: seg1 seq 1 urg_ptr 5001 -> urgent @ 5001 (ok) seg2 seq 1001 urg_ptr 5001 -> urgent @ 6001 (wrong, +MSS) seg3 seq 2001 urg_ptr 5001 -> urgent @ 7001 (wrong, +2*MSS) The real OOB byte is never pointed at, so the receiver stops splicing it out and delivers it as normal in-band data, corrupting the stream. Guard the retransmit length like the xmit path: keep segs = 1 while in urgent mode. Fixes: 10d3be569243 ("tcp-tso: do not split TSO packets at retransmit time") Signed-off-by: Jiayuan Chen Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260826141145.67823-1-jiayuan.chen@linux.dev Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net/sched: bound qdisc_pkt_len to prevent qdisc soft lockup

2026-09-14T11:36:15+00:00

[ Upstream commit 8f735d64382dcf162f4276d6699d03ad2f859c0b ] qdisc_get_stab() accepts a user-supplied size table, and __qdisc_calculate_pkt_len() amplifies qdisc_pkt_len() through the overhead, the size-table data (u16), and size_log (up to STAB_SIZE_LOG_MAX). A crafted stab can therefore set qdisc_pkt_len() to ~1 GiB for an ordinary skb. Per-flow deficit schedulers such as DRR and ETS replenish one quantum per loop iteration; with a tiny quantum (1) they spin billions of times under the qdisc lock, producing a soft lockup / RCU stall as illustrated by vega@nebusec.ai. Cap the final qdisc_pkt_len() to QDISC_PKT_LEN_MAX so the size-table amplification cannot drive deficit schedulers into an unbounded loop. A legitimate size table (e.g. qfq's overhead 999999999, which is handled by dropping) is still accepted. Introduce cap QDISC_PKT_LEN_MAX (1 << 20) = 1 MiB which is well above any legitimate single-skb wire length: the largest current skb->len is GSO_MAX_SIZE (524280), and an ATM-style size table (53/48 cell tax) amplifies that to ~578 KB, both comfortably below 1 MiB. At the same time, 1 MiB bounds the deficit refill loop to ~1M iterations per packet with quantum=1, which completes in a few milliseconds well under the demonstrated softlockup threshold (~10^9 iterations). Conditions to recreate the bug: - CONFIG_NET_SCHED=y, CONFIG_NET_SCH_DRR=y (or CONFIG_NET_SCH_ETS=y). - Attach a DRR (or ETS) root qdisc with a crafted TCA_STAB that amplifies qdisc_pkt_len to ~1 GiB (e.g. size_log=15, data=[32768]). - Add a class with a tiny quantum of 1 and send one small packet; the deficit loop spins billions of times under the qdisc lock and trips the softlockup detector (panic with kernel.softlockup_panic=1). - Reachable as root or from an unprivileged user in a fresh user+net namespace (unshare -Urn) with namespace-local CAP_NET_ADMIN. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: vega@nebusec.ai Tested-by: Victor Nogueira Signed-off-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260825081403.133992-1-jhs@mojatatu.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

netfilter: x_tables: replace pr_{info,err}() by pr_info_ratelimited()

2026-09-14T11:36:14+00:00

[ Upstream commit 793d9eda4821f75b5f7cc9e6a870b72a58b44c2b ] Several xtables extension still use pr_err() or pr_info() without ratelimit. For xt_cgroup, while at this, remove redundant "xt_cgroup:" prefix since pr_fmt is already set on. Fixes: c38c4597e4bf ("netfilter: implement xt_cgroup cgroup2 path match") Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: xt_HL: add pr_fmt and checkentry validation

2026-09-14T11:36:14+00:00

[ Upstream commit 24bd5c2679caf8a228d90cafa221da4b47fd6642 ] Add pr_fmt to prefix log messages with the module name for easier debugging in dmesg. Add checkentry functions for IPv4 (ttl_mt_check) and IPv6 (hl_mt6_check) to validate the match mode at rule registration time, rejecting invalid modes with -EINVAL. The evaluation function returns false in case the mode is unknown, so this is a cleanup, not a bug fix. Signed-off-by: Marino Dzalto Signed-off-by: Florian Westphal Stable-dep-of: 793d9eda4821 ("netfilter: x_tables: replace pr_{info,err}() by pr_info_ratelimited()") Signed-off-by: Sasha Levin

netfilter: nf_tables: move hardware offload step after building the chain blob

2026-09-14T11:36:14+00:00

[ Upstream commit b1881d362e1924b66f6016c3efd28807032b41bf ] Allocate the chain blob before the ruleset offload to reduce chances of entering an inconsistent state where the offloaded ruleset in the nic and the software ruleset differ. Fixes: c9626a2cbdb2 ("netfilter: nf_tables: add hardware offload support") Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin