kernel/linux.git/net/ipv4, branch v7.0.13

netfilter: nft_fib: fix stale stack leak via the OIFNAME register

2026-06-19T11:48:12+00:00

[ Upstream commit ab185e0c4fb82dfba6fb86f8271e06f931d9c64c ] For NFT_FIB_RESULT_OIFNAME the destination register is declared with len = IFNAMSIZ (four 32-bit registers), but on the lookup-fail, RTN_LOCAL and oif-mismatch paths nft_fib{4,6}_eval() only writes one register via "*dest = 0". The remaining three registers are left as whatever was on the stack in nft_do_chain()'s struct nft_regs, and a downstream expression that loads the register span can leak that uninitialised kernel stack to userspace. The NFTA_FIB_F_PRESENT existence check has the same shape: it is only meaningful for NFT_FIB_RESULT_OIF, yet it was accepted for any result type while the eval stores a single byte via nft_reg_store8(), leaving the rest of the declared span stale. Fix both: - replace the bare "*dest = 0" in the eval with nft_fib_store_result(), which strscpy_pad()s the whole IFNAMSIZ for OIFNAME (and is already used on the other early-return path), and - restrict NFTA_FIB_F_PRESENT to NFT_FIB_RESULT_OIF and declare its destination as a single u8, so the marked span matches the one byte the eval writes. Fixes: f6d0cbcf09c5 ("netfilter: nf_tables: add fib expression") Suggested-by: Florian Westphal Cc: stable@vger.kernel.org Signed-off-by: Davide Ornaghi Signed-off-by: Pablo Neira Ayuso [ kept the tree's older `ip6_route_lookup()`/`rt6_info` IPv6 context and changed only `*dest = 0;` to `nft_fib_store_result(dest, priv, NULL);` ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

inet: frags: fix use-after-free caused by the fqdir_pre_exit() flush

2026-06-19T11:48:03+00:00

commit 32594b09854970d7ba83eb2dc8c69a2edd158c8e upstream. On netns teardown, fqdir_pre_exit() walks the fqdir rhashtable and flushes every fragment queue that is not yet complete using inet_frag_queue_flush(). That helper frees all the skbs queued on the fragment queue but does not set INET_FRAG_COMPLETE, and leaves q->fragments_tail and q->last_run_head pointing at the freed skbs. The queue itself stays in the rhashtable. fqdir_pre_exit() first lowers high_thresh to 0 to stop new queue lookups, but it cannot stop a fragment that already obtained the queue through inet_frag_find() earlier and stalled just before taking the queue lock. Once that fragment resumes after the flush and takes the queue lock, it passes the INET_FRAG_COMPLETE check and then dereferences the freed fragments_tail. inet_frag_queue_insert() reads FRAG_CB() and ->len of that pointer and, on the append path, writes ->next_frag, causing a slab use-after-free. IPv6, nf_conntrack_reasm6 and 6lowpan reassembly share the same flush path and are affected as well. Reset rb_fragments, fragments_tail and last_run_head in inet_frag_queue_flush() so a flushed queue no longer points at the freed skbs. A fragment that resumes after the flush and takes the queue lock then finds an empty queue and starts a new run instead of dereferencing the freed fragments_tail. ip_frag_reinit() already performed this reset after its own flush, so drop the now duplicate code there. Cc: stable@vger.kernel.org Fixes: 006a5035b495 ("inet: frags: flush pending skbs in fqdir_pre_exit()") Suggested-by: Eric Dumazet Signed-off-by: Hyunwoo Kim Link: https://patch.msgid.link/ah6ukYq5G98LshdA@v4bel Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

udp: clear skb->dev before running a sockmap verdict

2026-06-19T11:48:00+00:00

commit 3c94f241f776562c489876ff506f366224565c21 upstream. On the UDP receive path skb->dev is repurposed as dev_scratch (the truesize/state cache set by udp_set_dev_scratch()), through the union { struct net_device *dev; unsigned long dev_scratch; } in sk_buff. When a UDP socket is in a sockmap, sk_data_ready is sk_psock_verdict_data_ready(), which calls udp_read_skb() -> recv_actor() (sk_psock_verdict_recv) to run the attached SK_SKB verdict program in softirq. If that program calls a socket-lookup helper (bpf_sk_lookup_tcp/udp, bpf_skc_lookup_tcp), bpf_skc_lookup() does: if (skb->dev) caller_net = dev_net(skb->dev); skb->dev still holds the dev_scratch value (a non-NULL integer), so dev_net() dereferences it as a struct net_device * and the kernel takes a general protection fault on a non-canonical address in softirq: Oops: general protection fault, probably for non-canonical address 0x1010000800004a0 CPU: 1 UID: 0 PID: 1406 Comm: syz.2.19 Not tainted 7.1.0-rc6 #1 PREEMPT(full) RIP: 0010:bpf_skc_lookup net/core/filter.c:7033 [inline] RIP: 0010:bpf_sk_lookup+0x45/0x160 net/core/filter.c:7047 Call Trace: bpf_prog_4675cb904b7071f8+0x12e/0x14e bpf_prog_run_pin_on_cpu+0xc6/0x1f0 sk_psock_verdict_recv+0x1ba/0x350 udp_read_skb+0x31a/0x370 sk_psock_verdict_data_ready+0x2e3/0x600 __udp_enqueue_schedule_skb+0x4c8/0x650 udpv6_queue_rcv_one_skb+0x3ec/0x740 udp6_unicast_rcv_skb+0x11d/0x140 ip6_protocol_deliver_rcu+0x61e/0x950 ip6_input_finish+0xa9/0x150 NF_HOOK+0x286/0x2f0 ip6_input+0x117/0x220 NF_HOOK+0x286/0x2f0 __netif_receive_skb+0x85/0x200 process_backlog+0x374/0x9a0 __napi_poll+0x4f/0x1c0 net_rx_action+0x3b0/0x770 handle_softirqs+0x15a/0x460 do_softirq+0x57/0x80 The rmem charge that dev_scratch accounted for is released by skb_recv_udp() on dequeue, just above, so the scratch is dead by the time recv_actor() runs. Clear skb->dev so bpf_skc_lookup() falls back to sock_net(skb->sk), which skb_set_owner_sk_safe() set just above. Fixes: 965b57b469a5 ("net: Introduce a new proto_ops ->read_skb()") Cc: stable@vger.kernel.org Signed-off-by: Sechang Lim Reviewed-by: Jiayuan Chen Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260603162737.697215-1-rhkrqnwk98@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

netfilter: x_tables: avoid leaking percpu counter pointers

2026-06-19T11:47:53+00:00

[ Upstream commit f7f2fbb0e893a0238dc464f8d8c0f5609bec584f ] The native and compat get-entries paths copy the fixed rule entry header from the kernelized rule blob to userspace before overwriting the entry's counter fields with a sanitized counter snapshot. On SMP kernels, entry->counters.pcnt contains the percpu allocation address used by x_tables rule counters. A caller can provide a userspace buffer that faults during the initial fixed-header copy after pcnt has been copied but before the later sanitized counter copy runs. The syscall then returns -EFAULT while leaving the raw percpu pointer in userspace. Copy only the fixed entry prefix before counters from the kernelized rule blob, then copy the sanitized counter snapshot into the counter field. Apply this ordering to the IPv4, IPv6, and ARP native and compat get-entries implementations so a fault cannot expose the internal percpu counter pointer. Fixes: 71ae0dff02d7 ("netfilter: xtables: use percpu rule counters") Signed-off-by: Kyle Zeng Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: nf_conntrack: destroy stale expectfn expectations on unregister

2026-06-19T11:47:53+00:00

[ Upstream commit c3009418f9fa1dcb3eb86f4d8c92583537b5faa3 ] NAT helpers such as nf_nat_h323 store a raw pointer to module text in exp->expectfn (e.g. ip_nat_q931_expect). nf_ct_helper_expectfn_unregister() only unlinks the callback descriptor and never walks the expectation table, so an expectation pending at module removal survives with a dangling exp->expectfn into freed module text. When the expected connection arrives, init_conntrack() invokes exp->expectfn(), now a stale pointer into the unloaded module. Reproduced on a KASAN build by loading the H.323 helpers, creating a Q.931 expectation, unloading nf_nat_h323, then connecting to the expected port: Oops: int3: 0000 [#1] SMP KASAN NOPTI RIP: 0010:0xffffffffa06102d1 init_conntrack.isra.0 (net/netfilter/nf_conntrack_core.c:1862) nf_conntrack_in (net/netfilter/nf_conntrack_core.c:2049) ipv4_conntrack_local (net/netfilter/nf_conntrack_proto.c:223) nf_hook_slow (net/netfilter/core.c:619) __ip_local_out (net/ipv4/ip_output.c:120) __tcp_transmit_skb (net/ipv4/tcp_output.c:1715) tcp_connect (net/ipv4/tcp_output.c:4374) tcp_v4_connect (net/ipv4/tcp_ipv4.c:345) __sys_connect (net/socket.c:2167) Modules linked in: nf_conntrack_h323 [last unloaded: nf_nat_h323] Reaching the dangling state requires CAP_SYS_MODULE in the initial user namespace to remove a NAT helper that still has live expectations, so this is a robustness fix; leaving an expectation pointing at freed text is wrong regardless. Add nf_ct_helper_expectfn_destroy(), which walks the expectation table and drops every expectation whose ->expectfn matches the descriptor being torn down. Call it from each NAT helper's exit path after the existing RCU grace period, so no expectation outlives the code it points at and no extra synchronize_rcu() is introduced. With the fix, the same reproducer runs to completion without the Oops. Fixes: f587de0e2feb ("[NETFILTER]: nf_conntrack/nf_nat: add H.323 helper port") Reported-by: Xiang Mei Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Weiming Shi Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

esp: fix page frag reference leak on skb_to_sgvec failure

2026-06-19T11:47:52+00:00

[ Upstream commit 2982e599fff6faa21c8df147d96fc7af6c1a2f24 ] In esp_output_tail(), when esp->inplace is false, the old skb page frags are replaced with a new page from the xfrm page_frag cache. The source scatterlist (sg) is built from the old frags before the replacement, and esp_ssg_unref() is responsible for releasing the old page references after the crypto operation completes. However, if the second skb_to_sgvec() call (which builds the destination scatterlist from the new page) fails, the code jumps to error_free which only calls kfree(tmp). The old page frag references captured in the source scatterlist are never released: 1. sg[] is built from old frags via skb_to_sgvec() (no extra get_page) 2. nr_frags is set to 1 and frag[0] is replaced with the new page 3. Second skb_to_sgvec() fails -> goto error_free 4. kfree(tmp) frees the sg[] memory but old frags are not unref'd 5. kfree_skb() only releases frag[0] (the new page), not the old ones Fix this by adding a bool parameter to esp_ssg_unref() that, when true, unconditionally unrefs the source scatterlist frags without checking req->src and req->dst, since those fields are not yet initialized by aead_request_set_crypt() at the point of the error. Existing callers pass false to preserve the original behavior. The same issue exists in both esp4 and esp6 as the code is identical. Fixes: cac2661c53f3 ("esp4: Avoid skb_cow_data whenever possible") Fixes: 03e2a30f6a27 ("esp6: Avoid skb_cow_data whenever possible") Signed-off-by: Alessandro Schino <7991aleschino@gmail.com> Signed-off-by: Steffen Klassert Stable-dep-of: 26aad08a9289 ("esp: fix page frag reference leak on skb_to_sgvec failure") Signed-off-by: Sasha Levin

ipv4: restrict IPOPT_SSRR and IPOPT_LSRR options

2026-06-19T11:47:46+00:00

[ Upstream commit d3915a1f5a4bc0ac911032903c3c6ab8df9fcc7c ] This patch restricts setting Loose Source and Record Route (LSRR) and Strict Source and Record Route (SSRR) IP options to users with CAP_NET_RAW capability. This prevents unprivileged applications from forcing packets to route through attacker-controlled nodes to leak TCP ISN and possibly other protocol information. While LSRR and SSRR are commonly filtered in many network environments, they may still be supported and forwarded along some network paths. RFC 7126 (Recommendations on Filtering of IPv4 Packets Containing IPv4 Options) recommend to drop these options in 4.3 and 4.4. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Tamir Shahar Reported-by: Amit Klein Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260602161547.2642155-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

tcp: Add preempt_{disable,enable}_nested() in reqsk_queue_hash_req().

2026-06-19T11:47:44+00:00

[ Upstream commit e10902df24488ca722303133acfc82490f7d59ad ] syzbot reported a weird reqsk->rsk_refcnt underflow in __inet_csk_reqsk_queue_drop(). The captured reqsk_put() in __inet_csk_reqsk_queue_drop() is called only when it successfully removes reqsk from ehash. Moreover, reqsk_timer_handler() calls another reqsk_put() after that. This indicates that the reqsk was missing both refcnts for ehash and the timer itself. Since all the syzbot reports had PREEMPT_RT enabled, the only possible scenario is that reqsk_queue_hash_req() is preempted after mod_timer() and before refcount_set(), and then the timer triggered after 1s aborts the reqsk due to its listener's close(). Let's wrap mod_timer() and refcount_set() with preempt_disable_nested() and preempt_enable_nested(). Note that inet_ehash_insert() holds the normal spin_lock() (mutex in PREEMPT_RT), so it must be called outside of preempt_disable_nested(), but this is fine. The lookup path just ignores 0 sk_refcnt entries in ehash and tries to create another reqsk, but this will fail at inet_ehash_insert(). [0]: refcount_t: underflow; use-after-free. WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28, CPU#0: ktimers/0/16 Modules linked in: CPU: 0 UID: 0 PID: 16 Comm: ktimers/0 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 RIP: 0010:refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28 Code: e4 7d d1 0a 67 48 0f b9 3a eb 4a e8 38 3d 23 fd 48 8d 3d e1 7d d1 0a 67 48 0f b9 3a eb 37 e8 25 3d 23 fd 48 8d 3d de 7d d1 0a <67> 48 0f b9 3a eb 24 e8 12 3d 23 fd 48 8d 3d db 7d d1 0a 67 48 0f RSP: 0000:ffffc90000157948 EFLAGS: 00010246 RAX: ffffffff84a1301b RBX: 0000000000000003 RCX: ffff88801ca98000 RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffffffff8f72ae00 RBP: ffffffff99ae3b01 R08: ffff88801ca98000 R09: 0000000000000005 R10: 0000000000000100 R11: 0000000000000004 R12: ffff8880425ef568 R13: ffff8880425ef4f8 R14: ffff8880425ef578 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888126386000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7b46710e9c CR3: 000000000dbb6000 CR4: 00000000003526f0 Call Trace: __refcount_sub_and_test include/linux/refcount.h:400 [inline] __refcount_dec_and_test include/linux/refcount.h:432 [inline] refcount_dec_and_test include/linux/refcount.h:450 [inline] reqsk_put include/net/request_sock.h:136 [inline] __inet_csk_reqsk_queue_drop+0x3ce/0x440 net/ipv4/inet_connection_sock.c:1007 reqsk_timer_handler+0x651/0xdf0 net/ipv4/inet_connection_sock.c:1137 call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748 expire_timers kernel/time/timer.c:1799 [inline] __run_timers kernel/time/timer.c:2374 [inline] __run_timer_base+0x6a3/0x9f0 kernel/time/timer.c:2386 run_timer_base kernel/time/timer.c:2395 [inline] run_timer_softirq+0x67/0x170 kernel/time/timer.c:2403 handle_softirqs+0x1de/0x6d0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] run_ktimerd+0x69/0x100 kernel/softirq.c:1151 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Fixes: d2d6422f8bd1 ("x86: Allow to enable PREEMPT_RT.") Reported-by: syzbot+e809069bc15f26300526@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/6a1a7bcf.0a9e871e.332604.000b.GAE@google.com/ Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Reviewed-by: Sebastian Andrzej Siewior Link: https://patch.msgid.link/20260601182101.3183993-1-kuniyu@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

xfrm: esp: restore combined single-frag length gate

2026-06-09T10:32:40+00:00

commit dfa0d7b0ff1eb6b2c416b8fdb9b4f2cefba57a40 upstream. The ESP out-of-place fast path appends the trailer in esp_output_head() before esp_output_tail() allocates the destination page frag. The head-side gate currently checks skb->data_len and tailen separately, but the tail code allocates a single destination frag from the combined post-trailer skb->data_len. Reject the page-frag fast path when the combined aligned length exceeds a page. Otherwise skb_page_frag_refill() may fall back to a single page while the destination sg still spans the combined skb->data_len. Restore this combined-length page gate for both IPv4 and IPv6. Fixes: 5bd8baab087d ("esp: limit skb_page_frag_refill use to a single page") Cc: stable@vger.kernel.org Signed-off-by: Lin Ma Signed-off-by: Chenyuan Mi Signed-off-by: Jingguo Tan Reviewed-by: Sabrina Dubroca Signed-off-by: Steffen Klassert Signed-off-by: Greg Kroah-Hartman

xfrm: ah: use skb_to_full_sk in async output callbacks

2026-06-09T10:32:40+00:00

commit 79d8be262377f7112cfa3088dfc4142d5a2533f3 upstream. When AH output is offloaded to an asynchronous crypto provider (hardware accelerators such as AMD CCP, or a forced-async software shim used for testing), the digest completion fires ah_output_done() / ah6_output_done() on a workqueue. The egress skb at that point may have been originated by a TCP listener sending a SYN-ACK, which sets skb->sk to a request_sock via skb_set_owner_edemux(); it may also have been originated by an inet_timewait_sock retransmit. Neither is a full struct sock, and passing the raw skb->sk to xfrm_output_resume() then forwards a non-full socket through the rest of the xfrm output chain. xfrm_output_resume() and its downstream consumers expect a full sk where they dereference at all. The natural egress path through ah_output_done() does not crash today because the consumers that read past sock_common are either gated by sk_fullsock() or short-circuit on flags that are clear on a fresh request_sock; an exhaustive walk of the 50 most plausible consumers under sch_fq, dev_queue_xmit, netfilter, tc-egress and cgroup-egress BPF found no current unguarded deref. The bug is still a real type confusion that future consumer changes could turn into a memory-corruption primitive. This is the same bug class fixed for ESP in commit 1620c88887b1 ("xfrm: Fix the usage of skb->sk"). Apply the analogous fix to AH: convert skb->sk to a full socket pointer (or NULL) via skb_to_full_sk() before handing it to xfrm_output_resume(). The same async AH callbacks were touched recently for an independent ESN-related ICV layout bug in commit ec54093e6a8f ("xfrm: ah: account for ESN high bits in async callbacks"); the sk type-confusion addressed here is orthogonal. This patch is part of an ongoing audit of the AH callback paths; an ah_output ihl-validation hardening series is also currently under review on netdev. Reproduced under UML + KASAN + lockdep with a forced-async hmac(sha1) shim that registers at priority 9999 and wraps the sync in-tree hmac-sha1-lib. With the shim loaded, ah_output_done runs on every SYN-ACK egress through a transport-mode AH SA and skb->sk arrives as a request_sock (TCP_NEW_SYN_RECV); after this patch, xfrm_output_resume() receives the listener (the result of sk_to_full_sk()) and consumer derefs land on full-sock fields as intended. Fixes: 9ab1265d5231 ("xfrm: Use actual socket sk instead of skb socket for xfrm_output_resume") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Michael Bommarito Signed-off-by: Steffen Klassert Signed-off-by: Greg Kroah-Hartman