Vulnerabilidades do Linux Linux

In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_cake: drop WARN_ON(1) for malformed packets in ACK filter The sch_cake ACK filter parses packets to find the TCP header and filter duplicated ACKs if the flow is backlogged. The parsing code contains a WARN_ON(1) which can be triggered by a malformed IP header in certain cases. Depending on the system configuration, this leads either to either spamming dmesg with warnings, or a panic if panic_on_warn is set. The code already correctly skips the offending packet in the branch that triggers the warning, so the WARN_ON itself doesn't really serve any purpose. So just drop it altogether to avoid the inconvenient side effects.

In the Linux kernel, the following vulnerability has been resolved: vhost-scsi: Validate T10 PI scatterlist counts When T10 PI is negotiated, vhost-scsi splits protection bytes from the data iterator before mapping the request scatterlists. A malformed request can claim protection bytes that cover or exceed the full payload length. The former leaves no data bytes to map, while the latter underflows exp_data_len before advancing the iterator. Both cases can let a zero data SGL count reach sg_alloc_table_chained(), which triggers BUG_ON(!nents). Reject protection lengths that cover or exceed the payload before subtracting prot_bytes and advancing the iterator. Also propagate negative errors from the protection SGL calculation before calling the allocator, matching the data SGL path.

In the Linux kernel, the following vulnerability has been resolved: vhost-scsi: reject feature changes after endpoint vhost_scsi_setup_vq_cmds() runs from VHOST_SCSI_SET_ENDPOINT and allocates each command's protection scatterlist array (prot_sgl) according to the acknowledged VIRTIO_SCSI_F_T10_PI bit. The command pools are not rebuilt when VHOST_SET_FEATURES changes that bit later. Although virtio feature bits must not change after feature negotiation, vhost_scsi_set_features() currently accepts such a request after the endpoint is active and updates acked_features. Enabling T10-PI after endpoint setup therefore leaves prot_sgl NULL while the I/O path follows the new feature bit. For a 129-page protection payload, vhost_scsi_mapal() passes the missing first chunk to sg_alloc_table_chained(): sg_alloc_table_chained(table, 129, first_chunk=NULL, nents_first_chunk=inline_sg_cnt) sg_pool_index() then hits: BUG_ON(nents > SG_CHUNK_SIZE); /* 129 > 128 */ The kernel reported the following call trace and register state: Call Trace: <TASK> ? __sg_alloc_table+0x1d8/0x250 ? __pfx_vhost_run_work_list+0x10/0x10 [vhost] sg_alloc_table_chained+0x59/0xf0 ? __pfx_sg_pool_alloc+0x10/0x10 ? vhost_scsi_calc_sgls.constprop.0+0x43/0x60 [vhost_scsi] vhost_scsi_handle_vq+0xf02/0x1700 [vhost_scsi] ? __pfx_vhost_scsi_handle_vq+0x10/0x10 [vhost_scsi] vhost_scsi_handle_kick+0x37/0x50 [vhost_scsi] vhost_run_work_list+0x8e/0xd0 [vhost] vhost_task_fn+0xe1/0x210 ret_from_fork+0x348/0x540 </TASK> RIP: 0010:0x4 CR2 = 0x4 RSP: 0018:ffffc90000dbf940 EFLAGS: 00010202 RAX: ffffffff82396810 RBX: ffff88811dc28b80 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000820 RDI: 0000000000000081 VHOST_F_LOG_ALL is a vhost-specific runtime feature and remains the only exception. Reject changes to any feature other than VHOST_F_LOG_ALL while the endpoint is active. This preserves the existing runtime log toggle while preventing feature-dependent command resources and data-path state from becoming inconsistent. Userspace must clear the endpoint before changing any other negotiated feature and set the endpoint up again afterward.

In the Linux kernel, the following vulnerability has been resolved: net/openvswitch: check Ethernet header length in key_extract() When a packet arrives on an ARPHRD_NONE device (e.g. TUN), ovs_flow_key_extract() trusts the user-provided skb->protocol field: if it is ETH_P_TEB, the packet is classified as MAC_PROTO_ETHERNET and key_extract() is called without ensuring the skb has ETH_HLEN (14) bytes of linear data. key_extract() unconditionally pulls 2 * ETH_ALEN bytes for MAC addresses and parse_ethertype() pulls 2 more, either of which triggers a kernel BUG in __skb_pull() when the linear area is too small. kernel BUG at include/linux/skbuff.h:2848! RIP: 0010:key_extract+0xa7e/0xd90 net/openvswitch/flow.c:933 ovs_flow_key_extract+0x419/0xa70 ovs_vport_receive+0x222/0x390 netdev_frame_hook+0x3e0/0x630 tun_get_user+0x2d0c/0x38e0 Fixed by calling check_header() in key_extract() before accessing the Ethernet header.

In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_api: Always acquire rtnl_lock when destroying locked classifiers Another challenge with unlocked filters. There is a short window in tc_new_tfilter where a tcf_proto can be found and briefly referenced by a totally unrelated, unlocked classifier's request and cause a race. Feng created a poc which created this race with two threads, one creating a u32 filter and other a flower filter in the same chain/prio: 1. Both threads enter tc_new_tfilter, both find the chain empty, both drop filter_chain_lock 2. u32 finishes tcf_proto_create("u32") first, calls tcf_chain_tp_insert_unique() -> inserts u32_tp into the chain 3. flower finishes tcf_proto_create("flower") later, calls tcf_chain_tp_insert_unique() -> tcf_chain_tp_find() now sees u32_tp already there, takes a reference on it, destroys flower's own tp_new and returns u32_tp to the caller. Flower then hits the kind mismatch check (because it requested for kind "flower" but tp->ops->kind is "u32") and goes through the errout path which calls tcf_proto_put() on u32_tp. If the u32 thread has already gone through its own errout (its change() call failed on the PoC's empty options) and dropped its create and insert refs, flower's put is the last one and drops u32_tp's refcnt to zero. At this point tp->ops->destroy() runs in a context that never took rtnl_lock. When that happens, it might cause a UAF like the following (illustrated by the PoC): [ +0.000710] BUG: KASAN: slab-use-after-free in u32_init (net/sched/cls_u32.c:393) [ +0.000281] Read of size 8 at addr ffff888120022f00 by task poc_feng_xue/524 Call Trace: u32_init (net/sched/cls_u32.c:393) tc_new_tfilter (net/sched/cls_api.c:2378) Allocated by task 526: u32_init (net/sched/cls_u32.c:378) tc_new_tfilter (net/sched/cls_api.c:2378) Freed by task 522: kfree u32_destroy (net/sched/cls_u32.c:662) tcf_proto_destroy (net/sched/cls_api.c:446) tcf_proto_put (net/sched/cls_api.c:459) tc_new_tfilter (net/sched/cls_api.c:2459) Fix this by having tcf_proto_destroy() take rtnl_lock around tp->ops->destroy() for locked classifiers whenever rtnl is not held. To explain why I used a temp variable "not_lockless" I'd like to point to a semi-related note on rtnl_held vs TCF_PROTO_OPS_DOIT_UNLOCKED (adding here for future cleanup if deemed necessary): The rtnl_held parameter and the TCF_PROTO_OPS_DOIT_UNLOCKED flag are redundant sources of truth for whether rtnl_lock is held. Among the nine classifier destroy(..rtnl_held..) callbacks, only flower consults the rtnl_held parameter which it propagates to tc_setup_cb_destroy() and tc_setup_cb_call(). The other eight (u32, flow, bpf, cgroup, route, basic, fw, mall) ignore it entirely;-> those that call tc_setup_cb_destroy() (u32, bpf, mall) hardcode true always instead of forwarding the parameter. A future cleanup should remove the rtnl_held parameter from the destroy callback signature entirely and have callers rely solely on their knowledge whether they are running in an unlocked context.

In the Linux kernel, the following vulnerability has been resolved: bnxt_en: Disable EOP for TPA on all chips to prevent data corruption EOP (End of frame padding) on the AGG ring may cause overlapping of zero padding at the end of one segment with the next segment's data. If Relaxed Ordering (RO) is enabled, the zero padding may overwrite valid data in the next segment and corrupt the data. Older chips (P5 and older) do not automatically disable RO when EOP is enabled. On some ARM systems, data corruption was reported on 57508 (P5) chips with RO enabled. Always disable EOP on all chips on the AGG rings when TPA is enabled to fix the data corruption.

In the Linux kernel, the following vulnerability has been resolved: tcp: fix TFO max_qlen accounting across reuseport migration A listener's TCP_FASTOPEN max_qlen stops being accurate and lets through far more pending Fast Open requests than it was configured for. This only shows up with SO_REUSEPORT listener migration, where closing a listener hands its still-pending TFO children over to a surviving one. fastopenq.qlen is charged in tcp_fastopen_create_child() when the child is created and uncharged in reqsk_fastopen_remove() when the handshake completes. The uncharge follows rsk_listener of the request the child points at, and inet_reqsk_clone() has repointed the child at a new request owned by the new listener, so the ++ and the -- land on two different sockets. The new listener's qlen drifts negative and its limit no longer binds. Charge the new listener during migration, like reqsk_queue_migrated() already does for queue->young and queue->qlen.

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_flow_table: drop existing skb dst before skb_dst_set_noref() Incoming skbs passing through netfilter flowtable offload hooks (or XFRM offload path) might already carry a ref-counted dst_entry assigned during earlier RX or routing steps. Calling skb_dst_set_noref() when skb already holds a ref-counted dst overwrites skb->_skb_refdst, leaking the previous dst_entry reference count and triggering a DEBUG_NET_WARN_ON_ONCE assertion in skb_dst_check_unset(): WARNING: at skb_dst_check_unset include/linux/skbuff.h:1170 WARNING: at skb_dst_set_noref include/linux/skbuff.h:1234 WARNING: at nf_flow_offload_ip_hook+0xf6c/0x2b60 net/netfilter/nf_flow_table_ip.c:864 Drop any existing dst_entry reference with skb_dst_drop(skb) before setting the non-referenced flowtable destination.

In the Linux kernel, the following vulnerability has been resolved: net/smc: fix TOCTOU race between smc_listen_out() and listener close smc_listen_out() reads lsmc->sk.sk_state without the listener lock, then acquires lock_sock_nested() only after the check passes. This opens a window where smc_close_active() can transition the listener to SMC_CLOSED, call smc_close_cleanup_listen() to drain the accept queue, and release the lock, all between the lockless read and the delayed lock acquisition: smc_listen_work (smc_hs_wq) smc_close_active() ------------------------------- ------------------------- release_sock(child) if (sk_state == SMC_LISTEN) TRUE lock_sock(listener) sk_state = SMC_CLOSED smc_close_cleanup_listen() release_sock(listener) flush_work(tcp_listen_work) lock_sock_nested(listener) smc_accept_enqueue(listener, child) /* child enqueued on dead listener */ smc_close_active() flushes only tcp_listen_work. Work items already dispatched onto smc_hs_wq for the CLC handshake continue running unguarded. smc_accept_enqueue() takes a sock_hold() on the child that is never released, so the child smc_sock, its clcsock, and the reference all leak. A remote peer that opens TCP connections while the server calls close() can exhaust kernel memory. Move lock_sock_nested() to before the sk_state check so that the test and the enqueue are atomic under the listener lock.

In the Linux kernel, the following vulnerability has been resolved: net: thunderbolt: Tear down DMA paths before stopping the rings tbnet_tear_down() stops both rings and frees their frame buffers before calling tb_xdomain_disable_paths(). tb_ring_stop() zeroes the ring's descriptor base and tbnet_free_buffers() unmaps and frees the pages the frames sit in, so by the time __tb_path_deactivate_hop() polls the hop's 'pending' bit, anything still in flight has nowhere to drain to. The teardown sequence has been in this order since the driver was added. The setup path has not: commit ff7cd07f3064 ("net: thunderbolt: Enable DMA paths only after rings are enabled") moved the path enable to the end of tbnet_connected_work() and documented why: /* Both logins successful so enable the rings, high-speed DMA * paths and start the network device queue. * * Note we enable the DMA paths last to make sure we have primed * the Rx ring before any incoming packets are allowed to * arrive. */ Teardown was never updated to match, so the rings and the paths now come down in the same order they go up instead of in reverse. On an ASMedia ASM4242 host router the 'pending' bit then never clears: every teardown burns the full 500 ms timeout and __tb_path_deactivate_hop() returns -ETIMEDOUT. Raising the timeout to 5 s does not help, so the hop is not slow to drain, it never drains at all. The failure is invisible above the thunderbolt core. __tb_path_deactivate_hops() is void and only calls tb_port_warn(); tb_path_deactivate(), tb_tunnel_deactivate() and __tb_disconnect_xdomain_paths() are void as well, and tb_disconnect_xdomain_paths() ends in an unconditional "return 0". So tb_xdomain_disable_paths() reports success and the netdev_warn() below it never fires. Repeated teardowns eventually take the XDomain control channel down, after which the peer node is gone and only a power cycle brings the controller back. Deactivating the paths first fixes it. Measured with kretprobes on a stock v6.17 tree with no other patches applied, on a link that was up and had just carried traffic: before: __tb_path_deactivate_hop() returns 0 for the first hop, then -ETIMEDOUT for the second 500335 us later after: 0 for both, 525 us apart Alternating the two orderings ABBA over three load levels, four teardowns per arm: every teardown failed before the change (21 of 21 that ran), none failed after (0 of 24). The before arms ran short because the link died partway through. The same split shows up when the interface is enslaved to a bond instead of just brought down, which is how I ran into this in the first place. Throughput and latency after the change are unchanged. Hosts whose routers drain the hop despite the stale descriptor base see no functional difference, since the paths end up deactivated either way.

In the Linux kernel, the following vulnerability has been resolved: s390/ism: Fix UAF of sba and ieq during ism_dev_exit() A ism interrupt handler can be active in parallel with ism_dev_exit(), accessing freed data structures. No new interrupts will be generated after unregister_ieq(). Drain ongoing interrupt handlers by free_irq(), before freeing ism data structures.

In the Linux kernel, the following vulnerability has been resolved: net/atm: fix slab-out-of-bounds read in vcc_setsockopt() vcc_setsockopt() contained an ineffective optlen check: if (__SO_LEVEL_MATCH(optname, level) && optlen != __SO_SIZE(optname)) return -EINVAL; If __SO_LEVEL_MATCH(optname, level) evaluated to false (e.g. if the caller passed a mismatched level), the length check optlen != __SO_SIZE(optname) was short-circuited and bypassed. Execution then fell through to switch(optname), calling copy_from_sockptr() assuming optval contained sufficient space. Furthermore, even if level matched, a cgroup BPF setsockopt filter could shrink optlen after entry. Because copy_from_sockptr() on kernel pointers uses memcpy(), this leads to a KASAN slab-out-of-bounds read when optlen is smaller than the expected structure size. Fix this by using copy_safe_from_sockptr(), which unconditionally validates that optlen is at least the expected size before copying. Also change the local 'value' variable type from 'unsigned long' to 'int' so that SO_SETCLP matches its sizeof(int) ABI encoding on 64-bit systems.

In the Linux kernel, the following vulnerability has been resolved: watchdog: at91sam9_wdt: prevent timer rearm during teardown at91_ping() rearms the watchdog timer from its callback. timer_delete() neither waits for a running callback nor prevents it from rearming the timer, so probe failure or driver removal can leave the timer accessing the devm-allocated at91wdt after it has been freed. Use timer_shutdown_sync() on both teardown paths. It waits for a running callback and rejects any attempt by the callback to rearm the timer.

In the Linux kernel, the following vulnerability has been resolved: net: tap: set skb->dev before parsing virtio net header in tap_get_user_xdp() The commit 4f61f133f354 ("net: tap: NULL pointer derefence in dev_parse_header_protocol when skb->dev is null") fixed a crash in tap_get_user() by assigning skb->dev before calling tun_vnet_hdr_to_skb(). This is required because virtio_net_hdr_to_skb() may invoke dev_parse_header_protocol(), which dereferences skb->dev. Without the assignment, a NULL pointer dereference can occur. However, tap_get_user_xdp() still parses the virtio-net header before assigning skb->dev. When the vhost TX path passes an XDP buffer containing a GSO virtio-net header but the protocol is set to zero on purpose, tun_vnet_hdr_to_skb() can reach dev_parse_header_protocol() while skb->dev is still NULL, resulting in a crash. Fix this by looking up the tap device and assigning skb->dev before calling tun_vnet_hdr_to_skb(), matching the ordering already used in tap_get_user(). Preserve the existing RCU read-side critical section across dev_queue_xmit().