user/sven/linux.git/include, branch v5.10.86

PM: runtime: Fix pm_runtime_active() kerneldoc comment

2021-12-14T10:32:41Z

commit 444dd878e85fb33fcfb2682cfdab4c236f33ea3e upstream. The kerneldoc comment of pm_runtime_active() does not reflect the behavior of the function, so update it accordingly. Fixes: 403d2d116ec0 ("PM: runtime: Add kerneldoc comments to multiple helpers") Signed-off-by: Rafael J. Wysocki Reviewed-by: Ulf Hansson Signed-off-by: Greg Kroah-Hartman

aio: fix use-after-free due to missing POLLFREE handling

2021-12-14T10:32:40Z

commit 50252e4b5e989ce64555c7aef7516bdefc2fea72 upstream. signalfd_poll() and binder_poll() are special in that they use a waitqueue whose lifetime is the current task, rather than the struct file as is normally the case. This is okay for blocking polls, since a blocking poll occurs within one task; however, non-blocking polls require another solution. This solution is for the queue to be cleared before it is freed, by sending a POLLFREE notification to all waiters. Unfortunately, only eventpoll handles POLLFREE. A second type of non-blocking poll, aio poll, was added in kernel v4.18, and it doesn't handle POLLFREE. This allows a use-after-free to occur if a signalfd or binder fd is polled with aio poll, and the waitqueue gets freed. Fix this by making aio poll handle POLLFREE. A patch by Ramji Jiyani (https://lore.kernel.org/r/20211027011834.2497484-1-ramjiyani@google.com) tried to do this by making aio_poll_wake() always complete the request inline if POLLFREE is seen. However, that solution had two bugs. First, it introduced a deadlock, as it unconditionally locked the aio context while holding the waitqueue lock, which inverts the normal locking order. Second, it didn't consider that POLLFREE notifications are missed while the request has been temporarily de-queued. The second problem was solved by my previous patch. This patch then properly fixes the use-after-free by handling POLLFREE in a deadlock-free way. It does this by taking advantage of the fact that freeing of the waitqueue is RCU-delayed, similar to what eventpoll does. Fixes: 2c14fa838cbe ("aio: implement IOCB_CMD_POLL") Cc: # v4.18+ Link: https://lore.kernel.org/r/20211209010455.42744-6-ebiggers@kernel.org Signed-off-by: Eric Biggers Signed-off-by: Greg Kroah-Hartman

wait: add wake_up_pollfree()

2021-12-14T10:32:39Z

commit 42288cb44c4b5fff7653bc392b583a2b8bd6a8c0 upstream. Several ->poll() implementations are special in that they use a waitqueue whose lifetime is the current task, rather than the struct file as is normally the case. This is okay for blocking polls, since a blocking poll occurs within one task; however, non-blocking polls require another solution. This solution is for the queue to be cleared before it is freed, using 'wake_up_poll(wq, EPOLLHUP | POLLFREE);'. However, that has a bug: wake_up_poll() calls __wake_up() with nr_exclusive=1. Therefore, if there are multiple "exclusive" waiters, and the wakeup function for the first one returns a positive value, only that one will be called. That's *not* what's needed for POLLFREE; POLLFREE is special in that it really needs to wake up everyone. Considering the three non-blocking poll systems: - io_uring poll doesn't handle POLLFREE at all, so it is broken anyway. - aio poll is unaffected, since it doesn't support exclusive waits. However, that's fragile, as someone could add this feature later. - epoll doesn't appear to be broken by this, since its wakeup function returns 0 when it sees POLLFREE. But this is fragile. Although there is a workaround (see epoll), it's better to define a function which always sends POLLFREE to all waiters. Add such a function. Also make it verify that the queue really becomes empty after all waiters have been woken up. Reported-by: Linus Torvalds Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20211209010455.42744-2-ebiggers@kernel.org Signed-off-by: Eric Biggers Signed-off-by: Greg Kroah-Hartman

netfilter: conntrack: annotate data-races around ct->timeout

2021-12-14T10:32:37Z

commit 802a7dc5cf1bef06f7b290ce76d478138408d6b1 upstream. (struct nf_conn)->timeout can be read/written locklessly, add READ_ONCE()/WRITE_ONCE() to prevent load/store tearing. BUG: KCSAN: data-race in __nf_conntrack_alloc / __nf_conntrack_find_get write to 0xffff888132e78c08 of 4 bytes by task 6029 on cpu 0: __nf_conntrack_alloc+0x158/0x280 net/netfilter/nf_conntrack_core.c:1563 init_conntrack+0x1da/0xb30 net/netfilter/nf_conntrack_core.c:1635 resolve_normal_ct+0x502/0x610 net/netfilter/nf_conntrack_core.c:1746 nf_conntrack_in+0x1c5/0x88f net/netfilter/nf_conntrack_core.c:1901 ipv6_conntrack_local+0x19/0x20 net/netfilter/nf_conntrack_proto.c:414 nf_hook_entry_hookfn include/linux/netfilter.h:142 [inline] nf_hook_slow+0x72/0x170 net/netfilter/core.c:619 nf_hook include/linux/netfilter.h:262 [inline] NF_HOOK include/linux/netfilter.h:305 [inline] ip6_xmit+0xa3a/0xa60 net/ipv6/ip6_output.c:324 inet6_csk_xmit+0x1a2/0x1e0 net/ipv6/inet6_connection_sock.c:135 __tcp_transmit_skb+0x132a/0x1840 net/ipv4/tcp_output.c:1402 tcp_transmit_skb net/ipv4/tcp_output.c:1420 [inline] tcp_write_xmit+0x1450/0x4460 net/ipv4/tcp_output.c:2680 __tcp_push_pending_frames+0x68/0x1c0 net/ipv4/tcp_output.c:2864 tcp_push_pending_frames include/net/tcp.h:1897 [inline] tcp_data_snd_check+0x62/0x2e0 net/ipv4/tcp_input.c:5452 tcp_rcv_established+0x880/0x10e0 net/ipv4/tcp_input.c:5947 tcp_v6_do_rcv+0x36e/0xa50 net/ipv6/tcp_ipv6.c:1521 sk_backlog_rcv include/net/sock.h:1030 [inline] __release_sock+0xf2/0x270 net/core/sock.c:2768 release_sock+0x40/0x110 net/core/sock.c:3300 sk_stream_wait_memory+0x435/0x700 net/core/stream.c:145 tcp_sendmsg_locked+0xb85/0x25a0 net/ipv4/tcp.c:1402 tcp_sendmsg+0x2c/0x40 net/ipv4/tcp.c:1440 inet6_sendmsg+0x5f/0x80 net/ipv6/af_inet6.c:644 sock_sendmsg_nosec net/socket.c:704 [inline] sock_sendmsg net/socket.c:724 [inline] __sys_sendto+0x21e/0x2c0 net/socket.c:2036 __do_sys_sendto net/socket.c:2048 [inline] __se_sys_sendto net/socket.c:2044 [inline] __x64_sys_sendto+0x74/0x90 net/socket.c:2044 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae read to 0xffff888132e78c08 of 4 bytes by task 17446 on cpu 1: nf_ct_is_expired include/net/netfilter/nf_conntrack.h:286 [inline] ____nf_conntrack_find net/netfilter/nf_conntrack_core.c:776 [inline] __nf_conntrack_find_get+0x1c7/0xac0 net/netfilter/nf_conntrack_core.c:807 resolve_normal_ct+0x273/0x610 net/netfilter/nf_conntrack_core.c:1734 nf_conntrack_in+0x1c5/0x88f net/netfilter/nf_conntrack_core.c:1901 ipv6_conntrack_local+0x19/0x20 net/netfilter/nf_conntrack_proto.c:414 nf_hook_entry_hookfn include/linux/netfilter.h:142 [inline] nf_hook_slow+0x72/0x170 net/netfilter/core.c:619 nf_hook include/linux/netfilter.h:262 [inline] NF_HOOK include/linux/netfilter.h:305 [inline] ip6_xmit+0xa3a/0xa60 net/ipv6/ip6_output.c:324 inet6_csk_xmit+0x1a2/0x1e0 net/ipv6/inet6_connection_sock.c:135 __tcp_transmit_skb+0x132a/0x1840 net/ipv4/tcp_output.c:1402 __tcp_send_ack+0x1fd/0x300 net/ipv4/tcp_output.c:3956 tcp_send_ack+0x23/0x30 net/ipv4/tcp_output.c:3962 __tcp_ack_snd_check+0x2d8/0x510 net/ipv4/tcp_input.c:5478 tcp_ack_snd_check net/ipv4/tcp_input.c:5523 [inline] tcp_rcv_established+0x8c2/0x10e0 net/ipv4/tcp_input.c:5948 tcp_v6_do_rcv+0x36e/0xa50 net/ipv6/tcp_ipv6.c:1521 sk_backlog_rcv include/net/sock.h:1030 [inline] __release_sock+0xf2/0x270 net/core/sock.c:2768 release_sock+0x40/0x110 net/core/sock.c:3300 tcp_sendpage+0x94/0xb0 net/ipv4/tcp.c:1114 inet_sendpage+0x7f/0xc0 net/ipv4/af_inet.c:833 rds_tcp_xmit+0x376/0x5f0 net/rds/tcp_send.c:118 rds_send_xmit+0xbed/0x1500 net/rds/send.c:367 rds_send_worker+0x43/0x200 net/rds/threads.c:200 process_one_work+0x3fc/0x980 kernel/workqueue.c:2298 worker_thread+0x616/0xa70 kernel/workqueue.c:2445 kthread+0x2c7/0x2e0 kernel/kthread.c:327 ret_from_fork+0x1f/0x30 value changed: 0x00027cc2 -> 0x00000000 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 17446 Comm: kworker/u4:5 Tainted: G W 5.16.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: krdsd rds_send_worker Note: I chose an arbitrary commit for the Fixes: tag, because I do not think we need to backport this fix to very old kernels. Fixes: e37542ba111f ("netfilter: conntrack: avoid possible false sharing") Signed-off-by: Eric Dumazet Reported-by: syzbot Signed-off-by: Pablo Neira Ayuso Signed-off-by: Greg Kroah-Hartman

bonding: make tx_rebalance_counter an atomic

2021-12-14T10:32:36Z

commit dac8e00fb640e9569cdeefd3ce8a75639e5d0711 upstream. KCSAN reported a data-race [1] around tx_rebalance_counter which can be accessed from different contexts, without the protection of a lock/mutex. [1] BUG: KCSAN: data-race in bond_alb_init_slave / bond_alb_monitor write to 0xffff888157e8ca24 of 4 bytes by task 7075 on cpu 0: bond_alb_init_slave+0x713/0x860 drivers/net/bonding/bond_alb.c:1613 bond_enslave+0xd94/0x3010 drivers/net/bonding/bond_main.c:1949 do_set_master net/core/rtnetlink.c:2521 [inline] __rtnl_newlink net/core/rtnetlink.c:3475 [inline] rtnl_newlink+0x1298/0x13b0 net/core/rtnetlink.c:3506 rtnetlink_rcv_msg+0x745/0x7e0 net/core/rtnetlink.c:5571 netlink_rcv_skb+0x14e/0x250 net/netlink/af_netlink.c:2491 rtnetlink_rcv+0x18/0x20 net/core/rtnetlink.c:5589 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x5fc/0x6c0 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x6e1/0x7d0 net/netlink/af_netlink.c:1916 sock_sendmsg_nosec net/socket.c:704 [inline] sock_sendmsg net/socket.c:724 [inline] ____sys_sendmsg+0x39a/0x510 net/socket.c:2409 ___sys_sendmsg net/socket.c:2463 [inline] __sys_sendmsg+0x195/0x230 net/socket.c:2492 __do_sys_sendmsg net/socket.c:2501 [inline] __se_sys_sendmsg net/socket.c:2499 [inline] __x64_sys_sendmsg+0x42/0x50 net/socket.c:2499 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae read to 0xffff888157e8ca24 of 4 bytes by task 1082 on cpu 1: bond_alb_monitor+0x8f/0xc00 drivers/net/bonding/bond_alb.c:1511 process_one_work+0x3fc/0x980 kernel/workqueue.c:2298 worker_thread+0x616/0xa70 kernel/workqueue.c:2445 kthread+0x2c7/0x2e0 kernel/kthread.c:327 ret_from_fork+0x1f/0x30 value changed: 0x00000001 -> 0x00000064 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 1082 Comm: kworker/u4:3 Not tainted 5.16.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bond1 bond_alb_monitor Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet Reported-by: syzbot Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

bpf, x86: Fix "no previous prototype" warning

2021-12-14T10:32:36Z

commit f45b2974cc0ae959a4c503a071e38a56bd64372f upstream. The arch_prepare_bpf_dispatcher function does not have a prototype, and yields the following warning when W=1 is enabled for the kernel build. >> arch/x86/net/bpf_jit_comp.c:2188:5: warning: no previous \ prototype for 'arch_prepare_bpf_dispatcher' [-Wmissing-prototypes] 2188 | int arch_prepare_bpf_dispatcher(void *image, s64 *funcs, \ int num_funcs) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ Remove the warning by adding a function declaration to include/linux/bpf.h. Fixes: 75ccbef6369e ("bpf: Introduce BPF dispatcher") Reported-by: kernel test robot Signed-off-by: Björn Töpel Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20211117125708.769168-1-bjorn@kernel.org Signed-off-by: Greg Kroah-Hartman

HID: add hid_is_usb() function to make it simpler for USB detection

2021-12-14T10:32:33Z

commit f83baa0cb6cfc92ebaf7f9d3a99d7e34f2e77a8a upstream. A number of HID drivers already call hid_is_using_ll_driver() but only for the detection of if this is a USB device or not. Make this more obvious by creating hid_is_usb() and calling the function that way. Also converts the existing hid_is_using_ll_driver() functions to use the new call. Cc: Jiri Kosina Cc: Benjamin Tissoires Cc: linux-input@vger.kernel.org Cc: stable@vger.kernel.org Tested-by: Benjamin Tissoires Signed-off-by: Greg Kroah-Hartman Signed-off-by: Benjamin Tissoires Link: https://lore.kernel.org/r/20211201183503.2373082-1-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman

ipv4: convert fib_num_tclassid_users to atomic_t

2021-12-08T08:03:26Z

commit 213f5f8f31f10aa1e83187ae20fb7fa4e626b724 upstream. Before commit faa041a40b9f ("ipv4: Create cleanup helper for fib_nh") changes to net->ipv4.fib_num_tclassid_users were protected by RTNL. After the change, this is no longer the case, as free_fib_info_rcu() runs after rcu grace period, without rtnl being held. Fixes: faa041a40b9f ("ipv4: Create cleanup helper for fib_nh") Signed-off-by: Eric Dumazet Cc: David Ahern Reviewed-by: David Ahern Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

net: annotate data-races on txq->xmit_lock_owner

2021-12-08T08:03:25Z

commit 7a10d8c810cfad3e79372d7d1c77899d86cd6662 upstream. syzbot found that __dev_queue_xmit() is reading txq->xmit_lock_owner without annotations. No serious issue there, let's document what is happening there. BUG: KCSAN: data-race in __dev_queue_xmit / __dev_queue_xmit write to 0xffff888139d09484 of 4 bytes by interrupt on cpu 0: __netif_tx_unlock include/linux/netdevice.h:4437 [inline] __dev_queue_xmit+0x948/0xf70 net/core/dev.c:4229 dev_queue_xmit_accel+0x19/0x20 net/core/dev.c:4265 macvlan_queue_xmit drivers/net/macvlan.c:543 [inline] macvlan_start_xmit+0x2b3/0x3d0 drivers/net/macvlan.c:567 __netdev_start_xmit include/linux/netdevice.h:4987 [inline] netdev_start_xmit include/linux/netdevice.h:5001 [inline] xmit_one+0x105/0x2f0 net/core/dev.c:3590 dev_hard_start_xmit+0x72/0x120 net/core/dev.c:3606 sch_direct_xmit+0x1b2/0x7c0 net/sched/sch_generic.c:342 __dev_xmit_skb+0x83d/0x1370 net/core/dev.c:3817 __dev_queue_xmit+0x590/0xf70 net/core/dev.c:4194 dev_queue_xmit+0x13/0x20 net/core/dev.c:4259 neigh_hh_output include/net/neighbour.h:511 [inline] neigh_output include/net/neighbour.h:525 [inline] ip6_finish_output2+0x995/0xbb0 net/ipv6/ip6_output.c:126 __ip6_finish_output net/ipv6/ip6_output.c:191 [inline] ip6_finish_output+0x444/0x4c0 net/ipv6/ip6_output.c:201 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip6_output+0x10e/0x210 net/ipv6/ip6_output.c:224 dst_output include/net/dst.h:450 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] ndisc_send_skb+0x486/0x610 net/ipv6/ndisc.c:508 ndisc_send_rs+0x3b0/0x3e0 net/ipv6/ndisc.c:702 addrconf_rs_timer+0x370/0x540 net/ipv6/addrconf.c:3898 call_timer_fn+0x2e/0x240 kernel/time/timer.c:1421 expire_timers+0x116/0x240 kernel/time/timer.c:1466 __run_timers+0x368/0x410 kernel/time/timer.c:1734 run_timer_softirq+0x2e/0x60 kernel/time/timer.c:1747 __do_softirq+0x158/0x2de kernel/softirq.c:558 __irq_exit_rcu kernel/softirq.c:636 [inline] irq_exit_rcu+0x37/0x70 kernel/softirq.c:648 sysvec_apic_timer_interrupt+0x3e/0xb0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 read to 0xffff888139d09484 of 4 bytes by interrupt on cpu 1: __dev_queue_xmit+0x5e3/0xf70 net/core/dev.c:4213 dev_queue_xmit_accel+0x19/0x20 net/core/dev.c:4265 macvlan_queue_xmit drivers/net/macvlan.c:543 [inline] macvlan_start_xmit+0x2b3/0x3d0 drivers/net/macvlan.c:567 __netdev_start_xmit include/linux/netdevice.h:4987 [inline] netdev_start_xmit include/linux/netdevice.h:5001 [inline] xmit_one+0x105/0x2f0 net/core/dev.c:3590 dev_hard_start_xmit+0x72/0x120 net/core/dev.c:3606 sch_direct_xmit+0x1b2/0x7c0 net/sched/sch_generic.c:342 __dev_xmit_skb+0x83d/0x1370 net/core/dev.c:3817 __dev_queue_xmit+0x590/0xf70 net/core/dev.c:4194 dev_queue_xmit+0x13/0x20 net/core/dev.c:4259 neigh_resolve_output+0x3db/0x410 net/core/neighbour.c:1523 neigh_output include/net/neighbour.h:527 [inline] ip6_finish_output2+0x9be/0xbb0 net/ipv6/ip6_output.c:126 __ip6_finish_output net/ipv6/ip6_output.c:191 [inline] ip6_finish_output+0x444/0x4c0 net/ipv6/ip6_output.c:201 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip6_output+0x10e/0x210 net/ipv6/ip6_output.c:224 dst_output include/net/dst.h:450 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] ndisc_send_skb+0x486/0x610 net/ipv6/ndisc.c:508 ndisc_send_rs+0x3b0/0x3e0 net/ipv6/ndisc.c:702 addrconf_rs_timer+0x370/0x540 net/ipv6/addrconf.c:3898 call_timer_fn+0x2e/0x240 kernel/time/timer.c:1421 expire_timers+0x116/0x240 kernel/time/timer.c:1466 __run_timers+0x368/0x410 kernel/time/timer.c:1734 run_timer_softirq+0x2e/0x60 kernel/time/timer.c:1747 __do_softirq+0x158/0x2de kernel/softirq.c:558 __irq_exit_rcu kernel/softirq.c:636 [inline] irq_exit_rcu+0x37/0x70 kernel/softirq.c:648 sysvec_apic_timer_interrupt+0x8d/0xb0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 kcsan_setup_watchpoint+0x94/0x420 kernel/kcsan/core.c:443 folio_test_anon include/linux/page-flags.h:581 [inline] PageAnon include/linux/page-flags.h:586 [inline] zap_pte_range+0x5ac/0x10e0 mm/memory.c:1347 zap_pmd_range mm/memory.c:1467 [inline] zap_pud_range mm/memory.c:1496 [inline] zap_p4d_range mm/memory.c:1517 [inline] unmap_page_range+0x2dc/0x3d0 mm/memory.c:1538 unmap_single_vma+0x157/0x210 mm/memory.c:1583 unmap_vmas+0xd0/0x180 mm/memory.c:1615 exit_mmap+0x23d/0x470 mm/mmap.c:3170 __mmput+0x27/0x1b0 kernel/fork.c:1113 mmput+0x3d/0x50 kernel/fork.c:1134 exit_mm+0xdb/0x170 kernel/exit.c:507 do_exit+0x608/0x17a0 kernel/exit.c:819 do_group_exit+0xce/0x180 kernel/exit.c:929 get_signal+0xfc3/0x1550 kernel/signal.c:2852 arch_do_signal_or_restart+0x8c/0x2e0 arch/x86/kernel/signal.c:868 handle_signal_work kernel/entry/common.c:148 [inline] exit_to_user_mode_loop kernel/entry/common.c:172 [inline] exit_to_user_mode_prepare+0x113/0x190 kernel/entry/common.c:207 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:300 do_syscall_64+0x50/0xd0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae value changed: 0x00000000 -> 0xffffffff Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 28712 Comm: syz-executor.0 Tainted: G W 5.16.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet Reported-by: syzbot Link: https://lore.kernel.org/r/20211130170155.2331929-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

siphash: use _unaligned version by default

2021-12-08T08:03:23Z

commit f7e5b9bfa6c8820407b64eabc1f29c9a87e8993d upstream. On ARM v6 and later, we define CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS because the ordinary load/store instructions (ldr, ldrh, ldrb) can tolerate any misalignment of the memory address. However, load/store double and load/store multiple instructions (ldrd, ldm) may still only be used on memory addresses that are 32-bit aligned, and so we have to use the CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS macro with care, or we may end up with a severe performance hit due to alignment traps that require fixups by the kernel. Testing shows that this currently happens with clang-13 but not gcc-11. In theory, any compiler version can produce this bug or other problems, as we are dealing with undefined behavior in C99 even on architectures that support this in hardware, see also https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100363. Fortunately, the get_unaligned() accessors do the right thing: when building for ARMv6 or later, the compiler will emit unaligned accesses using the ordinary load/store instructions (but avoid the ones that require 32-bit alignment). When building for older ARM, those accessors will emit the appropriate sequence of ldrb/mov/orr instructions. And on architectures that can truly tolerate any kind of misalignment, the get_unaligned() accessors resolve to the leXX_to_cpup accessors that operate on aligned addresses. Since the compiler will in fact emit ldrd or ldm instructions when building this code for ARM v6 or later, the solution is to use the unaligned accessors unconditionally on architectures where this is known to be fast. The _aligned version of the hash function is however still needed to get the best performance on architectures that cannot do any unaligned access in hardware. This new version avoids the undefined behavior and should produce the fastest hash on all architectures we support. Link: https://lore.kernel.org/linux-arm-kernel/20181008211554.5355-4-ard.biesheuvel@linaro.org/ Link: https://lore.kernel.org/linux-crypto/CAK8P3a2KfmmGDbVHULWevB0hv71P2oi2ZCHEAqT=8dQfa0=cqQ@mail.gmail.com/ Reported-by: Ard Biesheuvel Fixes: 2c956a60778c ("siphash: add cryptographically secure PRF") Signed-off-by: Arnd Bergmann Reviewed-by: Jason A. Donenfeld Acked-by: Ard Biesheuvel Signed-off-by: Jason A. Donenfeld Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman