Search

Search Results (395130 CVEs found)

CVE Vendors Products Updated CVSS v3.1
CVE-2025-37801 1 Linux 1 Linux Kernel 2026-10-15 7.8 High
In the Linux kernel, the following vulnerability has been resolved: spi: spi-imx: Add check for spi_imx_setupxfer() Add check for the return value of spi_imx_setupxfer(). spi_imx->rx and spi_imx->tx function pointer can be NULL when spi_imx_setupxfer() return error, and make NULL pointer dereference. Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 Call trace: 0x0 spi_imx_pio_transfer+0x50/0xd8 spi_imx_transfer_one+0x18c/0x858 spi_transfer_one_message+0x43c/0x790 __spi_pump_transfer_message+0x238/0x5d4 __spi_sync+0x2b0/0x454 spi_write_then_read+0x11c/0x200
CVE-2025-37800 1 Linux 1 Linux Kernel 2026-10-15 7.1 High
In the Linux kernel, the following vulnerability has been resolved: driver core: fix potential NULL pointer dereference in dev_uevent() If userspace reads "uevent" device attribute at the same time as another threads unbinds the device from its driver, change to dev->driver from a valid pointer to NULL may result in crash. Fix this by using READ_ONCE() when fetching the pointer, and take bus' drivers klist lock to make sure driver instance will not disappear while we access it. Use WRITE_ONCE() when setting the driver pointer to ensure there is no tearing.
CVE-2025-37791 1 Linux 1 Linux Kernel 2026-10-15 7.8 High
In the Linux kernel, the following vulnerability has been resolved: ethtool: cmis_cdb: use correct rpl size in ethtool_cmis_module_poll() rpl is passed as a pointer to ethtool_cmis_module_poll(), so the correct size of rpl is sizeof(*rpl) which should be just 1 byte. Using the pointer size instead can cause stack corruption: Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: ethtool_cmis_wait_for_cond+0xf4/0x100 CPU: 72 UID: 0 PID: 4440 Comm: kworker/72:2 Kdump: loaded Tainted: G OE 6.11.0 #24 Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE Hardware name: Dell Inc. PowerEdge R760/04GWWM, BIOS 1.6.6 09/20/2023 Workqueue: events module_flash_fw_work Call Trace: <TASK> panic+0x339/0x360 ? ethtool_cmis_wait_for_cond+0xf4/0x100 ? __pfx_status_success+0x10/0x10 ? __pfx_status_fail+0x10/0x10 __stack_chk_fail+0x10/0x10 ethtool_cmis_wait_for_cond+0xf4/0x100 ethtool_cmis_cdb_execute_cmd+0x1fc/0x330 ? __pfx_status_fail+0x10/0x10 cmis_cdb_module_features_get+0x6d/0xd0 ethtool_cmis_cdb_init+0x8a/0xd0 ethtool_cmis_fw_update+0x46/0x1d0 module_flash_fw_work+0x17/0xa0 process_one_work+0x179/0x390 worker_thread+0x239/0x340 ? __pfx_worker_thread+0x10/0x10 kthread+0xcc/0x100 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x2d/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 </TASK>
CVE-2025-23142 2 Debian, Linux 2 Debian Linux, Linux Kernel 2026-10-15 7.8 High
In the Linux kernel, the following vulnerability has been resolved: sctp: detect and prevent references to a freed transport in sendmsg sctp_sendmsg() re-uses associations and transports when possible by doing a lookup based on the socket endpoint and the message destination address, and then sctp_sendmsg_to_asoc() sets the selected transport in all the message chunks to be sent. There's a possible race condition if another thread triggers the removal of that selected transport, for instance, by explicitly unbinding an address with setsockopt(SCTP_SOCKOPT_BINDX_REM), after the chunks have been set up and before the message is sent. This can happen if the send buffer is full, during the period when the sender thread temporarily releases the socket lock in sctp_wait_for_sndbuf(). This causes the access to the transport data in sctp_outq_select_transport(), when the association outqueue is flushed, to result in a use-after-free read. This change avoids this scenario by having sctp_transport_free() signal the freeing of the transport, tagging it as "dead". In order to do this, the patch restores the "dead" bit in struct sctp_transport, which was removed in commit 47faa1e4c50e ("sctp: remove the dead field of sctp_transport"). Then, in the scenario where the sender thread has released the socket lock in sctp_wait_for_sndbuf(), the bit is checked again after re-acquiring the socket lock to detect the deletion. This is done while holding a reference to the transport to prevent it from being freed in the process. If the transport was deleted while the socket lock was relinquished, sctp_sendmsg_to_asoc() will return -EAGAIN to let userspace retry the send. The bug was found by a private syzbot instance (see the error report [1] and the C reproducer that triggers it [2]).
CVE-2025-22077 1 Linux 1 Linux Kernel 2026-10-15 9.8 Critical
In the Linux kernel, the following vulnerability has been resolved: Revert "smb: client: fix TCP timers deadlock after rmmod" This reverts commit e9f2517a3e18a54a3943c098d2226b245d488801. Commit e9f2517a3e18 ("smb: client: fix TCP timers deadlock after rmmod") is intended to fix a null-ptr-deref in LOCKDEP, which is mentioned as CVE-2024-54680, but is actually did not fix anything; The issue can be reproduced on top of it. [0] Also, it reverted the change by commit ef7134c7fc48 ("smb: client: Fix use-after-free of network namespace.") and introduced a real issue by reviving the kernel TCP socket. When a reconnect happens for a CIFS connection, the socket state transitions to FIN_WAIT_1. Then, inet_csk_clear_xmit_timers_sync() in tcp_close() stops all timers for the socket. If an incoming FIN packet is lost, the socket will stay at FIN_WAIT_1 forever, and such sockets could be leaked up to net.ipv4.tcp_max_orphans. Usually, FIN can be retransmitted by the peer, but if the peer aborts the connection, the issue comes into reality. I warned about this privately by pointing out the exact report [1], but the bogus fix was finally merged. So, we should not stop the timers to finally kill the connection on our side in that case, meaning we must not use a kernel socket for TCP whose sk->sk_net_refcnt is 0. The kernel socket does not have a reference to its netns to make it possible to tear down netns without cleaning up every resource in it. For example, tunnel devices use a UDP socket internally, but we can destroy netns without removing such devices and let it complete during exit. Otherwise, netns would be leaked when the last application died. However, this is problematic for TCP sockets because TCP has timers to close the connection gracefully even after the socket is close()d. The lifetime of the socket and its netns is different from the lifetime of the underlying connection. If the socket user does not maintain the netns lifetime, the timer could be fired after the socket is close()d and its netns is freed up, resulting in use-after-free. Actually, we have seen so many similar issues and converted such sockets to have a reference to netns. That's why I converted the CIFS client socket to have a reference to netns (sk->sk_net_refcnt == 1), which is somehow mentioned as out-of-scope of CIFS and technically wrong in e9f2517a3e18, but **is in-scope and right fix**. Regarding the LOCKDEP issue, we can prevent the module unload by bumping the module refcount when switching the LOCKDDEP key in sock_lock_init_class_and_name(). [2] For a while, let's revert the bogus fix. Note that now we can use sk_net_refcnt_upgrade() for the socket conversion, but I'll do so later separately to make backport easy.
CVE-2025-22025 1 Linux 1 Linux Kernel 2026-10-15 7.5 High
In the Linux kernel, the following vulnerability has been resolved: nfsd: put dl_stid if fail to queue dl_recall Before calling nfsd4_run_cb to queue dl_recall to the callback_wq, we increment the reference count of dl_stid. We expect that after the corresponding work_struct is processed, the reference count of dl_stid will be decremented through the callback function nfsd4_cb_recall_release. However, if the call to nfsd4_run_cb fails, the incremented reference count of dl_stid will not be decremented correspondingly, leading to the following nfs4_stid leak: unreferenced object 0xffff88812067b578 (size 344): comm "nfsd", pid 2761, jiffies 4295044002 (age 5541.241s) hex dump (first 32 bytes): 01 00 00 00 6b 6b 6b 6b b8 02 c0 e2 81 88 ff ff ....kkkk........ 00 6b 6b 6b 6b 6b 6b 6b 00 00 00 00 ad 4e ad de .kkkkkkk.....N.. backtrace: kmem_cache_alloc+0x4b9/0x700 nfsd4_process_open1+0x34/0x300 nfsd4_open+0x2d1/0x9d0 nfsd4_proc_compound+0x7a2/0xe30 nfsd_dispatch+0x241/0x3e0 svc_process_common+0x5d3/0xcc0 svc_process+0x2a3/0x320 nfsd+0x180/0x2e0 kthread+0x199/0x1d0 ret_from_fork+0x30/0x50 ret_from_fork_asm+0x1b/0x30 unreferenced object 0xffff8881499f4d28 (size 368): comm "nfsd", pid 2761, jiffies 4295044005 (age 5541.239s) hex dump (first 32 bytes): 01 00 00 00 00 00 00 00 30 4d 9f 49 81 88 ff ff ........0M.I.... 30 4d 9f 49 81 88 ff ff 20 00 00 00 01 00 00 00 0M.I.... ....... backtrace: kmem_cache_alloc+0x4b9/0x700 nfs4_alloc_stid+0x29/0x210 alloc_init_deleg+0x92/0x2e0 nfs4_set_delegation+0x284/0xc00 nfs4_open_delegation+0x216/0x3f0 nfsd4_process_open2+0x2b3/0xee0 nfsd4_open+0x770/0x9d0 nfsd4_proc_compound+0x7a2/0xe30 nfsd_dispatch+0x241/0x3e0 svc_process_common+0x5d3/0xcc0 svc_process+0x2a3/0x320 nfsd+0x180/0x2e0 kthread+0x199/0x1d0 ret_from_fork+0x30/0x50 ret_from_fork_asm+0x1b/0x30 Fix it by checking the result of nfsd4_run_cb and call nfs4_put_stid if fail to queue dl_recall.
CVE-2025-21971 1 Linux 1 Linux Kernel 2026-10-15 7.8 High
In the Linux kernel, the following vulnerability has been resolved: net_sched: Prevent creation of classes with TC_H_ROOT The function qdisc_tree_reduce_backlog() uses TC_H_ROOT as a termination condition when traversing up the qdisc tree to update parent backlog counters. However, if a class is created with classid TC_H_ROOT, the traversal terminates prematurely at this class instead of reaching the actual root qdisc, causing parent statistics to be incorrectly maintained. In case of DRR, this could lead to a crash as reported by Mingi Cho. Prevent the creation of any Qdisc class with classid TC_H_ROOT (0xFFFFFFFF) across all qdisc types, as suggested by Jamal.
CVE-2025-21924 1 Linux 1 Linux Kernel 2026-10-15 7.8 High
In the Linux kernel, the following vulnerability has been resolved: net: hns3: make sure ptp clock is unregister and freed if hclge_ptp_get_cycle returns an error During the initialization of ptp, hclge_ptp_get_cycle might return an error and returned directly without unregister clock and free it. To avoid that, call hclge_ptp_destroy_clock to unregist and free clock if hclge_ptp_get_cycle failed.
CVE-2025-21876 1 Linux 1 Linux Kernel 2026-10-15 8.8 High
In the Linux kernel, the following vulnerability has been resolved: iommu/vt-d: Fix suspicious RCU usage Commit <d74169ceb0d2> ("iommu/vt-d: Allocate DMAR fault interrupts locally") moved the call to enable_drhd_fault_handling() to a code path that does not hold any lock while traversing the drhd list. Fix it by ensuring the dmar_global_lock lock is held when traversing the drhd list. Without this fix, the following warning is triggered: ============================= WARNING: suspicious RCU usage 6.14.0-rc3 #55 Not tainted ----------------------------- drivers/iommu/intel/dmar.c:2046 RCU-list traversed in non-reader section!! other info that might help us debug this: rcu_scheduler_active = 1, debug_locks = 1 2 locks held by cpuhp/1/23: #0: ffffffff84a67c50 (cpu_hotplug_lock){++++}-{0:0}, at: cpuhp_thread_fun+0x87/0x2c0 #1: ffffffff84a6a380 (cpuhp_state-up){+.+.}-{0:0}, at: cpuhp_thread_fun+0x87/0x2c0 stack backtrace: CPU: 1 UID: 0 PID: 23 Comm: cpuhp/1 Not tainted 6.14.0-rc3 #55 Call Trace: <TASK> dump_stack_lvl+0xb7/0xd0 lockdep_rcu_suspicious+0x159/0x1f0 ? __pfx_enable_drhd_fault_handling+0x10/0x10 enable_drhd_fault_handling+0x151/0x180 cpuhp_invoke_callback+0x1df/0x990 cpuhp_thread_fun+0x1ea/0x2c0 smpboot_thread_fn+0x1f5/0x2e0 ? __pfx_smpboot_thread_fn+0x10/0x10 kthread+0x12a/0x2d0 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x4a/0x60 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 </TASK> Holding the lock in enable_drhd_fault_handling() triggers a lockdep splat about a possible deadlock between dmar_global_lock and cpu_hotplug_lock. This is avoided by not holding dmar_global_lock when calling iommu_device_register(), which initiates the device probe process.
CVE-2025-21766 1 Linux 1 Linux Kernel 2026-10-15 8.1 High
In the Linux kernel, the following vulnerability has been resolved: ipv4: use RCU protection in __ip_rt_update_pmtu() __ip_rt_update_pmtu() must use RCU protection to make sure the net structure it reads does not disappear.
CVE-2024-58240 2 Debian, Linux 2 Debian Linux, Linux Kernel 2026-10-15 9.8 Critical
In the Linux kernel, the following vulnerability has been resolved: tls: separate no-async decryption request handling from async If we're not doing async, the handling is much simpler. There's no reference counting, we just need to wait for the completion to wake us up and return its result. We should preferably also use a separate crypto_wait. I'm not seeing a UAF as I did in the past, I think aec7961916f3 ("tls: fix race between async notify and socket close") took care of it. This will make the next fix easier.
CVE-2024-58239 1 Linux 1 Linux Kernel 2026-10-15 8.2 High
In the Linux kernel, the following vulnerability has been resolved: tls: stop recv() if initial process_rx_list gave us non-DATA If we have a non-DATA record on the rx_list and another record of the same type still on the queue, we will end up merging them: - process_rx_list copies the non-DATA record - we start the loop and process the first available record since it's of the same type - we break out of the loop since the record was not DATA Just check the record type and jump to the end in case process_rx_list did some work.
CVE-2024-57875 1 Linux 1 Linux Kernel 2026-10-15 7.8 High
In the Linux kernel, the following vulnerability has been resolved: block: RCU protect disk->conv_zones_bitmap Ensure that a disk revalidation changing the conventional zones bitmap of a disk does not cause invalid memory references when using the disk_zone_is_conv() helper by RCU protecting the disk->conv_zones_bitmap pointer. disk_zone_is_conv() is modified to operate under the RCU read lock and the function disk_set_conv_zones_bitmap() is added to update a disk conv_zones_bitmap pointer using rcu_replace_pointer() with the disk zone_wplugs_lock spinlock held. disk_free_zone_resources() is modified to call disk_update_zone_resources() with a NULL bitmap pointer to free the disk conv_zones_bitmap. disk_set_conv_zones_bitmap() is also used in disk_update_zone_resources() to set the new (revalidated) bitmap and free the old one.
CVE-2024-57849 1 Linux 1 Linux Kernel 2026-10-15 7.8 High
In the Linux kernel, the following vulnerability has been resolved: s390/cpum_sf: Handle CPU hotplug remove during sampling CPU hotplug remove handling triggers the following function call sequence: CPUHP_AP_PERF_S390_SF_ONLINE --> s390_pmu_sf_offline_cpu() ... CPUHP_AP_PERF_ONLINE --> perf_event_exit_cpu() The s390 CPUMF sampling CPU hotplug handler invokes: s390_pmu_sf_offline_cpu() +--> cpusf_pmu_setup() +--> setup_pmc_cpu() +--> deallocate_buffers() This function de-allocates all sampling data buffers (SDBs) allocated for that CPU at event initialization. It also clears the PMU_F_RESERVED bit. The CPU is gone and can not be sampled. With the event still being active on the removed CPU, the CPU event hotplug support in kernel performance subsystem triggers the following function calls on the removed CPU: perf_event_exit_cpu() +--> perf_event_exit_cpu_context() +--> __perf_event_exit_context() +--> __perf_remove_from_context() +--> event_sched_out() +--> cpumsf_pmu_del() +--> cpumsf_pmu_stop() +--> hw_perf_event_update() to stop and remove the event. During removal of the event, the sampling device driver tries to read out the remaining samples from the sample data buffers (SDBs). But they have already been freed (and may have been re-assigned). This may lead to a use after free situation in which case the samples are most likely invalid. In the best case the memory has not been reassigned and still contains valid data. Remedy this situation and check if the CPU is still in reserved state (bit PMU_F_RESERVED set). In this case the SDBs have not been released an contain valid data. This is always the case when the event is removed (and no CPU hotplug off occured). If the PMU_F_RESERVED bit is not set, the SDB buffers are gone.
CVE-2024-57791 1 Linux 1 Linux Kernel 2026-10-15 7.5 High
In the Linux kernel, the following vulnerability has been resolved: net/smc: check return value of sock_recvmsg when draining clc data When receiving clc msg, the field length in smc_clc_msg_hdr indicates the length of msg should be received from network and the value should not be fully trusted as it is from the network. Once the value of length exceeds the value of buflen in function smc_clc_wait_msg it may run into deadloop when trying to drain the remaining data exceeding buflen. This patch checks the return value of sock_recvmsg when draining data in case of deadloop in draining.
CVE-2024-56664 2 Linux, Redhat 2 Linux Kernel, Enterprise Linux 2026-10-15 7.8 High
In the Linux kernel, the following vulnerability has been resolved: bpf, sockmap: Fix race between element replace and close() Element replace (with a socket different from the one stored) may race with socket's close() link popping & unlinking. __sock_map_delete() unconditionally unrefs the (wrong) element: // set map[0] = s0 map_update_elem(map, 0, s0) // drop fd of s0 close(s0) sock_map_close() lock_sock(sk) (s0!) sock_map_remove_links(sk) link = sk_psock_link_pop() sock_map_unlink(sk, link) sock_map_delete_from_link // replace map[0] with s1 map_update_elem(map, 0, s1) sock_map_update_elem (s1!) lock_sock(sk) sock_map_update_common psock = sk_psock(sk) spin_lock(&stab->lock) osk = stab->sks[idx] sock_map_add_link(..., &stab->sks[idx]) sock_map_unref(osk, &stab->sks[idx]) psock = sk_psock(osk) sk_psock_put(sk, psock) if (refcount_dec_and_test(&psock)) sk_psock_drop(sk, psock) spin_unlock(&stab->lock) unlock_sock(sk) __sock_map_delete spin_lock(&stab->lock) sk = *psk // s1 replaced s0; sk == s1 if (!sk_test || sk_test == sk) // sk_test (s0) != sk (s1); no branch sk = xchg(psk, NULL) if (sk) sock_map_unref(sk, psk) // unref s1; sks[idx] will dangle psock = sk_psock(sk) sk_psock_put(sk, psock) if (refcount_dec_and_test()) sk_psock_drop(sk, psock) spin_unlock(&stab->lock) release_sock(sk) Then close(map) enqueues bpf_map_free_deferred, which finally calls sock_map_free(). This results in some refcount_t warnings along with a KASAN splat [1]. Fix __sock_map_delete(), do not allow sock_map_unref() on elements that may have been replaced. [1]: BUG: KASAN: slab-use-after-free in sock_map_free+0x10e/0x330 Write of size 4 at addr ffff88811f5b9100 by task kworker/u64:12/1063 CPU: 14 UID: 0 PID: 1063 Comm: kworker/u64:12 Not tainted 6.12.0+ #125 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.16.3-1-1 04/01/2014 Workqueue: events_unbound bpf_map_free_deferred Call Trace: <TASK> dump_stack_lvl+0x68/0x90 print_report+0x174/0x4f6 kasan_report+0xb9/0x190 kasan_check_range+0x10f/0x1e0 sock_map_free+0x10e/0x330 bpf_map_free_deferred+0x173/0x320 process_one_work+0x846/0x1420 worker_thread+0x5b3/0xf80 kthread+0x29e/0x360 ret_from_fork+0x2d/0x70 ret_from_fork_asm+0x1a/0x30 </TASK> Allocated by task 1202: kasan_save_stack+0x1e/0x40 kasan_save_track+0x10/0x30 __kasan_slab_alloc+0x85/0x90 kmem_cache_alloc_noprof+0x131/0x450 sk_prot_alloc+0x5b/0x220 sk_alloc+0x2c/0x870 unix_create1+0x88/0x8a0 unix_create+0xc5/0x180 __sock_create+0x241/0x650 __sys_socketpair+0x1ce/0x420 __x64_sys_socketpair+0x92/0x100 do_syscall_64+0x93/0x180 entry_SYSCALL_64_after_hwframe+0x76/0x7e Freed by task 46: kasan_save_stack+0x1e/0x40 kasan_save_track+0x10/0x30 kasan_save_free_info+0x37/0x60 __kasan_slab_free+0x4b/0x70 kmem_cache_free+0x1a1/0x590 __sk_destruct+0x388/0x5a0 sk_psock_destroy+0x73e/0xa50 process_one_work+0x846/0x1420 worker_thread+0x5b3/0xf80 kthread+0x29e/0x360 ret_from_fork+0x2d/0x70 ret_from_fork_asm+0x1a/0x30 The bu ---truncated---
CVE-2024-56637 1 Linux 1 Linux Kernel 2026-10-15 7.3 High
In the Linux kernel, the following vulnerability has been resolved: netfilter: ipset: Hold module reference while requesting a module User space may unload ip_set.ko while it is itself requesting a set type backend module, leading to a kernel crash. The race condition may be provoked by inserting an mdelay() right after the nfnl_unlock() call.
CVE-2024-56624 1 Linux 1 Linux Kernel 2026-10-15 7.8 High
In the Linux kernel, the following vulnerability has been resolved: iommufd: Fix out_fput in iommufd_fault_alloc() As fput() calls the file->f_op->release op, where fault obj and ictx are getting released, there is no need to release these two after fput() one more time, which would result in imbalanced refcounts: refcount_t: decrement hit 0; leaking memory. WARNING: CPU: 48 PID: 2369 at lib/refcount.c:31 refcount_warn_saturate+0x60/0x230 Call trace: refcount_warn_saturate+0x60/0x230 (P) refcount_warn_saturate+0x60/0x230 (L) iommufd_fault_fops_release+0x9c/0xe0 [iommufd] ... VFS: Close: file count is 0 (f_op=iommufd_fops [iommufd]) WARNING: CPU: 48 PID: 2369 at fs/open.c:1507 filp_flush+0x3c/0xf0 Call trace: filp_flush+0x3c/0xf0 (P) filp_flush+0x3c/0xf0 (L) __arm64_sys_close+0x34/0x98 ... imbalanced put on file reference count WARNING: CPU: 48 PID: 2369 at fs/file.c:74 __file_ref_put+0x100/0x138 Call trace: __file_ref_put+0x100/0x138 (P) __file_ref_put+0x100/0x138 (L) __fput_sync+0x4c/0xd0 Drop those two lines to fix the warnings above.
CVE-2024-53138 1 Linux 1 Linux Kernel 2026-10-15 9.8 Critical
In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: kTLS, Fix incorrect page refcounting The kTLS tx handling code is using a mix of get_page() and page_ref_inc() APIs to increment the page reference. But on the release path (mlx5e_ktls_tx_handle_resync_dump_comp()), only put_page() is used. This is an issue when using pages from large folios: the get_page() references are stored on the folio page while the page_ref_inc() references are stored directly in the given page. On release the folio page will be dereferenced too many times. This was found while doing kTLS testing with sendfile() + ZC when the served file was read from NFS on a kernel with NFS large folios support (commit 49b29a573da8 ("nfs: add support for large folios")).
CVE-2024-53125 1 Linux 1 Linux Kernel 2026-10-15 7.8 High
In the Linux kernel, the following vulnerability has been resolved: bpf: sync_linked_regs() must preserve subreg_def Range propagation must not affect subreg_def marks, otherwise the following example is rewritten by verifier incorrectly when BPF_F_TEST_RND_HI32 flag is set: 0: call bpf_ktime_get_ns call bpf_ktime_get_ns 1: r0 &= 0x7fffffff after verifier r0 &= 0x7fffffff 2: w1 = w0 rewrites w1 = w0 3: if w0 < 10 goto +0 --------------> r11 = 0x2f5674a6 (r) 4: r1 >>= 32 r11 <<= 32 (r) 5: r0 = r1 r1 |= r11 (r) 6: exit; if w0 < 0xa goto pc+0 r1 >>= 32 r0 = r1 exit (or zero extension of w1 at (2) is missing for architectures that require zero extension for upper register half). The following happens w/o this patch: - r0 is marked as not a subreg at (0); - w1 is marked as subreg at (2); - w1 subreg_def is overridden at (3) by copy_register_state(); - w1 is read at (5) but mark_insn_zext() does not mark (2) for zero extension, because w1 subreg_def is not set; - because of BPF_F_TEST_RND_HI32 flag verifier inserts random value for hi32 bits of (2) (marked (r)); - this random value is read at (5).