Threats Tagged 'cve-2025-39881'

The kernel packages contain the Linux kernel, the core of any Linux operating system. Security Fix(es): * kernel: KVM: x86/hyper-v: Skip non-canonical addresses during PV TLB flush (CVE-2025-38351) * kernel: do_change_type(): refuse to operate on unmounted/not ours mounts (CVE-2025-38498) * kernel: NFS: Fix a race when updating an existing write (CVE-2025-39697) * kernel: kernfs: Fix UAF in polling when open file is released (CVE-2025-39881) * kernel: Bluetooth: hci_event: Fix UAF in hci_acl_create_conn_sync (CVE-2025-39982) * kernel: i40e: fix idx validation in config queues msg (CVE-2025-39971) * kernel: Bluetooth: hci_event: Fix UAF in hci_conn_tx_dequeue (CVE-2025-39983) * kernel: io_uring/waitid: always prune wait queue entry in io_waitid_wait() (CVE-2025-40047) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

A security advisory from Red Hat addresses multiple vulnerabilities in the Linux kernel packages for Red Hat Enterprise Linux 10 and related products. The update fixes issues including race conditions, buffer overflows, use-after-free, and validation errors across various kernel subsystems such as NFS, vsock/virtio, IPv6, ALSA audio, and others. The advisory rates the overall impact as moderate and requires a system reboot after applying the update.

In the Linux kernel, the following vulnerability has been resolved: kernfs: Fix UAF in polling when open file is released A use-after-free (UAF) vulnerability was identified in the PSI (Pressure Stall Information) monitoring mechanism: BUG: KASAN: slab-use-after-free in psi_trigger_poll+0x3c/0x140 Read of size 8 at addr ffff3de3d50bd308 by task systemd/1 psi_trigger_poll+0x3c/0x140 cgroup_pressure_poll+0x70/0xa0 cgroup_file_poll+0x8c/0x100 kernfs_fop_poll+0x11c/0x1c0 ep_item_poll.isra.0+0x188/0x2c0 Allocated by task 1: cgroup_file_open+0x88/0x388 kernfs_fop_open+0x73c/0xaf0 do_dentry_open+0x5fc/0x1200 vfs_open+0xa0/0x3f0 do_open+0x7e8/0xd08 path_openat+0x2fc/0x6b0 do_filp_open+0x174/0x368 Freed by task 8462: cgroup_file_release+0x130/0x1f8 kernfs_drain_open_files+0x17c/0x440 kernfs_drain+0x2dc/0x360 kernfs_show+0x1b8/0x288 cgroup_file_show+0x150/0x268 cgroup_pressure_write+0x1dc/0x340 cgroup_file_write+0x274/0x548 Reproduction Steps: 1. Open test/cpu.pressure and establish epoll monitoring 2. Disable monitoring: echo 0 > test/cgroup.pressure 3. Re-enable monitoring: echo 1 > test/cgroup.pressure The race condition occurs because: 1. When cgroup.pressure is disabled (echo 0 > cgroup.pressure), it: - Releases PSI triggers via cgroup_file_release() - Frees of->priv through kernfs_drain_open_files() 2. While epoll still holds reference to the file and continues polling 3. Re-enabling (echo 1 > cgroup.pressure) accesses freed of->priv epolling disable/enable cgroup.pressure fd=open(cpu.pressure) while(1) ... epoll_wait kernfs_fop_poll kernfs_get_active = true echo 0 > cgroup.pressure ... cgroup_file_show kernfs_show // inactive kn kernfs_drain_open_files cft->release(of); kfree(ctx); ... kernfs_get_active = false echo 1 > cgroup.pressure kernfs_show kernfs_activate_one(kn); kernfs_fop_poll kernfs_get_active = true cgroup_file_poll psi_trigger_poll // UAF ... end: close(fd) To address this issue, introduce kernfs_get_active_of() for kernfs open files to obtain active references. This function will fail if the open file has been released. Replace kernfs_get_active() with kernfs_get_active_of() to prevent further operations on released file descriptors.

In the Linux kernel, the following vulnerability has been resolved: ipv6: sr: Fix MAC comparison to be constant-time To prevent timing attacks, MACs need to be compared in constant time. Use the appropriate helper function for this.

In the Linux kernel, the following vulnerability has been resolved: nfsd: handle get_client_locked() failure in nfsd4_setclientid_confirm() Lei Lu recently reported that nfsd4_setclientid_confirm() did not check the return value from get_client_locked(). a SETCLIENTID_CONFIRM could race with a confirmed client expiring and fail to get a reference. That could later lead to a UAF. Fix this by getting a reference early in the case where there is an extant confirmed client. If that fails then treat it as if there were no confirmed client found at all. In the case where the unconfirmed client is expiring, just fail and return the result from get_client_locked().