In the Linux kernel, the following vulnerability has been resolved:

fscache: Fix oops due to race with cookie_lru and use_cookie

If a cookie expires from the LRU and the LRU_DISCARD flag is set, but the state machine has not run yet, it's possible another thread can call fscache_use_cookie and begin to use it.

When the cookie_worker finally runs, it will see the LRU_DISCARD flag set, transition the cookie->state to LRU_DISCARDING, which will then withdraw the cookie. Once the cookie is withdrawn the object is removed the below oops will occur because the object associated with the cookie is now NULL.

Fix the oops by clearing the LRU_DISCARD bit if another thread uses the cookie before the cookie_worker runs.

BUG: kernel NULL pointer dereference, address: 0000000000000008 ... CPU: 31 PID: 44773 Comm: kworker/u130:1 Tainted: G E 6.0.0-5.dneg.x86_64 #1 Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022 Workqueue: events_unbound netfs_rreq_write_to_cache_work [netfs] RIP: 0010:cachefiles_prepare_write+0x28/0x90 [cachefiles] ... Call Trace: netfs_rreq_write_to_cache_work+0x11c/0x320 [netfs] process_one_work+0x217/0x3e0 worker_thread+0x4a/0x3b0 kthread+0xd6/0x100

In the Linux kernel, the following vulnerability has been resolved:

fscache: Fix oops due to race with cookie_lru and use_cookie

If a cookie expires from the LRU and the LRU_DISCARD flag is set, but the state machine has not run yet, it's possible another thread can call fscache_use_cookie and begin to use it.

When the cookie_worker finally runs, it will see the LRU_DISCARD flag set, transition the cookie->state to LRU_DISCARDING, which will then withdraw the cookie. Once the cookie is withdrawn the object is removed the below oops will occur because the object associated with the cookie is now NULL.

Fix the oops by clearing the LRU_DISCARD bit if another thread uses the cookie before the cookie_worker runs.

BUG: kernel NULL pointer dereference, address: 0000000000000008 ... CPU: 31 PID: 44773 Comm: kworker/u130:1 Tainted: G E 6.0.0-5.dneg.x86_64 #1 Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022 Workqueue: events_unbound netfs_rreq_write_to_cache_work [netfs] RIP: 0010:cachefiles_prepare_write+0x28/0x90 [cachefiles] ... Call Trace: netfs_rreq_write_to_cache_work+0x11c/0x320 [netfs] process_one_work+0x217/0x3e0 worker_thread+0x4a/0x3b0 kthread+0xd6/0x100

kernel: xen-netfront: Fix NULL sring after live migration kernel: fscache: Fix oops due to race with cookie_lru and use_cookie kernel: tracing: Free buffers when a used dynamic event is removed kernel: net: tun: Fix use-after-free in tun_detach() kernel: hwmon: (ibmpex) Fix possible UAF when ibmpex_register_bmc() fails kernel: erofs/zmap.c: Fix incorrect offset calculation kernel: arm64/mm: fix incorrect file_map_count for non-leaf pmd/pud kernel: s390: avoid using global register for current_stack_pointer kernel: erofs: fix missing xas_retry() in fscache mode kernel: rpmsg: qcom_smd: Fix refcount leak in qcom_smd_parse_edge kernel: remoteproc: k3-r5: Fix refcount leak in k3_r5_cluster_of_init kernel: of: check previous kernel's ima-kexec-buffer against memory bounds kernel: coresight: Clear the connection field properly kernel: Linux kernel: Denial of Service in coresight: trbe kernel: rpmsg: char: Avoid double destroy of default endpoint kernel: coresight: cti: Fix hang in cti_disable_hw() kernel: lib/fonts: fix undefined behavior in bit shift for get_default_font kernel: Kernel: Denial of Service in pci_endpoint_test due to zero-length DMA mapping kernel: Linux kernel: Denial of Service in erofs due to memory leak kernel: erofs: fix missing unmap if z_erofs_get_extent_compressedlen() fails kernel: pipe: wakeup wr_wait after setting max_usage kernel: ntb: intel: Fix the NULL vs IS_ERR() bug for debugfs_create_dir() kernel: qed/qed_sriov: guard against NULL derefs from qed_…

Security update for the Linux Kernel

Affected: Ubuntu:16.04:LTS: linux-hwe-edge, Ubuntu:18.04:LTS: linux-aws-5.0, Ubuntu:18.04:LTS: linux-aws-5.3, Ubuntu:18.04:LTS: linux-azure, Ubuntu:18.04:LTS: linux-azure-5.3, Ubuntu:18.04:LTS: linux-azure-edge, Ubuntu:18.04:LTS: linux-gcp, Ubuntu:18.04:LTS: linux-gcp-5.3, Ubuntu:18.04:LTS: linux-gke-4.15, Ubuntu:18.04:LTS: linux-gke-5.4 and 66 more

In the Linux kernel, the following vulnerability has been resolved: fscache: Fix oops due to race with cookie_lru and use_cookie If a cookie expires from the LRU and the LRU_DISCARD flag is set, but the state machine has not run yet, it's possible another thread can call fscache_use_cookie and begin to use it. When the cookie_worker finally runs, it will see the LRU_DISCARD flag set, transition the cookie->state to LRU_DISCARDING, which will then withdraw the cookie. Once the cookie is withdrawn the object is removed the below oops will occur because the object associated with the cookie is now NULL. Fix the oops by clearing the LRU_DISCARD bit if another thread uses the cookie before the cookie_worker runs. BUG: kernel NULL pointer dereference, address: 0000000000000008 ... CPU: 31 PID: 44773 Comm: kworker/u130:1 Tainted: G E 6.0.0-5.dneg.x86_64 #1 Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022 Workqueue: events_unbound netfs_rreq_write_to_cache_work [netfs] RIP: 0010:cachefiles_prepare_write+0x28/0x90 [cachefiles] ... Call Trace: netfs_rreq_write_to_cache_work+0x11c/0x320 [netfs] process_one_work+0x217/0x3e0 worker_thread+0x4a/0x3b0 kthread+0xd6/0x100

Ein Angreifer kann mehrere Schwachstellen in Linux Kernel ausnutzen, um einen Denial of Service Angriff durchzuführen oder andere, nicht näher bekannte Auswirkungen zu erzielen..