CVE-2026-31703 — writeback: Fix use after free in inode_switch_wbs_work_fn()

Affected: Linux, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9

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

writeback: Fix use after free in inode_switch_wbs_work_fn()

inode_switch_wbs_work_fn() has a loop like:

wb_get(new_wb); while (1) { list = llist_del_all(&new_wb->switch_wbs_ctxs); /* Nothing to do? */ if (!list) break; ... process the items ... }

Now adding of items to the list looks like:

wb_queue_isw() if (llist_add(&isw->list, &wb->switch_wbs_ctxs)) queue_work(isw_wq, &wb->switch_work);

Because inode_switch_wbs_work_fn() loops when processing isw items, it can happen that wb->switch_work is pending while wb->switch_wbs_ctxs is empty. This is a problem because in that case wb can get freed (no isw items -> no wb reference) while the work is still pending causing use-after-free issues.

We cannot just fix this by cancelling work when freeing wb because that could still trigger problematic 0 -> 1 transitions on wb refcount due to wb_get() in inode_switch_wbs_work_fn(). It could be all handled with more careful code but that seems unnecessarily complex so let's avoid that until it is proven that the looping actually brings practical benefit. Just remove the loop from inode_switch_wbs_work_fn() instead. That way when wb_queue_isw() queues work, we are guaranteed we have added the first item to wb->switch_wbs_ctxs and nobody is going to remove it (and drop the wb reference it holds) until the queued work runs.

USN-8488-1 — linux, linux-aws, linux-gcp, linux-ibm, linux-oracle, linux-realtime vulnerabilities

Affected: Ubuntu:26.04:LTS: linux, Ubuntu:26.04:LTS: linux-aws, Ubuntu:26.04:LTS: linux-gcp, Ubuntu:26.04:LTS: linux-ibm, Ubuntu:26.04:LTS: linux-oracle, Ubuntu:26.04:LTS: linux-realtime

It was discovered that some AMD processors did not properly clear data in the floating point divider unit during speculative execution. A local attacker could use this to expose sensitive information. (CVE-2025-54505)

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - ARM64 architecture; - x86 architecture; - Block layer subsystem; - Cryptographic API; - Rados block device (RBD) driver; - Compressed RAM block device driver; - Character device driver; - TPM device driver; - Hardware crypto device drivers; - EDAC drivers; - GPU drivers; - Greybus drivers; - HID subsystem; - Microsoft Hyper-V drivers; - Hardware monitoring drivers; - I2C subsystem; - IIO subsystem; - InfiniBand drivers; - Input Device core drivers; - LED subsystem; - Multiple devices driver; - Media drivers; - IBM Advanced System Management driver; - MTD block device drivers; - Network drivers; - Microsoft Azure Network Adapter (MANA) driver; - NTB driver; - NVME drivers; - Device tree and open firmware driver; - PCI subsystem; - Remote Processor subsystem; - SCSI subsystem; - SPI subsystem; - Realtek RTL8723BS SDIO drivers; - SM750 framebuffer staging driver; - Thermal drivers; - USB Gadget drivers; - USB over IP driver; - VFIO drivers; - Framebuffer layer; - 9P distributed file system; - AFS file…

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CVE-2026-31703 — writeback: Fix use after free in inode_switch_wbs_work_fn()

USN-8488-1 — linux, linux-aws, linux-gcp, linux-ibm, linux-oracle, linux-realtime vulnerabilities