CVE-2026-74363 — bpf: fix UAF by restoring RCU-delayed inode freeing in bpffs

Affected: Linux

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

bpf: fix UAF by restoring RCU-delayed inode freeing in bpffs

commit 4f375ade6aa9 ("bpf: Avoid RCU context warning when unpinning htab with internal structs") moved inode cleanup from ->free_inode() into ->destroy_inode() to avoid sleeping in RCU context when calling bpf_any_put(). However this removed the RCU delay on freeing the inode itself and the cached symlink body (i_link), both of which can be accessed by RCU pathwalk (pick_link, may_lookup etc.).

This causes a use-after-free when a concurrent unlinkat() drops the last inode reference and destroy_inode() frees the inode immediately, while another task is still walking the path in RCU mode and reads inode->i_opflags (offset +2) inside current_time() -> is_mgtime().

KASAN reports: BUG: KASAN: slab-use-after-free in is_mgtime include/linux/fs.h:2313 Read of size 2 at addr ffff8880407e4282 (offset +2 = i_opflags)

The rules (per Al Viro): ->destroy_inode() called immediately, can sleep, use for blocking cleanup e.g. bpf_any_put() ->free_inode() called after RCU grace period, use for freeing inode and anything RCU-accessible e.g. i_link

Fix: split the two concerns properly: - keep bpf_any_put() in bpf_destroy_inode() since it is blocking and needs to run promptly - introduce bpf_free_inode() to handle kfree(i_link) and free_inode_nonrcu() with proper RCU delay, preventing the UAF

USN-8875-1 — linux, linux-aws, linux-aws-5.15, linux-aws-fips, linux-azure, linux-azure-5.15, linux-azure-fde-5.15, linux-azure-fips…

Affected: Ubuntu:Pro:20.04:LTS: linux-aws-5.15, Ubuntu:Pro:20.04:LTS: linux-azure-5.15, Ubuntu:Pro:20.04:LTS: linux-azure-fde-5.15, Ubuntu:Pro:20.04:LTS: linux-hwe-5.15, Ubuntu:Pro:20.04:LTS: linux-ibm-5.15, Ubuntu:Pro:20.04:LTS: linux-intel-iotg-5.15, Ubuntu:Pro:20.04:LTS: linux-lowlatency-hwe-5.15, Ubuntu:22.04:LTS: linux, Ubuntu:22.04:LTS: linux-aws, Ubuntu:22.04:LTS: linux-azure and 13 more

It was discovered that the i.MX clock driver in the Linux kernel did not properly handle certain memory allocation failure conditions, leading to a null pointer dereference vulnerability. A local attacker could possibly use this to cause a denial of service (system crash). (CVE-2022-3114)

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: - User-space API (UAPI); - ARM32 architecture; - ARM64 architecture; - MIPS architecture; - PowerPC architecture; - RISC-V architecture; - User-Mode Linux (UML); - x86 architecture; - Block layer subsystem; - Cryptographic API; - ACPI drivers; - Android drivers; - Serial ATA and Parallel ATA drivers; - Drivers core; - DRBD Distributed Replicated Block Device drivers; - Rados block device (RBD) driver; - Bluetooth drivers; - Cdrom driver; - Character device driver; - Hardware random number generator core; - TPM device driver; - Data acquisition framework and drivers; - CPU frequency scaling framework; - Hardware crypto device drivers; - DAX dirext access to differentiated memory framework; - DMA engine subsystem; - FireWire subsystem; - Arm Firmware Framework for ARMv8-A(FFA); - ARM SCMI message protocol; - Intel Stratix 10 firmware drivers; - FPGA Framework; - GPIO subsystem; - GPU drivers; - HID subsystem; - Hardware monitoring drivers; - In…

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CVE-2026-74363 — bpf: fix UAF by restoring RCU-delayed inode freeing in bpffs

USN-8875-1 — linux, linux-aws, linux-aws-5.15, linux-aws-fips, linux-azure, linux-azure-5.15, linux-azure-fde-5.15, linux-azure-fips…