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CVE-2026-64141 — ksmbd: fix null pointer dereference in compare_guid_key()

Affected: Linux

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

ksmbd: fix null pointer dereference in compare_guid_key()

session_fd_check() walks the per-inode m_op_list during durable-handle session teardown and sets op->conn = NULL for every opinfo whose conn matched the closing session's connection. The matching opinfo, however, stays linked in its per-ClientGuid lease_table_list entry's lb->lease_list because destroy_lease_table() only runs on full TCP-connection teardown, not on SESSION_LOGOFF.

If the same TCP connection then negotiates a fresh session with the same ClientGuid (ClientGuid is bound to NEGOTIATE, not the session, and is unchanged across LOGOFF + SETUP) and issues a SMB2 CREATE with a lease context on a different inode, find_same_lease_key() walks lb->lease_list, reaches the stale opinfo, and calls compare_guid_key(), which unconditionally dereferences opinfo->conn->ClientGUID. The conn pointer is NULL and the kernel panics.

Reproducer requires only a successful SMB2 SESSION_SETUP and a share configured with 'durable handles = yes'. KASAN report on mainline 70390501d194:

general protection fault, probably for non-canonical address 0xdffffc0000000069: 0000 [#1] SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000348-0x000000000000034f] Workqueue: ksmbd-io handle_ksmbd_work RIP: 0010:bcmp+0x5b/0x230 Call Trace: compare_guid_key+0x4b/0xd0 find_same_lease_key+0x324/0x690 smb2_open+0x6aea/0x8e60 handle_ksmbd_work+0x796…

USN-8593-1 — linux-ibm, linux-oracle vulnerabilities

Affected: Ubuntu:26.04:LTS: linux-ibm, Ubuntu:26.04:LTS: linux-oracle

It was discovered that some AMD Zen 2 processors did not properly isolate shared resources in the operation cache. A local attacker could possibly use this issue to corrupt instructions executed at a higher privilege level, resulting in privilege escalation. (CVE-2025-54518)

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: - x86 platform drivers; - PSP security protocol; - ARM32 architecture; - ARM64 architecture; - MIPS architecture; - PowerPC architecture; - RISC-V architecture; - S390 architecture; - User-Mode Linux (UML); - x86 architecture; - Block layer subsystem; - Cryptographic API; - Intel NPU Driver; - Compute Acceleration Framework; - ACPI drivers; - Auxiliary display drivers; - Drivers core; - DRBD Distributed Replicated Block Device drivers; - Rados block device (RBD) driver; - Ublk userspace block driver; - Compressed RAM block device driver; - Bluetooth drivers; - Bus devices; - Character device driver; - Clock framework and drivers; - CPU frequency scaling framework; - Hardware crypto device drivers; - Buffer Sharing and Synchronization framework; - DPLL subsystem; - EDAC drivers; - Arm Firmware Framework for ARMv8-A(FFA); - EFI core; - FWCTL subsystem; - GPIO subsystem; - GPU drivers; - HID subsystem; - Hardware monitoring drivers; - I2C subsystem; - I…