Linux Kernel up to 6.2.15/6.3.2 afs_make_call null pointer dereference

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.2.15/6.3.2 and classified as critical. This impacts the function afs_make_call. Such manipulation leads to null pointer dereference. This vulnerability is referenced as CVE-2023-54195. No exploit is available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.2.15/6.3.2. It has been rated as critical. Affected by this issue is the function afs_make_call. The manipulation with an unknown input leads to a null pointer dereference vulnerability. Using CWE to declare the problem leads to CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. Impacted is availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: rxrpc: Fix timeout of a call that hasn't yet been granted a channel afs_make_call() calls rxrpc_kernel_begin_call() to begin a call (which may get stalled in the background waiting for a connection to become available); it then calls rxrpc_kernel_set_max_life() to set the timeouts - but that starts the call timer so the call timer might then expire before we get a connection assigned - leading to the following oops if the call stalled: BUG: kernel NULL pointer dereference, address: 0000000000000000 ... CPU: 1 PID: 5111 Comm: krxrpcio/0 Not tainted 6.3.0-rc7-build3+ #701 RIP: 0010:rxrpc_alloc_txbuf+0xc0/0x157 ... Call Trace: <TASK> rxrpc_send_ACK+0x50/0x13b rxrpc_input_call_event+0x16a/0x67d rxrpc_io_thread+0x1b6/0x45f ? _raw_spin_unlock_irqrestore+0x1f/0x35 ? rxrpc_input_packet+0x519/0x519 kthread+0xe7/0xef ? kthread_complete_and_exit+0x1b/0x1b ret_from_fork+0x22/0x30 Fix this by noting the timeouts in struct rxrpc_call when the call is created. The timer will be started when the first packet is transmitted. It shouldn't be possible to trigger this directly from userspace through AF_RXRPC as sendmsg() will return EBUSY if the call is in the waiting-for-conn state if it dropped out of the wait due to a signal.

The advisory is available at git.kernel.org. This vulnerability is handled as CVE-2023-54195 since 12/30/2025. The exploitation is known to be difficult. Technical details are known, but there is no available exploit.

Upgrading to version 6.2.16 or 6.3.3 eliminates this vulnerability. Applying the patch 92128a7170a220b5126d09a1c1954a3a8d46cef3/72f4a9f3f447948cf86dffe1c4a4c8a429ab9666/db099c625b13a74d462521a46d98a8ce5b53af5d is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.2.0
• 6.2.1
• 6.2.2
• 6.2.3
• 6.2.4
• 6.2.5
• 6.2.6
• 6.2.7
• 6.2.8
• 6.2.9
• 6.2.10
• 6.2.11
• 6.2.12
• 6.2.13
• 6.2.14
• 6.2.15
• 6.3.0
• 6.3.1
• 6.3.2

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Entryinfo

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