CVE-2026-74734 firewire: ohci: fix NULL pointer dereference in ar_context_release
A local attacker can cause a kernel crash via a NULL pointer dereference in the FireWire OHCI driver during device probe failure.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74734?
CVE-2026-74734 is a vulnerability in Linux, published on 26 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
firewire: ohci: fix NULL pointer dereference in ar_context_release
During the error handling path of the driver's probe function, a NULL pointer dereference can occur in ar_context_release().
When pci_probe() fails early (e.g., if pcim_enable_device() or MMIO mapping fails), the devres cleanup mechanism invokes release_ohci(). This function unconditionally calls ar_context_release() to clean up the asynchronous receive contexts. However, if ar_context_init() was not yet called, ctx->ohci remains NULL (as the fw_ohci structure is zero-initialized by devres_alloc()).
ar_context_release() immediately dereferences ctx->ohci to get the dev pointer before checking if the context was actually initialized, leading to a crash:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] RIP: 0010:ar_context_release+0x3f/0x380 drivers/firewire/ohci.c:543 Call Trace: release_ohci+0x3f/0x60 drivers/firewire/ohci.c:3567 release_nodes drivers/base/devres.c:546 [inline] devres_release_all+0x1a8/0x260 drivers/base/devres.c:576 device_unbind_cleanup drivers/base/dd.c:597 [inline] really_probe+0x451/0xae0 drivers/base/dd.c:772
To fix this, move the assignment of the dev pointer after the !ctx->buffer check. If ctx->buffer is NULL, it indicates that the context was never successfully initialized and there is nothing to release, safely avoiding the dereference of the uninitialized ctx->ohci pointer.
Which versions are affected by CVE-2026-74734?
How do I fix CVE-2026-74734?
Apply the vendor's patch.
Is CVE-2026-74734 being exploited?
There is no known exploitation of CVE-2026-74734 in the wild and no public exploit code.
Sources
Also known as AZL-97832, BELL-CVE-2026-74734, DEBIAN-CVE-2026-74734, GHSA-q794-m3rx-76gj, UBUNTU-CVE-2026-74734.