CVE-2026-98020 pds_core: fix cmd_regs access racing BAR unmap on reset
A race condition in the pds_core driver allows unmapping memory during firmware updates, potentially causing a kernel crash or arbitrary code execution.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98020?
CVE-2026-98020 is a vulnerability in Linux, published on 25 Sep 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:
pds_core: fix cmd_regs access racing BAR unmap on reset
pdsc_reset_prepare() and pdsc_reset_done()'s pdsc_map_bars() error path clear/iounmap cmd_regs without devcmd_lock, and pdsc_legacy_firmware_update()'s download loop derefs cmd_regs after dropping and retaking the lock without re-checking. An FLR concurrent with a devlink flash can unmap cmd_regs under an in-flight devcmd, causing a NULL deref or a write to unmapped MMIO.
Take devcmd_lock across the BAR unmap/remap, and re-check cmd_regs in the download loop. Only the PF maps cmd_regs and runs devcmd, so skip the unmap on a VF, as pdsc_remove() and pdsc_reset_done() already do.
A reset that completes entirely within the unlocked window is not a correctness problem for the image: the device clears its update session, so a resumed download is rejected, and it verifies the staged image before writing a flash slot, reporting PDS_RC_BAD_FW rather than activating it.
pdsc_unmap_bars() also clears info_regs, intr_status and intr_ctrl. The interrupt and start/stop readers of those are quiesced before the unmap by pdsc_fw_down(), which frees the interrupts and tears down the queues. The debugfs readers are not, since those files outlive a reset; that is pre-existing and out of scope here.
Which versions are affected by CVE-2026-98020?
How do I fix CVE-2026-98020?
Apply the vendor's patch.
Is CVE-2026-98020 being exploited?
There is no known exploitation of CVE-2026-98020 in the wild and no public exploit code.
Sources
Also known as AZL-104229, BELL-CVE-2026-98020, DEBIAN-CVE-2026-98020, GHSA-qm2m-cwg6-99v6, UBUNTU-CVE-2026-98020.