Description
In the Linux kernel, the following vulnerability has been resolved:
parport: Fix race between port and client registration
The parport subsystem registers port devices before they are fully
initialised, resulting in a race condition where client drivers such
as lp can attach to ports that are not completely initialised or even
being torn down.
When the port and client drivers are built as modules and loaded
around the same time during boot, this occasionally results in a
crash. I was able to make this happen reliably in a VM with a
PC-style parallel port by patching parport_pc to fail probing:
> --- a/drivers/parport/parport_pc.c
> +++ b/drivers/parport/parport_pc.c
> @@ -2069,7 +2069,7 @@ static struct parport *__parport_pc_probe_port(unsigned long int base,
> if (!p)
> goto out3;
>
> - base_res = request_region(base, 3, p->name);
> + base_res = NULL;
> if (!base_res)
> goto out4;
>
and then running:
while true; do
modprobe lp & modprobe parport_pc
wait
rmmod lp parport_pc
done
for a few seconds.
In the long term I think port registration should be changed to put
the call to device_add() inside parport_announce_port(), but since the
latter currently cannot fail this will require changing all port
drivers.
For now, add a flag to indicate whether a port has been "announced"
and only try to attach client drivers to ports when the flag is set.
parport: Fix race between port and client registration
The parport subsystem registers port devices before they are fully
initialised, resulting in a race condition where client drivers such
as lp can attach to ports that are not completely initialised or even
being torn down.
When the port and client drivers are built as modules and loaded
around the same time during boot, this occasionally results in a
crash. I was able to make this happen reliably in a VM with a
PC-style parallel port by patching parport_pc to fail probing:
> --- a/drivers/parport/parport_pc.c
> +++ b/drivers/parport/parport_pc.c
> @@ -2069,7 +2069,7 @@ static struct parport *__parport_pc_probe_port(unsigned long int base,
> if (!p)
> goto out3;
>
> - base_res = request_region(base, 3, p->name);
> + base_res = NULL;
> if (!base_res)
> goto out4;
>
and then running:
while true; do
modprobe lp & modprobe parport_pc
wait
rmmod lp parport_pc
done
for a few seconds.
In the long term I think port registration should be changed to put
the call to device_add() inside parport_announce_port(), but since the
latter currently cannot fail this will require changing all port
drivers.
For now, add a flag to indicate whether a port has been "announced"
and only try to attach client drivers to ports when the flag is set.
Published:
2026-07-19
Score:
n/a
EPSS:
n/a
KEV:
No
Impact:
n/a
Action:
n/a
Analysis
No analysis available yet.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
|||||||||||||||||||||||||||||||||
| Linux | Linux | affected |
|
No data.
No data.
No data available yet.
Remediation
No remediation available yet.
Tracking
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Advisories
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References
History
Sun, 19 Jul 2026 15:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: parport: Fix race between port and client registration The parport subsystem registers port devices before they are fully initialised, resulting in a race condition where client drivers such as lp can attach to ports that are not completely initialised or even being torn down. When the port and client drivers are built as modules and loaded around the same time during boot, this occasionally results in a crash. I was able to make this happen reliably in a VM with a PC-style parallel port by patching parport_pc to fail probing: > --- a/drivers/parport/parport_pc.c > +++ b/drivers/parport/parport_pc.c > @@ -2069,7 +2069,7 @@ static struct parport *__parport_pc_probe_port(unsigned long int base, > if (!p) > goto out3; > > - base_res = request_region(base, 3, p->name); > + base_res = NULL; > if (!base_res) > goto out4; > and then running: while true; do modprobe lp & modprobe parport_pc wait rmmod lp parport_pc done for a few seconds. In the long term I think port registration should be changed to put the call to device_add() inside parport_announce_port(), but since the latter currently cannot fail this will require changing all port drivers. For now, add a flag to indicate whether a port has been "announced" and only try to attach client drivers to ports when the flag is set. | |
| Title | parport: Fix race between port and client registration | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-07-19T14:55:37.717Z
Reserved: 2026-07-19T07:54:57.022Z
Link: CVE-2026-63942
Vulnrichment
No data.
NVD
No data.
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.