CVE-2022-50569

Technical Description

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

xfrm: Update ipcomp_scratches with NULL when freed

Currently if ipcomp_alloc_scratches() fails to allocate memory

ipcomp_scratches holds obsolete address. So when we try to free the

percpu scratches using ipcomp_free_scratches() it tries to vfree non

existent vm area. Described below:

static void * __percpu *ipcomp_alloc_scratches(void)

{

...

scratches = alloc_percpu(void *);

if (!scratches)

return NULL;

ipcomp_scratches does not know about this allocation failure.

Therefore holding the old obsolete address.

...

}

So when we free,

static void ipcomp_free_scratches(void)

{

...

scratches = ipcomp_scratches;

Assigning obsolete address from ipcomp_scratches

if (!scratches)

return;

for_each_possible_cpu(i)

vfree(*per_cpu_ptr(scratches, i));

Trying to free non existent page, causing warning: trying to vfree

e

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References