Overview
About vulnerability
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 existent vm area. … }
Fix this breakage by updating ipcomp_scrtches with NULL when scratches is freed
Details
- Affected product:
- AlmaLinux 9.2 ESU , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , TuxCare 9.6 ESU
- Affected packages:
- kernel @ 4.18.0 (+4 more)
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 existent vm area. … }
Fix this breakage by updating ipcomp_scrtches with NULL when scratches is freed