Displaying 2 results from an estimated 2 matches for "vm_min_address".
2009 Sep 15
4
Protecting against kernel NULL-pointer derefs
...map pages at address 0x0 (and a bit beyond),
it is possible to make such NULL-pointer deref bugs mere DoS'es instead
of code execution bugs. Linux has implemented such a protection for a
long while now, by disallowing page mappings on 0x0 - 0xffff.
On FreeBSD, it appears that simply bumping up VM_MIN_ADDRESS to 65536
downgrades a whole class of code execution vulnerabilities to DoS
vulnerabilities. I've raised that #define to 65536 on a 6.4-RELEASE i386
VM. This made at least the mmap() method to map at 0x0 fail.
So:
- How do you feel about disallowing such mappings to protect against
NULL-pointer...
2003 Aug 12
2
panic with today's stable
..., end);
2200 vm_map_unlock(map);
2201
2202 if (map == kmem_map || map == mb_map)
2203 splx(s);
(kgdb) up
#13 0xc0159c3d in exit1 (p=0xe8a89ea0, rv=1054720) at
/usr/src/sys/kern/kern_exit.c:226
226 (void) vm_map_remove(&vm->vm_map, VM_MIN_ADDRESS,
(kgdb) list
221 if (--vm->vm_refcnt == 0) {
222 if (vm->vm_shm)
223 shmexit(p);
224 pmap_remove_pages(vmspace_pmap(vm), VM_MIN_ADDRESS,
225 VM_MAXUSER_ADDRESS);
226 (vo...