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authorMitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>2011-10-31 20:08:13 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2011-10-31 20:30:47 -0400
commitf5252e009d5b87071a919221e4f6624184005368 (patch)
tree4be380e99c468dcb10597c445eb6b801897eafea /mm/vmalloc.c
parent8c5fb8eadde41f67c61a7ac2d3246dab87bf7020 (diff)
mm: avoid null pointer access in vm_struct via /proc/vmallocinfo
The /proc/vmallocinfo shows information about vmalloc allocations in vmlist that is a linklist of vm_struct. It, however, may access pages field of vm_struct where a page was not allocated. This results in a null pointer access and leads to a kernel panic. Why this happens: In __vmalloc_node_range() called from vmalloc(), newly allocated vm_struct is added to vmlist at __get_vm_area_node() and then, some fields of vm_struct such as nr_pages and pages are set at __vmalloc_area_node(). In other words, it is added to vmlist before it is fully initialized. At the same time, when the /proc/vmallocinfo is read, it accesses the pages field of vm_struct according to the nr_pages field at show_numa_info(). Thus, a null pointer access happens. The patch adds the newly allocated vm_struct to the vmlist *after* it is fully initialized. So, it can avoid accessing the pages field with unallocated page when show_numa_info() is called. Signed-off-by: Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: David Rientjes <rientjes@google.com> Cc: Namhyung Kim <namhyung@gmail.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: <stable@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmalloc.c')
-rw-r--r--mm/vmalloc.c65
1 files changed, 48 insertions, 17 deletions
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 5016f19e1661..56faf3163ee2 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1253,18 +1253,22 @@ EXPORT_SYMBOL_GPL(map_vm_area);
1253DEFINE_RWLOCK(vmlist_lock); 1253DEFINE_RWLOCK(vmlist_lock);
1254struct vm_struct *vmlist; 1254struct vm_struct *vmlist;
1255 1255
1256static void insert_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va, 1256static void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va,
1257 unsigned long flags, void *caller) 1257 unsigned long flags, void *caller)
1258{ 1258{
1259 struct vm_struct *tmp, **p;
1260
1261 vm->flags = flags; 1259 vm->flags = flags;
1262 vm->addr = (void *)va->va_start; 1260 vm->addr = (void *)va->va_start;
1263 vm->size = va->va_end - va->va_start; 1261 vm->size = va->va_end - va->va_start;
1264 vm->caller = caller; 1262 vm->caller = caller;
1265 va->private = vm; 1263 va->private = vm;
1266 va->flags |= VM_VM_AREA; 1264 va->flags |= VM_VM_AREA;
1265}
1266
1267static void insert_vmalloc_vmlist(struct vm_struct *vm)
1268{
1269 struct vm_struct *tmp, **p;
1267 1270
1271 vm->flags &= ~VM_UNLIST;
1268 write_lock(&vmlist_lock); 1272 write_lock(&vmlist_lock);
1269 for (p = &vmlist; (tmp = *p) != NULL; p = &tmp->next) { 1273 for (p = &vmlist; (tmp = *p) != NULL; p = &tmp->next) {
1270 if (tmp->addr >= vm->addr) 1274 if (tmp->addr >= vm->addr)
@@ -1275,6 +1279,13 @@ static void insert_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va,
1275 write_unlock(&vmlist_lock); 1279 write_unlock(&vmlist_lock);
1276} 1280}
1277 1281
1282static void insert_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va,
1283 unsigned long flags, void *caller)
1284{
1285 setup_vmalloc_vm(vm, va, flags, caller);
1286 insert_vmalloc_vmlist(vm);
1287}
1288
1278static struct vm_struct *__get_vm_area_node(unsigned long size, 1289static struct vm_struct *__get_vm_area_node(unsigned long size,
1279 unsigned long align, unsigned long flags, unsigned long start, 1290 unsigned long align, unsigned long flags, unsigned long start,
1280 unsigned long end, int node, gfp_t gfp_mask, void *caller) 1291 unsigned long end, int node, gfp_t gfp_mask, void *caller)
@@ -1313,7 +1324,18 @@ static struct vm_struct *__get_vm_area_node(unsigned long size,
1313 return NULL; 1324 return NULL;
1314 } 1325 }
1315 1326
1316 insert_vmalloc_vm(area, va, flags, caller); 1327 /*
1328 * When this function is called from __vmalloc_node_range,
1329 * we do not add vm_struct to vmlist here to avoid
1330 * accessing uninitialized members of vm_struct such as
1331 * pages and nr_pages fields. They will be set later.
1332 * To distinguish it from others, we use a VM_UNLIST flag.
1333 */
1334 if (flags & VM_UNLIST)
1335 setup_vmalloc_vm(area, va, flags, caller);
1336 else
1337 insert_vmalloc_vm(area, va, flags, caller);
1338
1317 return area; 1339 return area;
1318} 1340}
1319 1341
@@ -1381,17 +1403,20 @@ struct vm_struct *remove_vm_area(const void *addr)
1381 va = find_vmap_area((unsigned long)addr); 1403 va = find_vmap_area((unsigned long)addr);
1382 if (va && va->flags & VM_VM_AREA) { 1404 if (va && va->flags & VM_VM_AREA) {
1383 struct vm_struct *vm = va->private; 1405 struct vm_struct *vm = va->private;
1384 struct vm_struct *tmp, **p; 1406
1385 /* 1407 if (!(vm->flags & VM_UNLIST)) {
1386 * remove from list and disallow access to this vm_struct 1408 struct vm_struct *tmp, **p;
1387 * before unmap. (address range confliction is maintained by 1409 /*
1388 * vmap.) 1410 * remove from list and disallow access to
1389 */ 1411 * this vm_struct before unmap. (address range
1390 write_lock(&vmlist_lock); 1412 * confliction is maintained by vmap.)
1391 for (p = &vmlist; (tmp = *p) != vm; p = &tmp->next) 1413 */
1392 ; 1414 write_lock(&vmlist_lock);
1393 *p = tmp->next; 1415 for (p = &vmlist; (tmp = *p) != vm; p = &tmp->next)
1394 write_unlock(&vmlist_lock); 1416 ;
1417 *p = tmp->next;
1418 write_unlock(&vmlist_lock);
1419 }
1395 1420
1396 vmap_debug_free_range(va->va_start, va->va_end); 1421 vmap_debug_free_range(va->va_start, va->va_end);
1397 free_unmap_vmap_area(va); 1422 free_unmap_vmap_area(va);
@@ -1602,8 +1627,8 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
1602 if (!size || (size >> PAGE_SHIFT) > totalram_pages) 1627 if (!size || (size >> PAGE_SHIFT) > totalram_pages)
1603 return NULL; 1628 return NULL;
1604 1629
1605 area = __get_vm_area_node(size, align, VM_ALLOC, start, end, node, 1630 area = __get_vm_area_node(size, align, VM_ALLOC | VM_UNLIST,
1606 gfp_mask, caller); 1631 start, end, node, gfp_mask, caller);
1607 1632
1608 if (!area) 1633 if (!area)
1609 return NULL; 1634 return NULL;
@@ -1611,6 +1636,12 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
1611 addr = __vmalloc_area_node(area, gfp_mask, prot, node, caller); 1636 addr = __vmalloc_area_node(area, gfp_mask, prot, node, caller);
1612 1637
1613 /* 1638 /*
1639 * In this function, newly allocated vm_struct is not added
1640 * to vmlist at __get_vm_area_node(). so, it is added here.
1641 */
1642 insert_vmalloc_vmlist(area);
1643
1644 /*
1614 * A ref_count = 3 is needed because the vm_struct and vmap_area 1645 * A ref_count = 3 is needed because the vm_struct and vmap_area
1615 * structures allocated in the __get_vm_area_node() function contain 1646 * structures allocated in the __get_vm_area_node() function contain
1616 * references to the virtual address of the vmalloc'ed block. 1647 * references to the virtual address of the vmalloc'ed block.