Re: FIX [1/2] slub: Do not dereference NULL pointer in node_match
From: Christoph Lameter <hidden>
Date: 2013-01-24 15:14:44
Also in:
linux-mm
On Wed, 23 Jan 2013, Simon Jeons wrote:
On Wed, 2013-01-23 at 21:45 +0000, Christoph Lameter wrote:quoted
The variables accessed in slab_alloc are volatile and therefore the page pointer passed to node_match can be NULL. The processing of data in slab_alloc is tentative until either the cmpxhchg succeeds or the __slab_alloc slowpath is invoked. Both are able to perform the same allocation from the freelist. Check for the NULL pointer in node_match. A false positive will lead to a retry of the loop in __slab_alloc.Hi Christoph, Since page_to_nid(NULL) will trigger bug, then how can run into __slab_alloc?
page = NULL -> node_match(NULL, xx) = 0 -> call into __slab_alloc. __slab_alloc() will check for !c->page which requires the assignment of a new per cpu slab page. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>