Commit 8550be08 authored Oct 06, 2011 by Seth Jennings Committed by Greg Kroah-Hartman Oct 11, 2011

staging: zcache: fix crash on cpu remove



In the case that a cpu is taken offline before zcache_do_preload() is
ever called on the cpu, the per-cpu zcache_preloads structure will
be uninitialized.  In the CPU_DEAD case for zcache_cpu_notifier(),
kp->obj is not checked before calling kmem_cache_free() on it.
If it is NULL, a crash results.

This patch ensures that both kp->obj and kp->page are not NULL before
calling the respective free functions. In practice, just checking
one or the other should be sufficient since they are assigned together
in zcache_do_preload(), but I check both for safety.

Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Acked-by: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

parent 5ba321cf

drivers/staging/zcache/zcache-main.c

+8 −2

Original line number	Diff line number	Diff line
		@@ -1357,8 +1357,14 @@ static int zcache_cpu_notifier(struct notifier_block *nb,
		kp->objnodes[kp->nr - 1] = NULL;
		kp->nr--;
		}
		if (kp->obj) {
		kmem_cache_free(zcache_obj_cache, kp->obj);
		kp->obj = NULL;
		}
		if (kp->page) {
		free_page((unsigned long)kp->page);
		kp->page = NULL;
		}
		break;
		default:
		break;