From: Seth Jennings Date: Thu, 6 Oct 2011 19:28:26 +0000 (-0500) Subject: staging: zcache: fix crash on cpu remove X-Git-Tag: next-20111012~8^2~16 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=8550be08cbed164a8357491cc2c27cb99282b7ff;p=karo-tx-linux.git 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 Acked-by: Dave Hansen Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c index fbb400193e9e..dae2f4ee06a6 100644 --- a/drivers/staging/zcache/zcache-main.c +++ b/drivers/staging/zcache/zcache-main.c @@ -1357,8 +1357,14 @@ static int zcache_cpu_notifier(struct notifier_block *nb, kp->objnodes[kp->nr - 1] = NULL; kp->nr--; } - kmem_cache_free(zcache_obj_cache, kp->obj); - free_page((unsigned long)kp->page); + 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;