Messages in this thread Patch in this message | | | From | Seth Jennings <> | Subject | [PATCH] staging: zcache: fix crash on cpu remove | Date | Thu, 6 Oct 2011 14:28:26 -0500 |
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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.
Based on v3.1-rc8
Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> --- drivers/staging/zcache/zcache-main.c | 10 ++++++++-- 1 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c index 462fbc2..41d1ba1 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; -- 1.7.4.1
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