From: Seth Jennings <sjenning@linux.vnet.ibm.com>
Date: Tue, 28 Feb 2012 22:02:23 +0000 (-0600)
Subject: staging: zcache: fix memory corruption bug
X-Git-Tag: MMI-PSA29.97-13-9~17268^2~100^2
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=041aba19b916ddfd5254c80ef413ef8a7e76c8ad;p=GitHub%2FMotorolaMobilityLLC%2Fkernel-slsi.git

staging: zcache: fix memory corruption bug

This patch fixes a bug where the zv code writes before the allocated
buffer, resulting in system memory corruption. This was introduced
during the switch from xvmalloc to zsmalloc.

Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c
index 46c7c04c2451..70734652f724 100644
--- a/drivers/staging/zcache/zcache-main.c
+++ b/drivers/staging/zcache/zcache-main.c
@@ -701,7 +701,6 @@ static struct zv_hdr *zv_create(struct zs_pool *pool, uint32_t pool_id,
 	u32 size = clen + sizeof(struct zv_hdr);
 	int chunks = (size + (CHUNK_SIZE - 1)) >> CHUNK_SHIFT;
 	void *handle = NULL;
-	char *buf;
 
 	BUG_ON(!irqs_disabled());
 	BUG_ON(chunks >= NCHUNKS);
@@ -710,14 +709,13 @@ static struct zv_hdr *zv_create(struct zs_pool *pool, uint32_t pool_id,
 		goto out;
 	atomic_inc(&zv_curr_dist_counts[chunks]);
 	atomic_inc(&zv_cumul_dist_counts[chunks]);
-	zv = (struct zv_hdr *)((char *)cdata - sizeof(*zv));
+	zv = zs_map_object(pool, handle);
 	zv->index = index;
 	zv->oid = *oid;
 	zv->pool_id = pool_id;
 	zv->size = clen;
 	SET_SENTINEL(zv, ZVH);
-	buf = zs_map_object(pool, handle);
-	memcpy(buf, zv, clen + sizeof(*zv));
+	memcpy((char *)zv + sizeof(struct zv_hdr), cdata, clen);
 	zs_unmap_object(pool, handle);
 out:
 	return handle;