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Subject[PATCH 2/2] staging: zcache: fix memory corruption bug
Date
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>
---
drivers/staging/zcache/zcache-main.c | 6 ++----
1 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c
index 46c7c04..7073465 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;
--
1.7.5.4


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