libnvdimm/pmem: fix a possible OOB access when read and write pmem

If offset is not zero and length is bigger than PAGE_SIZE,
this will cause to out of boundary access to a page memory

Fixes: 98cc093cba1e ("block, THP: make block_device_operations.rw_page support THP")
Co-developed-by: Liang ZhiCheng <liangzhicheng@baidu.com>
Signed-off-by: Liang ZhiCheng <liangzhicheng@baidu.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index bc2f700feef8..0279eb1da3ef 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -113,13 +113,13 @@ static void write_pmem(void *pmem_addr, struct page *page,
 
         while (len) {
                 mem = kmap_atomic(page);
-                chunk = min_t(unsigned int, len, PAGE_SIZE);
+                chunk = min_t(unsigned int, len, PAGE_SIZE - off);
                 memcpy_flushcache(pmem_addr, mem + off, chunk);
                 kunmap_atomic(mem);
                 len -= chunk;
                 off = 0;
                 page++;
-                pmem_addr += PAGE_SIZE;
+                pmem_addr += chunk;
         }
 }
 
@@ -132,7 +132,7 @@ static blk_status_t read_pmem(struct page *page, unsigned int off,
 
         while (len) {
                 mem = kmap_atomic(page);
-                chunk = min_t(unsigned int, len, PAGE_SIZE);
+                chunk = min_t(unsigned int, len, PAGE_SIZE - off);
                 rem = memcpy_mcsafe(mem + off, pmem_addr, chunk);
                 kunmap_atomic(mem);
                 if (rem)
@@ -140,7 +140,7 @@ static blk_status_t read_pmem(struct page *page, unsigned int off,
                 len -= chunk;
                 off = 0;
                 page++;
-                pmem_addr += PAGE_SIZE;
+                pmem_addr += chunk;
         }
         return BLK_STS_OK;
 }