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>

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index bc2f700..0279eb1 100644 (file)
--- 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;
 }