parisc: Fix sglist access in ccio-dma.c

stable inclusion
from stable-v5.10.102
commit 7756716872990ef8173e226f689c5cf17528ebdb
bugzilla: https://gitee.com/openeuler/kernel/issues/I567K6

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7756716872990ef8173e226f689c5cf17528ebdb

--------------------------------

commit d7da660c upstream.

This patch implements the same bug fix to ccio-dma.c as to sba_iommu.c.
It ensures that only the allocated entries of the sglist are accessed.
Signed-off-by: NJohn David Anglin <dave.anglin@bell.net>
Cc: stable@vger.kernel.org
Signed-off-by: NHelge Deller <deller@gmx.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYu Liao <liaoyu15@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/parisc/ccio-dma.c

@@ -1003,7 +1003,7 @@ ccio_unmap_sg(struct device *dev, struct scatterlist *sglist, int nents,
 	ioc->usg_calls++;
 #endif
 
-	while(sg_dma_len(sglist) && nents--) {
+	while (nents && sg_dma_len(sglist)) {
 
 #ifdef CCIO_COLLECT_STATS
 		ioc->usg_pages += sg_dma_len(sglist) >> PAGE_SHIFT;
@@ -1011,6 +1011,7 @@ ccio_unmap_sg(struct device *dev, struct scatterlist *sglist, int nents,
 		ccio_unmap_page(dev, sg_dma_address(sglist),
 				  sg_dma_len(sglist), direction, 0);
 		++sglist;
+		nents--;
 	}
 
 	DBG_RUN_SG("%s() DONE (nents %d)\n", __func__, nents);