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[PULL,v2,for-2.1,07/22] block: Make qiov match the request size until EOF

Message ID 1405338192-18850-8-git-send-email-kwolf@redhat.com
State New
Headers show

Commit Message

Kevin Wolf July 14, 2014, 11:42 a.m. UTC 
If a read request goes across EOF, the block driver sees a shortened
request that stops at EOF (the rest is memsetted in block.c), however
the original qiov was used for this request.

This patch makes the qiov size match the request size, avoiding a
potential buffer overflow in raw-posix.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
---
 block.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)
diff mbox

Patch

diff --git a/block.c b/block.c
index 510430d..0143268 100644
--- a/block.c
+++ b/block.c
@@ -3054,8 +3054,20 @@  static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs,
         max_nb_sectors = ROUND_UP(MAX(0, total_sectors - sector_num),
                                   align >> BDRV_SECTOR_BITS);
         if (max_nb_sectors > 0) {
-            ret = drv->bdrv_co_readv(bs, sector_num,
-                                     MIN(nb_sectors, max_nb_sectors), qiov);
+            QEMUIOVector local_qiov;
+            size_t local_sectors;
+
+            max_nb_sectors = MIN(max_nb_sectors, SIZE_MAX / BDRV_SECTOR_BITS);
+            local_sectors = MIN(max_nb_sectors, nb_sectors);
+
+            qemu_iovec_init(&local_qiov, qiov->niov);
+            qemu_iovec_concat(&local_qiov, qiov, 0,
+                              local_sectors * BDRV_SECTOR_SIZE);
+
+            ret = drv->bdrv_co_readv(bs, sector_num, local_sectors,
+                                     &local_qiov);
+
+            qemu_iovec_destroy(&local_qiov);
         } else {
             ret = 0;
         }