[PULL,11/15] block: Fix integer promotion error in bdrv_getlength()

Commit Message

Max Reitz Nov. 9, 2020, 5:38 p.m. UTC

From: Eric Blake <[e-mail]>

Back in 2015, we attempted to fix error reporting for images that
claimed to have more than INT64_MAX/512 sectors, but due to the type
promotions caused by BDRV_SECTOR_SIZE being unsigned, this
inadvertently forces all negative ret values to be slammed into -EFBIG
rather than the original error.  While we're at it, we can avoid the
confusing ?: by spelling the logic more directly.

Fixes: 4a9c9ea0d3
Reported-by: Guoyi Tu <[e-mail]>
Signed-off-by: Eric Blake <[e-mail]>
Message-Id: <[e-mail]>
Reviewed-by: Alberto Garcia <[e-mail]>
Signed-off-by: Max Reitz <[e-mail]>
---
 block.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

Patch

diff --git a/block.c b/block.c
index 56bacc9e9f..2fd932154e 100644
--- a/block.c
+++ b/block.c
@@ -5091,8 +5091,13 @@  int64_t bdrv_getlength(BlockDriverState *bs)
 {
     int64_t ret = bdrv_nb_sectors(bs);
 
-    ret = ret > INT64_MAX / BDRV_SECTOR_SIZE ? -EFBIG : ret;
-    return ret < 0 ? ret : ret * BDRV_SECTOR_SIZE;
+    if (ret < 0) {
+        return ret;
+    }
+    if (ret > INT64_MAX / BDRV_SECTOR_SIZE) {
+        return -EFBIG;
+    }
+    return ret * BDRV_SECTOR_SIZE;
 }
 
 /* return 0 as number of sectors if no device present or error */