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[v2,4/4] block/vdi.c: Make SECTOR_SIZE constant 64-bits

Message ID 20241008164708.2966400-5-peter.maydell@linaro.org
State New
Headers show
Series block: Miscellaneous minor Coverity fixes | expand

Commit Message

Peter Maydell Oct. 8, 2024, 4:47 p.m. UTC 
Make the VDI SECTOR_SIZE define be a 64-bit constant; this matches
how we define BDRV_SECTOR_SIZE.  The benefit is that it means that we
don't need to carefully cast to 64-bits when doing operations like
"n_sectors * SECTOR_SIZE" to avoid doing a 32x32->32 multiply, which
might overflow, and which Coverity and other static analysers tend to
warn about.

The specific potential overflow Coverity is highlighting is the one
at the end of vdi_co_pwritev() where we write out n_sectors sectors
to the block map.  This is very unlikely to actually overflow, since
the block map has 4 bytes per block and the maximum number of blocks
in the image must fit into a 32-bit integer.  So this commit is not
fixing a real-world bug.

An inspection of all the places currently using SECTOR_SIZE in the
file shows none which care about the change in its type, except for
one call to error_setg() which needs the format string adjusting.

Resolves: Coverity CID 1508076
Suggested-by: Kevin Wolf <kwolf@redhat.com>
---
v1->v2: v1 just added the (uint64_t) cast for the specific
issue that Coverity was warning about; v2 is entirely different
and takes the approach Kevin suggested in review on v1.
---
 block/vdi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
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Patch

diff --git a/block/vdi.c b/block/vdi.c
index 149e15c8314..26f7638f1fc 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -87,7 +87,7 @@ 
 /* Command line option for static images. */
 #define BLOCK_OPT_STATIC "static"
 
-#define SECTOR_SIZE 512
+#define SECTOR_SIZE 512ULL
 #define DEFAULT_CLUSTER_SIZE 1048576
 /* Note: can't use 1 * MiB, because it's passed to stringify() */
 
@@ -442,7 +442,7 @@  static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
         goto fail;
     } else if (header.sector_size != SECTOR_SIZE) {
         error_setg(errp, "unsupported VDI image (sector size %" PRIu32
-                   " is not %u)", header.sector_size, SECTOR_SIZE);
+                   " is not %llu)", header.sector_size, SECTOR_SIZE);
         ret = -ENOTSUP;
         goto fail;
     } else if (header.block_size != DEFAULT_CLUSTER_SIZE) {