File 0150-qcow2-Fix-Coverity-warning-when-cal.patch of Package qemu.18973

Overview Repositories Revisions Requests Users Attributes Meta

File 0150-qcow2-Fix-Coverity-warning-when-cal.patch of Package qemu.18973

From: Alberto Garcia <berto@igalia.com>
Date: Mon, 28 May 2018 17:01:28 +0200
Subject: qcow2: Fix Coverity warning when calculating the refcount cache size

Include-If: %if 0%{?suse_version} == 1315

MIN_REFCOUNT_CACHE_SIZE is 4 and the cluster size is guaranteed to be
at most 2MB, so the minimum refcount cache size (in bytes) is always
going to fit in a 32-bit integer.

Coverity doesn't know that, and since we're storing the result in a
uint64_t (*refcount_cache_size) it thinks that we need the 64 bits and
that we probably want to do a 64-bit multiplication to prevent the
result from being truncated.

This is a false positive in this case, but it's a fair warning.
We could do a 64-bit multiplication to get rid of it, but since we
know that a 32-bit variable is enough to store this value let's simply
reuse min_refcount_cache, make it a normal int and stop doing casts.

Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 7af5eea9b34ffb7a9a9fc25ba71998a02b76e159)
[LM: BSC#1139926]
Signed-off-by: Lin Ma <lma@suse.com>
---
 block/qcow2.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/block/qcow2.c b/block/qcow2.c
index bb70f164ce91870676d222d9a8d9..5bbde3d22f04c96cdcc3f0c4e3ee 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -742,6 +742,7 @@ static void read_cache_sizes(BlockDriverState *bs, QemuOpts *opts,
     BDRVQcow2State *s = bs->opaque;
     uint64_t combined_cache_size;
     bool l2_cache_size_set, refcount_cache_size_set, combined_cache_size_set;
+    int min_refcount_cache = MIN_REFCOUNT_CACHE_SIZE * s->cluster_size;
 
     combined_cache_size_set = qemu_opt_get(opts, QCOW2_OPT_CACHE_SIZE);
     l2_cache_size_set = qemu_opt_get(opts, QCOW2_OPT_L2_CACHE_SIZE);
@@ -775,8 +776,6 @@ static void read_cache_sizes(BlockDriverState *bs, QemuOpts *opts,
         } else {
             uint64_t virtual_disk_size = bs->total_sectors * BDRV_SECTOR_SIZE;
             uint64_t max_l2_cache = virtual_disk_size / (s->cluster_size / 8);
-            uint64_t min_refcount_cache =
-                (uint64_t) MIN_REFCOUNT_CACHE_SIZE * s->cluster_size;
 
             /* Assign as much memory as possible to the L2 cache, and
              * use the remainder for the refcount cache */
@@ -796,7 +795,7 @@ static void read_cache_sizes(BlockDriverState *bs, QemuOpts *opts,
                                  * s->cluster_size);
         }
         if (!refcount_cache_size_set) {
-            *refcount_cache_size = MIN_REFCOUNT_CACHE_SIZE * s->cluster_size;
+            *refcount_cache_size = min_refcount_cache;
         }
     }
 }

Places

File 0150-qcow2-Fix-Coverity-warning-when-cal.patch of Package qemu.18973

Places