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authorEric Blake <eblake@redhat.com>2020-03-20 10:05:07 -0500
committerMichael Roth <mdroth@linux.vnet.ibm.com>2020-03-24 11:32:19 -0500
commita23f38a72921fa915536a981a4f8a9134512f120 (patch)
treedcab1333de8db880f53282a2a089b731d485f202 /qga
parent807e2b6fce022707418bc8f61c069d91c613b3d2 (diff)
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qga: Fix undefined C behavior
The QAPI struct GuestFileWhence has a comment about how we are exploiting equivalent values between two different integer types shared in a union. But C says behavior is undefined on assignments to overlapping storage when the two types are not the same width, and indeed, 'int64_t value' and 'enum QGASeek name' are very likely to be different in width. Utilize a temporary variable to fix things. Reported-by: Peter Maydell <peter.maydell@linaro.org> Fixes: 0b4b49387 Fixes: Coverity CID 1421990 Signed-off-by: Eric Blake <eblake@redhat.com> Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Diffstat (limited to 'qga')
-rw-r--r--qga/commands.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/qga/commands.c b/qga/commands.c
index f8852be..4471a9f 100644
--- a/qga/commands.c
+++ b/qga/commands.c
@@ -482,10 +482,15 @@ done:
* the guest's SEEK_ constants. */
int ga_parse_whence(GuestFileWhence *whence, Error **errp)
{
- /* Exploit the fact that we picked values to match QGA_SEEK_*. */
+ /*
+ * Exploit the fact that we picked values to match QGA_SEEK_*;
+ * however, we have to use a temporary variable since the union
+ * members may have different size.
+ */
if (whence->type == QTYPE_QSTRING) {
+ int value = whence->u.name;
whence->type = QTYPE_QNUM;
- whence->u.value = whence->u.name;
+ whence->u.value = value;
}
switch (whence->u.value) {
case QGA_SEEK_SET: