[Qemu-devel] [PATCH v11 4/5] qemu-iotests: s390x: fix test 049, reject negative sizes in QemuOpts

[Bo Tu <tubo@linux.vnet.ibm.com>]

when creating an image qemu-img enable us specifying the size of the
image using -o size=xx options. But when we specify an invalid size
such as a negtive size then different platform gives different result.

parse_option_size() function in util/qemu-option.c will be called to
parse the size, a cast was called in the function to cast the input
(saved as a double in the function) size to an unsigned int64 value,
when the input is a negtive value or exceeds the maximum of uint64, then
the result is undefined.

According to C99 6.3.1.4, the result of converting a floating point
number to an integer that cannot represent the (integer part of) number
is undefined.  And sure enough the results are different on x86 and
s390.

C99 Language spec 6.3.1.4 Real floating and integers:
the result of this assignment/cast is undefined if the float is not
in the open interval (-1, U<type>_MAX+1).

Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Sascha Silbe <silbe@linux.vnet.ibm.com>
Signed-off-by: Bo Tu <tubo@linux.vnet.ibm.com>
---
 tests/qemu-iotests/049.out | 10 ++++------
 util/qemu-option.c         |  5 +++++
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/tests/qemu-iotests/049.out b/tests/qemu-iotests/049.out
index 9f93666..8884543 100644
--- a/tests/qemu-iotests/049.out
+++ b/tests/qemu-iotests/049.out
@@ -95,17 +95,15 @@ qemu-img create -f qcow2 TEST_DIR/t.qcow2 -- -1024
 qemu-img: Image size must be less than 8 EiB!
 
 qemu-img create -f qcow2 -o size=-1024 TEST_DIR/t.qcow2
-qemu-img: qcow2 doesn't support shrinking images yet
-qemu-img: TEST_DIR/t.qcow2: Could not resize image: Operation not supported
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 size=-1024 encryption=off cluster_size=65536 lazy_refcounts=off refcount_bits=16
+qemu-img: Parameter 'size' expects a non-negative number below 2^64
+qemu-img: TEST_DIR/t.qcow2: Invalid options for file format 'qcow2'
 
 qemu-img create -f qcow2 TEST_DIR/t.qcow2 -- -1k
 qemu-img: Image size must be less than 8 EiB!
 
 qemu-img create -f qcow2 -o size=-1k TEST_DIR/t.qcow2
-qemu-img: qcow2 doesn't support shrinking images yet
-qemu-img: TEST_DIR/t.qcow2: Could not resize image: Operation not supported
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 size=-1024 encryption=off cluster_size=65536 lazy_refcounts=off refcount_bits=16
+qemu-img: Parameter 'size' expects a non-negative number below 2^64
+qemu-img: TEST_DIR/t.qcow2: Invalid options for file format 'qcow2'
 
 qemu-img create -f qcow2 TEST_DIR/t.qcow2 -- 1kilobyte
 qemu-img: Invalid image size specified! You may use k, M, G, T, P or E suffixes for
diff --git a/util/qemu-option.c b/util/qemu-option.c
index efe9d27..efd6f02 100644
--- a/util/qemu-option.c
+++ b/util/qemu-option.c
@@ -180,6 +180,11 @@ void parse_option_size(const char *name, const char *value,
 
     if (value != NULL) {
         sizef = strtod(value, &postfix);
+        if (sizef < 0 || sizef > UINT64_MAX) {
+            error_setg(errp, QERR_INVALID_PARAMETER_VALUE, name,
+                             "a non-negative number below 2^64");
+            return;
+        }
         switch (*postfix) {
         case 'T':
             sizef *= 1024;
-- 
2.3.0