aspeed: check for negative values returned by blk_getlength()

write_boot_rom() does not check for negative values. This is more a
problem for coverity than the actual code as the size of the flash
device is checked when the m25p80 object is created. If there is
anything wrong with the backing file, we should not even reach that
path.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-id: 1486648058-520-2-git-send-email-clg@kaod.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 12 insertions, 2 deletions

diff --git a/hw/arm/aspeed.c b/hw/arm/aspeed.c
index a92c2f1c36..ac9cbd66b7 100644
--- a/hw/arm/aspeed.c
+++ b/hw/arm/aspeed.c
@@ -113,9 +113,19 @@ static void write_boot_rom(DriveInfo *dinfo, hwaddr addr, size_t rom_size,
 {
     BlockBackend *blk = blk_by_legacy_dinfo(dinfo);
     uint8_t *storage;
+    int64_t size;
 
-    if (rom_size > blk_getlength(blk)) {
-        rom_size = blk_getlength(blk);
+    /* The block backend size should have already been 'validated' by
+     * the creation of the m25p80 object.
+     */
+    size = blk_getlength(blk);
+    if (size <= 0) {
+        error_setg(errp, "failed to get flash size");
+        return;
+    }
+
+    if (rom_size > size) {
+        rom_size = size;
     }
 
     storage = g_new0(uint8_t, rom_size);