Eric Blake wrote:
On 06/01/2010 01:10 PM, Cole Robinson wrote:
If VM startup fails early enough (can't find a referenced USB device), libvirtd will crash trying to clear the VNC port bit, since port = 0, which overflows us out of the bitmap bounds.
Fix this by being more defensive in the bitmap operations, and only clearing a previously set VNC port.
+++ b/src/util/bitmap.c @@ -118,7 +118,7 @@ int virBitmapSetBit(virBitmapPtr bitmap, size_t b) */ int virBitmapClearBit(virBitmapPtr bitmap, size_t b) { - if (b > bitmap->size - 1) + if (bitmap->size != 0 && b > bitmap->size - 1)
I think this could use a v2: virBitmapSetBit and virBitmapGetBit should get the same treatment for bounds checking.
Meanwhile, we already reject attempts to create a bitmap with SIZE_MAX bits. Therefore, since b is unsigned, we can safely avoid the && and instead do the computation via a single comparison:
if (bitmap->size <= b) return -1;
For that matter, should virBitmapAlloc(0) return NULL, instead of it's current behavior of allocating an (empty) bitmap?
Yes, you are right - especially since there is no grow operation :-). I should have returned NULL for size 0 request in the original version. Regards, Jim