I began noticing a race when reserving VNC ports as described here
https://www.redhat.com/archives/libvir-list/2010-November/msg00379.html
Turns out that we were not initializing the size field of bitmap
struct when allocating the bitmap. This subsequently caused
virBitmapSetBit() to fail since bitmap->size is 0, hence we never
actually reserved the port.
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.
Signed-off-by: Cole Robinson <crobinso@redhat.com>
V2:
- Move bitmap impl to src/util/bitmap.[ch]
- Use CHAR_BIT instead of explicit '8'
- Use size_t instead of unsigned int
- Fix calculation of bitmap size in virBitmapAlloc
- Ensure bit is within range of map in the set, clear, and get
operations
- Use bool in virBitmapGetBit
- Add virBitmapFree to free-like funcs in cfg.mk
V3:
- Check for overflow in virBitmapAlloc
- Fix copy and paste bug in virBitmapAlloc
- Use size_t in prototypes
- Add ATTRIBUTE_NONNULL in prototypes where appropriate
and remove NULL check from impl
V4:
- Add ATTRIBUTE_RETURN_CHECK in prototypes where appropriate.
