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e33e7139f0
Before the variable 'bits' was initialized with 0 (commit 3470cd860d517760b13e26d97b6a842ff72687a1), the following bug was possible. A function call with an empty bitmap leads to undefined behavior. Because if 'bitmap->map_len == 0' 'unusedBits' will be <= 0 and 'sz == 1'. So the non global and non static variable 'bits' would have never been set. Consequently the check 'bits == 0' results in undefined behavior. This patch clarifies the current version of the function by handling the empty bitmap explicitly. Also, for an empty bitmap there is obviously no bit set so we can just return -1 (indicating no bit set) right away. The explicit check for 'bits == 0' after the loop is unnecessary because we only get to this point if no set bit was found. Reviewed-by: Boris Fiuczynski <fiuczy@linux.vnet.ibm.com> Reviewed-by: Sascha Silbe <silbe@linux.vnet.ibm.com> Reviewed-by: Bjoern Walk <bwalk@linux.vnet.ibm.com> Signed-off-by: Marc Hartmayer <mhartmay@linux.vnet.ibm.com> (cherry picked from commit 7cd01a248b3995909adad29a6edbe76d3d16510f)
LibVirt : simple API for virtualization
Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.
Daniel Veillard <veillard@redhat.com>