If data[0] were > 128 (that is, if the full size, encoded in big endian
were > 2 GB), the result of the OR chain would be a negative int (due to
C integer promotion rules). We're shifting into the sign bit, which is
either implementation-defined behavior or, worse, undefined behavior.
This negative number is then sign-extended to ulong (64-bit on 64-bit
platforms), which then becomes a big number. This code was probably
written with only 32-bit in mind, where there would be no size extension
(sign or otherwise).
This isn't too bad because there's a size check for the max size of
QByteArray a few lines below, but we can fix it, so let's do it.
Found by Coverity, CID 22530.
Change-Id: I42e7ef1a481840699a8dffff1407ea6c22e1a0ec
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
84a806589f