commit f1151c3ef7542a4df602338e13305d7bbb24e6d6
author Ivan Lozano <ivanlozano@google.com> Thu Dec 07 13:08:52 2017 -0800
committer Ivan Lozano <ivanlozano@google.com> Tue Dec 19 15:30:05 2017 -0800
tree 54fcd07c2f5d825f5e4623166c5c090909834c64
parent 240201e27b1722009907a31983825668f2416ec2

Fix integer sanitizer in clearkey.

Calculating index sometimes causes an unsigned integer overflow. This
throws a runtime error on integer sanitized builds.

 runtime error: unsigned integer overflow: 0 - 1 cannot be represented
 in type 'unsigned int'

Since this gets implicitly converted to ssize_t anyhow, make the
conversion explicit before decrementing to avoid the overflow.

Bug: 30969751
Test: Compiles.
Change-Id: Ibd39c1ba0dc64673743672ffc70c22c09f8e828a
Merged-In: Ibd39c1ba0dc64673743672ffc70c22c09f8e828a