The makefile in the Qualcomm components in Android before 2016-07-05 on Nexus 5 and 7 (2013) devices omits the -fno-strict-overflow option to gcc, which might allow attackers to gain privileges via a crafted application that leverages incorrect compiler optimization of an integer-overflow protection mechanism, aka Android internal bug 28821731 and Qualcomm internal bug CR691916.
https://source.codeaurora.org/quic/la/kernel/lk/commit/?id=c2119f1fba46f3b6e153aa018f15ee46fe6d5b76