Description: Double-free in ion_system_heap.c
References:
 https://bugzilla.redhat.com/show_bug.cgi?id=1661435
 https://www.codeaurora.org/security-bulletin/2018/12/03/december-2018-code-aurora-security-bulletin#_CVE-2018-11987
 https://source.codeaurora.org/quic/la/kernel/msm-4.9/commit/?id=5e9ffcfa152ecb2832990c42fcd8a0f2e63c2c04
Notes:
 carnil> Affects potentially upstream as well in
 carnil> drivers/staging/android/ion/ion_system_heap.c . For Debian the
 carnil> code is not build so would be unimportant.
 carnil> Possibly introduced in e7f63771b60e7802c5a9b437c5ab1a8e33a0bb35 (4.9-rc1)?
 bwh> There doesn't seem to be any path to double-free in any upstream version.
Bugs:
upstream: N/A "Vulnerable code path not present"
4.19-upstream-stable: N/A "Vulnerable code path not present"
4.9-upstream-stable: N/A "Vulnerable code path not present"
3.16-upstream-stable: N/A "Vulnerable code path not present"
sid: N/A "Vulnerable code path not present"
4.9-stretch-security: N/A "Vulnerable code path not present"
3.16-jessie-security: N/A "Vulnerable code path not present"