Description: ip: frags: fix crash in ip_do_fragment()
References:
 https://www.openwall.com/lists/oss-security/2018/09/18/1
 https://bugzilla.redhat.com/show_bug.cgi?id=1629636
Notes:
 carnil> fa0f527358bd (4.19-rc1) is the introducing commit
 carnil> beeing part of the (upstream) fixes for CVE-2018-5391.
 carnil> There is no stable release which backported this
 carnil> (without) 5d407b071dc3. In fact not yet either in
 carnil> a 4.18.x or 4.9.x.
 carnil> When upstream fixes for CVE-2018-5391 land in Debian
 carnil> branch or are in a stable version, then 5d407b071dc3
 carnil> needs to be added to not make the CVE-2018-14641
 carnil> open.
 carnil> For experimental suite technically it was affected
 carnil> and fixed though with 4.19~rc4-1~exp1 upload.
Bugs:
upstream: released (4.19-rc4) [5d407b071dc369c26a38398326ee2be53651cfe4]
4.9-upstream-stable: N/A "fa0f527358bd not backported"
3.16-upstream-stable: N/A "fa0f527358bd not backported"
sid: N/A "Vulnerable code not present"
4.9-stretch-security: N/A "Vulnerable code not present"
3.16-jessie-security: N/A "Vulnerable code not present"