Description: net/x25: prevent a couple of overflows
References:
 https://www.openwall.com/lists/oss-security/2020/11/15/2
 https://www.openwall.com/lists/oss-security/2021/03/17/17
 https://bugzilla.redhat.com/show_bug.cgi?id=1908251
Notes:
Bugs:
upstream: released (5.10-rc7) [6ee50c8e262a0f0693dad264c3c99e30e6442a56]
5.10-upstream-stable: N/A "Fixed before branching point"
4.19-upstream-stable: released (4.19.162) [304c080fc33258e3b177b6f0736b97d54e6fea3b]
4.9-upstream-stable: released (4.9.248) [4596762761d5e0f843fc920babb4506e2d3c6c90]
sid: released (5.9.15-1)
4.19-buster-security: released (4.19.171-1)
4.9-stretch-security: released (4.9.258-1)