Description: DoS via infinite loop with a zero-length biovec request issued by the block subsystem
References:
 https://www.openwall.com/lists/oss-security/2020/09/30/1
Notes:
 carnil> The commit mentions that this was broken in 1bdc76aea115
 carnil> "iov_iter: use bvec iterator to implement iterate_bvec()" in
 carnil> 4.8-rc1, the fixing commit was backported to various stable
 carnil> versions 4.9.236, v4.14.197, 4.19.144, 5.4.64, and 5.8.8.
Bugs:
upstream: released (5.9-rc4) [7e24969022cbd61ddc586f14824fc205661bb124]
4.19-upstream-stable: released (4.19.144) [b48bcb664b657ae94b19c0728978c88e012f7a37]
4.9-upstream-stable: released (4.9.236) [0c7cee63ec92b316f8b891b667177a080b670566]
sid: released (5.8.10-1)
4.19-buster-security: released (4.19.146-1)
4.9-stretch-security: released (4.9.240-1)