Description: seq_buf: Fix overflow in seq_buf_putmem_hex()
References:
 https://lore.kernel.org/all/20210626032156.47889-1-yun.zhou@windriver.com/T/#u
 https://lore.kernel.org/lkml/20210625122453.5e2fe304@oasis.local.home/
Notes:
Bugs:
upstream: released (5.14-rc1) [d3b16034a24a112bb83aeb669ac5b9b01f744bb7]
6.1-upstream-stable: N/A "Fixed before branching point"
5.10-upstream-stable: released (5.10.51) [f9fb4986f4d81182f938d16beb4f983fe71212aa]
4.19-upstream-stable: released (4.19.198) [1f4c6061fccee64b2072b28dfa3e93cf859c4c0a]
sid: released (5.14.6-1)
5.10-bullseye-security: released (5.10.70-1)
4.19-buster-security: released (4.19.208-1)