Description: error handling issues in blkback's grant mapping
References:
 https://xenbits.xen.org/xsa/advisory-365.html
 https://lore.kernel.org/lkml/20210216124015.28923-1-jgross@suse.com/
Notes:
Bugs:
upstream: released (5.12-rc1) [871997bc9e423f05c7da7c9178e62dde5df2a7f8]
5.10-upstream-stable: released (5.10.18) [00805af45a21729e2901a37914992786a0d32c46]
4.19-upstream-stable: released (4.19.177) [98f16e171e2849dba76e2e0346e914452c030dc5]
4.9-upstream-stable: released (4.9.258) [4cec38115dfd5d5c123ece4f4a55165a5a2e8cc0]
sid: released (5.10.19-1)
4.19-buster-security: released (4.19.177-1)
4.9-stretch-security: released (4.9.258-1)