In the Linux kernel, the following vulnerability has been resolved:netfilter: nf_tables: reject QUEUE/DROP verdict parametersThis reverts commit e0abdadcc6e1.core.c:nf_hook_slow assumes that the upper 16 bits of NF_DROP
verdicts contain a valid errno, i.e. -EPERM, -EHOSTUNREACH or similar,
or 0.Due to the reverted commit, its possible to provide a positive
value, e.g. NF_ACCEPT (1), which results in use-after-free.Its not clear to me why this commit was made.NF_QUEUE is not used by nftables; "queue" rules in nftables
will result in use of "nft_queue" expression.If we later need to allow specifiying errno values from userspace
(do not know why), this has to call NF_DROP_GETERR and check that
"err <= 0" holds true.