CVE-2024-35900: netfilter: nf_tables: reject new basechain after table flag update

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nftables: reject new basechain after table flag update

When dormant flag is toggled, hooks are disabled in the commit phase by iterating over current chains in table (existing and new).

The following configuration allows for an inconsistent state:

add table x add chain x y { type filter hook input priority 0; } add table x { flags dormant; } add chain x w { type filter hook input priority 1; }

which triggers the following warning when trying to unregister chain w which is already unregistered.

[ 127.322252] WARNING: CPU: 7 PID: 1211 at net/netfilter/core.c:50 1 nfunregisternethook+0x21a/0x260 [...] [ 127.322519] Call Trace: [ 127.322521] <TASK> [ 127.322524] ? warn+0x9f/0x1a0 [ 127.322531] ? nfunregisternethook+0x21a/0x260 [ 127.322537] ? reportbug+0x1b1/0x1e0 [ 127.322545] ? handlebug+0x3c/0x70 [ 127.322552] ? excinvalidop+0x17/0x40 [ 127.322556] ? asmexcinvalidop+0x1a/0x20 [ 127.322563] ? kasansavefreeinfo+0x3b/0x60 [ 127.322570] ? nfunregisternethook+0x6a/0x260 [ 127.322577] ? nfunregisternethook+0x21a/0x260 [ 127.322583] ? nfunregisternethook+0x6a/0x260 [ 127.322590] ? nftablesunregisterhook+0x8a/0xe0 [nftables] [ 127.322655] nfttabledisable+0x75/0xf0 [nftables] [ 127.322717] nftablescommit+0x2571/0x2620 [nftables]

— NVD

Linux Kernel is vulnerable to a denial of service, caused by a flaw when trying to unregister and already unregistered chain. By sending a specially crafted request, a local authenticated attacker could exploit this vulnerability to cause a denial of service condition.

— IBM