{"id":"DEBIAN-CVE-2021-47394","details":"In the Linux kernel, the following vulnerability has been resolved:  netfilter: nf_tables: unlink table before deleting it  syzbot reports following UAF: BUG: KASAN: use-after-free in memcmp+0x18f/0x1c0 lib/string.c:955  nla_strcmp+0xf2/0x130 lib/nlattr.c:836  nft_table_lookup.part.0+0x1a2/0x460 net/netfilter/nf_tables_api.c:570  nft_table_lookup net/netfilter/nf_tables_api.c:4064 [inline]  nf_tables_getset+0x1b3/0x860 net/netfilter/nf_tables_api.c:4064  nfnetlink_rcv_msg+0x659/0x13f0 net/netfilter/nfnetlink.c:285  netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504  Problem is that all get operations are lockless, so the commit_mutex held by nft_rcv_nl_event() isn't enough to stop a parallel GET request from doing read-accesses to the table object even after synchronize_rcu().  To avoid this, unlink the table first and store the table objects in on-stack scratch space.","modified":"2026-09-01T20:04:37.596922046Z","published":"2024-05-21T15:15:24.710Z","upstream":["CVE-2021-47394"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2021-47394"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.14.12-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-47394.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.14.12-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-47394.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.14.12-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-47394.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}