7.8

CVE-2021-47394

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.
Daten sind bereitgestellt durch National Vulnerability Database (NVD)
Linux ≫ Linux Kernel Version >= 5.12 < 5.14.10
Linux ≫ Linux Kernel Version5.15 Updaterc1
Linux ≫ Linux Kernel Version5.15 Updaterc2
Linux ≫ Linux Kernel Version5.15 Updaterc3
Zu dieser CVE wurde keine CISA KEV oder CERT.AT-Warnung gefunden.
EPSS Metriken
Typ Quelle Score Percentile
EPSS FIRST.org 0.02% 0.019
CVSS Metriken
Quelle Base Score Exploit Score Impact Score Vector String
nvd@nist.gov 7.8 1.8 5.9
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE-416 Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.