Use After Free Affecting kernel package, versions *
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Test your applications- Snyk ID SNYK-RHEL7-KERNEL-7003219
- published 22 May 2024
- disclosed 21 May 2024
Introduced: 21 May 2024
CVE-2021-47394 Open this link in a new tabHow to fix?
There is no fixed version for RHEL:7 kernel.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel package and not the kernel package as distributed by RHEL.
See How to fix? for RHEL:7 relevant fixed versions and status.
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.