CVE-2024-27012: netfilter: nf_tables: restore set elements when delete set fails
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nftables: restore set elements when delete set fails
From abort path, nftmapelemactivate() needs to restore refcounters to the original state. Currently, it uses the set->ops->walk() to iterate over these set elements. The existing set iterator skips inactive elements in the next generation, this does not work from the abort path to restore the original state since it has to skip active elements instead (not inactive ones).
This patch moves the check for inactive elements to the set iterator callback, then it reverses the logic for the .activate case which needs to skip active elements.
Toggle next generation bit for elements when delete set command is invoked and call nftclear() from .activate (abort) path to restore the next generation bit.
The splat below shows an object in mappings memleak:
[43929.457523] ------------[ cut here ]------------ [43929.457532] WARNING: CPU: 0 PID: 1139 at include/net/netfilter/nftables.h:1237 nftsetelemdatadeactivate+0xe4/0xf0 [nftables] [...] [43929.458014] RIP: 0010:nftsetelemdatadeactivate+0xe4/0xf0 [nftables] [43929.458076] Code: 83 f8 01 77 ab 49 8d 7c 24 08 e8 37 5e d0 de 49 8b 6c 24 08 48 8d 7d 50 e8 e9 5c d0 de 8b 45 50 8d 50 ff 89 55 50 85 c0 75 86 <0f> 0b eb 82 0f 0b eb b3 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 [43929.458081] RSP: 0018:ffff888140f9f4b0 EFLAGS: 00010246 [43929.458086] RAX: 0000000000000000 RBX: ffff8881434f5288 RCX: dffffc0000000000 [43929.458090] RDX: 00000000ffffffff RSI: ffffffffa26d28a7 RDI: ffff88810ecc9550 [43929.458093] RBP: ffff88810ecc9500 R08: 0000000000000001 R09: ffffed10281f3e8f [43929.458096] R10: 0000000000000003 R11: ffff0000ffff0000 R12: ffff8881434f52a0 [43929.458100] R13: ffff888140f9f5f4 R14: ffff888151c7a800 R15: 0000000000000002 [43929.458103] FS: 00007f0c687c4740(0000) GS:ffff888390800000(0000) knlGS:0000000000000000 [43929.458107] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [43929.458111] CR2: 00007f58dbe5b008 CR3: 0000000123602005 CR4: 00000000001706f0 [43929.458114] Call Trace: [43929.458118] <TASK> [43929.458121] ? warn+0x9f/0x1a0 [43929.458127] ? nftsetelemdatadeactivate+0xe4/0xf0 [nftables] [43929.458188] ? reportbug+0x1b1/0x1e0 [43929.458196] ? handlebug+0x3c/0x70 [43929.458200] ? excinvalidop+0x17/0x40 [43929.458211] ? nftsetelemdatadeactivate+0xd7/0xf0 [nftables] [43929.458271] ? nftsetelemdatadeactivate+0xe4/0xf0 [nftables] [43929.458332] nftmapelemdeactivate+0x24/0x30 [nftables] [43929.458392] nftrhashwalk+0xdd/0x180 [nftables] [43929.458453] ? pfxnftrhashwalk+0x10/0x10 [nftables] [43929.458512] ? rbinsertcolor+0x2e/0x280 [43929.458520] nftmapdeactivate+0xdc/0x1e0 [nftables] [43929.458582] ? pfxnftmapdeactivate+0x10/0x10 [nftables] [43929.458642] ? pfxnftmapelemdeactivate+0x10/0x10 [nftables] [43929.458701] ? rcureadunlock+0x46/0x70 [43929.458709] nftdelset+0xff/0x110 [nftables] [43929.458769] nftflushtable+0x16f/0x460 [nftables] [43929.458830] nftablesdeltable+0x501/0x580 [nftables]
Other sources
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nftables: restore set elements when delete set fails
The Linux kernel CVE team has assigned CVE-2024-27012 to this issue.
Upstream advisory: https://lore.kernel.org/linux-cve-announce/2024050148-CVE-2024-27012-5564@gregkh/T
— Red Hat
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
debian/linuxto a version that resolves this vulnerability.Fixed in 6.12.27-1 - Upgrade
Upgrade
redhat/kernelto a version that resolves this vulnerability.Fixed in 6.8.8 - Upgrade
Upgrade
redhat/kernelto a version that resolves this vulnerability.Fixed in 6.9 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Patch CVE-2024-27012 - Compensating control
For nftables set deletion failures, ensure the kernel behavior is updated so delete-set failures restore set elements/refcounters by restoring the next generation bit and invoking nft_clear() from the .activate (abort) path, rather than relying on the existing iterator that skips inactive elements.
Event History
Frequently Asked Questions
What is the severity of CVE-2024-27012?
The severity of CVE-2024-27012 is currently classified as moderate.
How do I fix CVE-2024-27012?
To fix CVE-2024-27012, update your Linux kernel to version 6.8.8 or 6.9 or the recommended security patch provided by your distribution.
Which software versions are affected by CVE-2024-27012?
CVE-2024-27012 affects various versions of the Linux kernel between 6.4 and 6.8.8 and also version 6.9 in its release candidates.
Is CVE-2024-27012 exploitable remotely?
CVE-2024-27012 does not appear to be directly exploitable remotely, but attackers with local access may exploit it.
What could happen if I don't patch CVE-2024-27012?
Failure to patch CVE-2024-27012 could lead to potential instability or security risks in the Linux kernel's network filtering functionality.