CVE-2024-42109: netfilter: nf_tables: unconditionally flush pending work before notifier
First published: Tue Jul 30 2024(Updated: )
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: unconditionally flush pending work before notifier syzbot reports: KASAN: slab-uaf in nft_ctx_update include/net/netfilter/nf_tables.h:1831 KASAN: slab-uaf in nft_commit_release net/netfilter/nf_tables_api.c:9530 KASAN: slab-uaf int nf_tables_trans_destroy_work+0x152b/0x1750 net/netfilter/nf_tables_api.c:9597 Read of size 2 at addr ffff88802b0051c4 by task kworker/1:1/45 [..] Workqueue: events nf_tables_trans_destroy_work Call Trace: nft_ctx_update include/net/netfilter/nf_tables.h:1831 [inline] nft_commit_release net/netfilter/nf_tables_api.c:9530 [inline] nf_tables_trans_destroy_work+0x152b/0x1750 net/netfilter/nf_tables_api.c:9597 Problem is that the notifier does a conditional flush, but its possible that the table-to-be-removed is still referenced by transactions being processed by the worker, so we need to flush unconditionally. We could make the flush_work depend on whether we found a table to delete in nf-next to avoid the flush for most cases. AFAICS this problem is only exposed in nf-next, with commit e169285f8c56 ("netfilter: nf_tables: do not store nft_ctx in transaction objects"), with this commit applied there is an unconditional fetch of table->family which is whats triggering the above splat.
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Linux kernel | >=5.15.129<5.15.163 | |
| Linux Linux kernel | >=6.1.50<6.1.98 | |
| Linux Linux kernel | >=6.5<6.6.39 | |
| Linux Linux kernel | >=6.7<6.9.9 | |
| debian/linux | 5.10.223-1 5.10.226-1 6.1.115-1 6.1.112-1 6.11.9-1 6.11.10-1 |
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Reference Links
- https://git.kernel.org/stable/c/09e650c3a3a7d804430260510534ccbf71c75b2e
- https://git.kernel.org/stable/c/3325628cb36b7f216c5716e7b5124d9dc81199e4
- https://git.kernel.org/stable/c/4c06c13317b9a08decedcd7aaf706691e336277c
- https://git.kernel.org/stable/c/55a40406aac555defe9bdd0adec9508116ce7cb1
- https://git.kernel.org/stable/c/9f6958ba2e902f9820c594869bd710ba74b7c4c0
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-42109
- https://nvd.nist.gov/vuln/detail/CVE-2024-42109
- https://launchpad.net/bugs/cve/CVE-2024-42109
- https://security-tracker.debian.org/tracker/CVE-2024-42109
- https://ubuntu.com/security/CVE-2024-42109
- https://git.kernel.org/linus/9f6958ba2e902f9820c594869bd710ba74b7c4c0
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