CVE-2024-46786: fscache: delete fscache_cookie_lru_timer when fscache exits to avoid UAF
First published: Wed Sep 18 2024(Updated: )
In the Linux kernel, the following vulnerability has been resolved: fscache: delete fscache_cookie_lru_timer when fscache exits to avoid UAF The fscache_cookie_lru_timer is initialized when the fscache module is inserted, but is not deleted when the fscache module is removed. If timer_reduce() is called before removing the fscache module, the fscache_cookie_lru_timer will be added to the timer list of the current cpu. Afterwards, a use-after-free will be triggered in the softIRQ after removing the fscache module, as follows: ================================================================== BUG: unable to handle page fault for address: fffffbfff803c9e9 PF: supervisor read access in kernel mode PF: error_code(0x0000) - not-present page PGD 21ffea067 P4D 21ffea067 PUD 21ffe6067 PMD 110a7c067 PTE 0 Oops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G W 6.11.0-rc3 #855 Tainted: [W]=WARN RIP: 0010:__run_timer_base.part.0+0x254/0x8a0 Call Trace: <IRQ> tmigr_handle_remote_up+0x627/0x810 __walk_groups.isra.0+0x47/0x140 tmigr_handle_remote+0x1fa/0x2f0 handle_softirqs+0x180/0x590 irq_exit_rcu+0x84/0xb0 sysvec_apic_timer_interrupt+0x6e/0x90 </IRQ> <TASK> asm_sysvec_apic_timer_interrupt+0x1a/0x20 RIP: 0010:default_idle+0xf/0x20 default_idle_call+0x38/0x60 do_idle+0x2b5/0x300 cpu_startup_entry+0x54/0x60 start_secondary+0x20d/0x280 common_startup_64+0x13e/0x148 </TASK> Modules linked in: [last unloaded: netfs] ================================================================== Therefore delete fscache_cookie_lru_timer when removing the fscahe module.
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Linux kernel | >=5.17<6.6.51 | |
| Linux Linux kernel | >=6.7<6.10.10 | |
| Linux Linux kernel | =6.11-rc1 | |
| Linux Linux kernel | =6.11-rc2 | |
| Linux Linux kernel | =6.11-rc3 | |
| Linux Linux kernel | =6.11-rc4 | |
| Linux Linux kernel | =6.11-rc5 | |
| Linux Linux kernel | =6.11-rc6 | |
| debian/linux | <=6.1.115-1<=6.1.119-1 | 5.10.223-1 5.10.226-1 6.11.10-1 6.12.5-1 |
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Reference Links
- https://git.kernel.org/stable/c/0a11262549ac2ac6fb98c7cd40a67136817e5a52
- https://git.kernel.org/stable/c/72a6e22c604c95ddb3b10b5d3bb85b6ff4dbc34f
- https://git.kernel.org/stable/c/e0d724932ad12e3528f4ce97fc0f6078d0cce4bc
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-46786
- https://nvd.nist.gov/vuln/detail/CVE-2024-46786
- https://launchpad.net/bugs/cve/CVE-2024-46786
- https://security-tracker.debian.org/tracker/CVE-2024-46786
- https://ubuntu.com/security/CVE-2024-46786
- https://git.kernel.org/linus/72a6e22c604c95ddb3b10b5d3bb85b6ff4dbc34f
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