Use After Free Affecting kernel-macros package, versions <5.14.21-150500.55.73.1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-SLES155-KERNELMACROS-7707125
- published17 Aug 2024
- disclosed16 Aug 2024
Introduced: 16 Aug 2024
CVE-2024-41070 (opens in a new tab)How to fix?
Upgrade SLES:15.5 kernel-macros to version 5.14.21-150500.55.73.1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-macros package and not the kernel-macros package as distributed by SLES.
See How to fix? for SLES:15.5 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
KVM: PPC: Book3S HV: Prevent UAF in kvm_spapr_tce_attach_iommu_group()
Al reported a possible use-after-free (UAF) in kvm_spapr_tce_attach_iommu_group().
It looks up stt from tablefd, but then continues to use it after doing
fdput() on the returned fd. After the fdput() the tablefd is free to be
closed by another thread. The close calls kvm_spapr_tce_release() and
then release_spapr_tce_table() (via call_rcu()) which frees stt.
Although there are calls to rcu_read_lock() in
kvm_spapr_tce_attach_iommu_group() they are not sufficient to prevent
the UAF, because stt is used outside the locked regions.
With an artifcial delay after the fdput() and a userspace program which triggers the race, KASAN detects the UAF:
BUG: KASAN: slab-use-after-free in kvm_spapr_tce_attach_iommu_group+0x298/0x720 [kvm] Read of size 4 at addr c000200027552c30 by task kvm-vfio/2505 CPU: 54 PID: 2505 Comm: kvm-vfio Not tainted 6.10.0-rc3-next-20240612-dirty #1 Hardware name: 8335-GTH POWER9 0x4e1202 opal:skiboot-v6.5.3-35-g1851b2a06 PowerNV Call Trace: dump_stack_lvl+0xb4/0x108 (unreliable) print_report+0x2b4/0x6ec kasan_report+0x118/0x2b0 __asan_load4+0xb8/0xd0 kvm_spapr_tce_attach_iommu_group+0x298/0x720 [kvm] kvm_vfio_set_attr+0x524/0xac0 [kvm] kvm_device_ioctl+0x144/0x240 [kvm] sys_ioctl+0x62c/0x1810 system_call_exception+0x190/0x440 system_call_vectored_common+0x15c/0x2ec ... Freed by task 0: ... kfree+0xec/0x3e0 release_spapr_tce_table+0xd4/0x11c [kvm] rcu_core+0x568/0x16a0 handle_softirqs+0x23c/0x920 do_softirq_own_stack+0x6c/0x90 do_softirq_own_stack+0x58/0x90 __irq_exit_rcu+0x218/0x2d0 irq_exit+0x30/0x80 arch_local_irq_restore+0x128/0x230 arch_local_irq_enable+0x1c/0x30 cpuidle_enter_state+0x134/0x5cc cpuidle_enter+0x6c/0xb0 call_cpuidle+0x7c/0x100 do_idle+0x394/0x410 cpu_startup_entry+0x60/0x70 start_secondary+0x3fc/0x410 start_secondary_prolog+0x10/0x14
Fix it by delaying the fdput() until stt is no longer in use, which
is effectively the entire function. To keep the patch minimal add a call
to fdput() at each of the existing return paths. Future work can convert
the function to goto or __cleanup style cleanup.
With the fix in place the test case no longer triggers the UAF.
References
- https://www.suse.com/security/cve/CVE-2024-41070.html
- https://bugzilla.suse.com/1228581
- https://git.kernel.org/stable/c/4cdf6926f443c84f680213c7aafbe6f91a5fcbc0
- https://git.kernel.org/stable/c/5f856023971f97fff74cfaf21b48ec320147b50a
- https://git.kernel.org/stable/c/82c7a4cf14aa866f8f7f09e662b02eddc49ee0bf
- https://git.kernel.org/stable/c/9975f93c760a32453d7639cf6fcf3f73b4e71ffe
- https://git.kernel.org/stable/c/a986fa57fd81a1430e00b3c6cf8a325d6f894a63
- https://git.kernel.org/stable/c/b26c8c85463ef27a522d24fcd05651f0bb039e47
- https://git.kernel.org/stable/c/be847bb20c809de8ac124431b556f244400b0491