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Amazon Linux AMI 2: CVE-2024-26737: Security patch for kernel (ALASKERNEL-5.15-2024-058)

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Amazon Linux AMI 2: CVE-2024-26737: Security patch for kernel (ALASKERNEL-5.15-2024-058)

Severity
4
CVSS
(AV:L/AC:M/Au:N/C:P/I:P/A:P)
Published
04/03/2024
Created
12/21/2024
Added
12/20/2024
Modified
12/20/2024

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix racing between bpf_timer_cancel_and_free and bpf_timer_cancel The following race is possible between bpf_timer_cancel_and_free and bpf_timer_cancel. It will lead a UAF on the timer->timer. bpf_timer_cancel(); spin_lock(); t = timer->time; spin_unlock(); bpf_timer_cancel_and_free(); spin_lock(); t = timer->timer; timer->timer = NULL; spin_unlock(); hrtimer_cancel(&t->timer); kfree(t); /* UAF on t */ hrtimer_cancel(&t->timer); In bpf_timer_cancel_and_free, this patch frees the timer->timer after a rcu grace period. This requires a rcu_head addition to the "struct bpf_hrtimer". Another kfree(t) happens in bpf_timer_init, this does not need a kfree_rcu because it is still under the spin_lock and timer->timer has not been visible by others yet. In bpf_timer_cancel, rcu_read_lock() is added because this helper can be used in a non rcu critical section context (e.g. from a sleepable bpf prog). Other timer->timer usages in helpers.c have been audited, bpf_timer_cancel() is the only place where timer->timer is used outside of the spin_lock. Another solution considered is to mark a t->flag in bpf_timer_cancel and clear it after hrtimer_cancel() is done.In bpf_timer_cancel_and_free, it busy waits for the flag to be cleared before kfree(t). This patch goes with a straight forward solution and frees timer->timer after a rcu grace period.

Solution(s)

  • amazon-linux-ami-2-upgrade-bpftool
  • amazon-linux-ami-2-upgrade-bpftool-debuginfo
  • amazon-linux-ami-2-upgrade-kernel
  • amazon-linux-ami-2-upgrade-kernel-debuginfo
  • amazon-linux-ami-2-upgrade-kernel-debuginfo-common-aarch64
  • amazon-linux-ami-2-upgrade-kernel-debuginfo-common-x86_64
  • amazon-linux-ami-2-upgrade-kernel-devel
  • amazon-linux-ami-2-upgrade-kernel-headers
  • amazon-linux-ami-2-upgrade-kernel-livepatch-5-15-152-100-162
  • amazon-linux-ami-2-upgrade-kernel-tools
  • amazon-linux-ami-2-upgrade-kernel-tools-debuginfo
  • amazon-linux-ami-2-upgrade-kernel-tools-devel
  • amazon-linux-ami-2-upgrade-perf
  • amazon-linux-ami-2-upgrade-perf-debuginfo
  • amazon-linux-ami-2-upgrade-python-perf
  • amazon-linux-ami-2-upgrade-python-perf-debuginfo

References

  • https://attackerkb.com/topics/cve-2024-26737
  • AL2/ALASKERNEL-5.15-2024-058
  • CVE - 2024-26737
  • 查看数 703
  • 已创建
  • 最后回复

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