CVE-2024-49936: net/xen-netback: prevent UAF in xenvif_flush_hash()
In the Linux kernel, the following vulnerability has been resolved:
net/xen-netback: prevent UAF in xenvifflushhash()
During the listforeachentryrcu iteration call of xenvifflushhash, kfreercu does not exist inside the rcu read critical section, so if kfreercu is called when the rcu grace period ends during the iteration, UAF occurs when accessing head->next after the entry becomes free.
Therefore, to solve this, you need to change it to listforeachentrysafe.
Other sources
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— Launchpad
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
debian/linuxto a version that resolves this vulnerability.Fixed in 5.10.234-1Fixed in 6.1.129-1Fixed in 6.1.135-1Fixed in 6.12.25-1Fixed in 6.12.27-1 - Upgrade
Upgrade
debian/linux-6.1to a version that resolves this vulnerability.Fixed in 6.1.129-1~deb11u1 - Configuration
In net/xen-netback, update xenvif_flush_hash() to use list_for_each_entry_safe rather than list_for_each_entry_rcu to prevent UAF when kfree_rcu behavior occurs around the RCU grace period ending during iteration.
Linux kernel (net/xen-netback) list_for_each_entry_rcu -> list_for_each_entry_safe = Use list_for_each_entry_safe in xenvif_flush_hash instead of list_for_each_entry_rcu
Event History
Frequently Asked Questions
What is the severity of CVE-2024-49936?
CVE-2024-49936 has a severity rating that could potentially lead to a use-after-free condition in the Linux kernel.
How do I fix CVE-2024-49936?
To address CVE-2024-49936, update your Linux kernel to a version that is patched, specifically versions 6.1.123-1 or later.
Which versions of the Linux kernel are affected by CVE-2024-49936?
CVE-2024-49936 affects several Linux kernel versions including those between 5.10.227 and 6.11.3.
What component of the Linux kernel is affected by CVE-2024-49936?
CVE-2024-49936 impacts the net/xen-netback component, particularly the xenvif_flush_hash function.
Is CVE-2024-49936 a critical vulnerability?
CVE-2024-49936 is considered a critical vulnerability due to its potential to cause serious security issues if exploited.