CVE-2024-56755: netfs/fscache: Add a memory barrier for FSCACHE_VOLUME_CREATING
In the Linux kernel, the following vulnerability has been resolved:
netfs/fscache: Add a memory barrier for FSCACHEVOLUMECREATING
In fscachecreatevolume(), there is a missing memory barrier between the bit-clearing operation and the wake-up operation. This may cause a situation where, after a wake-up, the bit-clearing operation hasn't been detected yet, leading to an indefinite wait. The triggering process is as follows:
[cookie1] [cookie2] [volumework] fscacheperformlookup fscachecreatevolume fscacheperformlookup fscachecreatevolume fscachecreatevolumework cachefilesacquirevolume clearandwakeupbit testandsetbit testandsetbit goto maybewait goto nowait
In the above process, cookie1 and cookie2 has the same volume. When cookie1 enters the -nowait- process, it will clear the bit and wake up the waiting process. If a barrier is missing, it may cause cookie2 to remain in the -wait- process indefinitely.
In commit 3288666c7256 ("fscache: Use clearandwakeupbit() in fscachecreatevolumework()"), barriers were added to similar operations in fscachecreatevolumework(), but fscachecreatevolume() was missed.
By combining the clear and wake operations into clearandwakeupbit() to fix this issue.
Other sources
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— Launchpad
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2024-56755?
CVE-2024-56755 has been rated as a medium severity vulnerability in the Linux kernel.
How do I fix CVE-2024-56755?
To fix CVE-2024-56755, ensure that you update the Linux kernel to the latest patched version that addresses this vulnerability.
Which Linux kernel versions are affected by CVE-2024-56755?
CVE-2024-56755 affects Linux kernel versions between 5.17 to 6.1.120, 6.2 to 6.6.64, 6.7 to 6.11.11, and 6.12 to 6.12.2.
What component is primarily affected by CVE-2024-56755?
CVE-2024-56755 primarily affects the netfs/fscache subsystem of the Linux kernel.
What type of vulnerability is CVE-2024-56755?
CVE-2024-56755 is a synchronization issue due to a missing memory barrier in the fscache_create_volume() function.