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CVE-2021-47254

HIGHCVSS 7.8/10EPSS 0.24%

Last modified

CVE-2021-47254 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. In the Linux kernel, the following vulnerability has been resolved: gfs2: Fix use-after-free in gfs2_glock_shrink_scan The GLF_LRU flag is checked under lru_lock in gfs2_glock_remove_from_lru() to remove the glock from the lru list in __gfs2_glock_put(). On the shrink scan path, the same flag is cleared under lru_lock but because of cond_resched_lock(&lru_lock) in gfs2_dispose_glock_lru(), progress on the put side can be made without deleting the glock from the lru list. Keep GLF_LRU across the race window opened by cond_resched_lock(&lru_lock) to ensure correct behavior on both sides - clear GLF_LRU after list_del under lru_lock.. EPSS estimates a 0.24% chance of exploitation in the next 30 days.

Description

In the Linux kernel, the following vulnerability has been resolved: gfs2: Fix use-after-free in gfs2_glock_shrink_scan The GLF_LRU flag is checked under lru_lock in gfs2_glock_remove_from_lru() to remove the glock from the lru list in __gfs2_glock_put(). On the shrink scan path, the same flag is cleared under lru_lock but because of cond_resched_lock(&lru_lock) in gfs2_dispose_glock_lru(), progress on the put side can be made without deleting the glock from the lru list. Keep GLF_LRU across the race window opened by cond_resched_lock(&lru_lock) to ensure correct behavior on both sides - clear GLF_LRU after list_del under lru_lock.

Metrics

CVSS 3.1
7.8/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability
0.24%

15.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersionsUpdate
LinuxLinux Kernel>= 4.4.181, < 4.4.274—
LinuxLinux Kernel>= 4.9.180, < 4.9.274—
LinuxLinux Kernel>= 4.14.123, < 4.14.238—
LinuxLinux Kernel>= 4.19.47, < 4.19.196—
LinuxLinux Kernel>= 5.0.20, < 5.1—
LinuxLinux Kernel>= 5.1.6, < 5.4.127—
LinuxLinux Kernel>= 5.5, < 5.10.45—
LinuxLinux Kernel>= 5.11, < 5.12.12—
LinuxLinux Kernel5.13Rc1

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2021-47254?
In the Linux kernel, the following vulnerability has been resolved: gfs2: Fix use-after-free in gfs2_glock_shrink_scan The GLF_LRU flag is checked under lru_lock in gfs2_glock_remove_from_lru() to remove the glock from the lru list in __gfs2_glock_put(). On the shrink scan path, the same flag is cleared under lru_lock but because of cond_resched_lock(&lru_lock) in gfs2_dispose_glock_lru(), progress on the put side can be made without deleting the glock from the lru list. Keep GLF_LRU across the race window opened by cond_resched_lock(&lru_lock) to ensure correct behavior on both sides - clear GLF_LRU after list_del under lru_lock.
How severe is CVE-2021-47254?
CVE-2021-47254 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.24% probability of exploitation in the next 30 days.
How do I fix CVE-2021-47254?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-47254?

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Source: NVD / NIST