CVE - CVE-2025-21647

CVE-ID
CVE-2025-21647	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
Description
In the Linux kernel, the following vulnerability has been resolved: sched: sch_cake: add bounds checks to host bulk flow fairness counts Even though we fixed a logic error in the commit cited below, syzbot still managed to trigger an underflow of the per-host bulk flow counters, leading to an out of bounds memory access. To avoid any such logic errors causing out of bounds memory accesses, this commit factors out all accesses to the per-host bulk flow counters to a series of helpers that perform bounds-checking before any increments and decrements. This also has the benefit of improving readability by moving the conditional checks for the flow mode into these helpers, instead of having them spread out throughout the code (which was the cause of the original logic error). As part of this change, the flow quantum calculation is consolidated into a helper function, which means that the dithering applied to the ost load scaling is now applied both in the DRR rotation and when a sparse flow's quantum is first initiated. The only user-visible effect of this is that the maximum packet size that can be sent while a flow stays sparse will now vary with +/- one byte in some cases. This should not make a noticeable difference in practice, and thus it's not worth complicating the code to preserve the old behaviour.
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
MISC:https://git.kernel.org/stable/c/27202e2e8721c3b23831563c36ed5ac7818641ba URL:https://git.kernel.org/stable/c/27202e2e8721c3b23831563c36ed5ac7818641ba MISC:https://git.kernel.org/stable/c/737d4d91d35b5f7fa5bb442651472277318b0bfd URL:https://git.kernel.org/stable/c/737d4d91d35b5f7fa5bb442651472277318b0bfd MISC:https://git.kernel.org/stable/c/91bb18950b88f955838ec0c1d97f74d135756dc7 URL:https://git.kernel.org/stable/c/91bb18950b88f955838ec0c1d97f74d135756dc7 MISC:https://git.kernel.org/stable/c/a777e06dfc72bed73c05dcb437d7c27ad5f90f3f URL:https://git.kernel.org/stable/c/a777e06dfc72bed73c05dcb437d7c27ad5f90f3f
Assigning CNA
kernel.org
Date Record Created
20241229	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20241229)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
This is an record on the CVE List, which provides common identifiers for publicly known cybersecurity vulnerabilities.
Search CVE Using Keywords: You can also search by reference using the CVE Reference Maps.
For More Information: CVE Request Web Form (select "Other" from dropdown)