Bug 2402296 (CVE-2023-53624) - CVE-2023-53624 kernel: net/sched: sch_fq: fix integer overflow of "credit"
Summary: CVE-2023-53624 kernel: net/sched: sch_fq: fix integer overflow of "credit"
Keywords:
Status: NEW
Alias: CVE-2023-53624
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2025-10-07 16:07 UTC by OSIDB Bzimport
Modified: 2025-10-14 23:43 UTC (History)
0 users

Fixed In Version:
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Description OSIDB Bzimport 2025-10-07 16:07:57 UTC
In the Linux kernel, the following vulnerability has been resolved:

net/sched: sch_fq: fix integer overflow of "credit"

if sch_fq is configured with "initial quantum" having values greater than
INT_MAX, the first assignment of "credit" does signed integer overflow to
a very negative value.
In this situation, the syzkaller script provided by Cristoph triggers the
CPU soft-lockup warning even with few sockets. It's not an infinite loop,
but "credit" wasn't probably meant to be minus 2Gb for each new flow.
Capping "initial quantum" to INT_MAX proved to fix the issue.

v2: validation of "initial quantum" is done in fq_policy, instead of open
    coding in fq_change() _ suggested by Jakub Kicinski


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