Service interruption via unchecked blk_iocost shift exponent
Published Oct 21, 2024 · Updated May 11, 2026
Undefined shift behavior in the Linux kernel blk_iocost controller allows local users to interrupt service through I/O cost activity. ioc_forgive_debts() uses an exponent derived from debt calculations in two u64 shift operations without first limiting it to 63 bits. Triggering requires local low-privileged access, and the upstream record reports UBSAN faults without identifying a demonstrated consequence beyond the undefined operation.
Summary
What happened
Undefined shift behavior in the Linux kernel blk_iocost controller allows local users to interrupt service through I/O cost activity. ioc_forgive_debts() uses an exponent derived from debt calculations in two u64 shift operations without first limiting it to 63 bits. Triggering requires local low-privileged access, and the upstream record reports UBSAN faults without identifying a demonstrated consequence beyond the undefined operation.
The record
- CVE
- CVE-2024-49933
- Published
- Oct 21, 2024
- Updated
- May 11, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1499
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Oct 21, 2024CVE publishedPublication date reported by the CVE source.
- May 11, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=5.10
- Affected versionversion=bec02dbbafad534674309f8b948094900f456797 <1ab2cfe19700fb3dde4c7dfec392acff34db3120
- Affected versionversion=bec02dbbafad534674309f8b948094900f456797 <1b120f151871eb47ce9f283c007af3f8ae1d990e
- Affected versionversion=bec02dbbafad534674309f8b948094900f456797 <1f61d509257d6a05763d05bf37943b35306522b1
- Affected versionversion=bec02dbbafad534674309f8b948094900f456797 <364022095bdd4108efdaaa68576afa4712a5d085
- Affected versionversion=bec02dbbafad534674309f8b948094900f456797 <59121bb38fdc01434ea3fe361ee02b59f036227f
- Affected versionversion=bec02dbbafad534674309f8b948094900f456797 <9bce8005ec0dcb23a58300e8522fe4a31da606fa
- Affected versionversion=bec02dbbafad534674309f8b948094900f456797 <f4ef9bef023d5c543cb0f3194ecacfd47ef590ec
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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