posix-cpu-timers: Use u64 multiplication in update_rlimit_cpu()
Published Aug 15, 2026
5.5
MEDIUMCVSS 3.1
EPSS 0.22%
Description
update_rlimit_cpu() converts the RLIMIT_CPU value to nanoseconds with
u64 nsecs = rlim_new * NSEC_PER_SEC;
On 32-bit kernels both rlim_new (unsigned long) and NSEC_PER_SEC (1000000000L) are 32-bit, so the multiplication is performed in unsigned long and truncated for rlim_new > 4 seconds before being widened to u64.
The same file already casts to u64 for the matching computation in check_process_timers():
u64 softns = (u64)soft * NSEC_PER_SEC;
As a result, the truncated value is installed into the CPUCLOCK_PROF expiry cache (nextevt), causing the process CPU timer to be programmed to fire prematurely for any RLIMIT_CPU soft limit >= 5 seconds. The actual SIGXCPU/SIGKILL decision in check_process_timers() already casts to u64 and is therefore correct, so limit enforcement is not broken; only the expiry-cache programming is wrong. Apply the same cast here so both paths convert rlim_cur identically.
64-bit kernels are unaffected.
Affected products
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- Version StatusaffectedConstraints
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- Version
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- Version 4.11StatusaffectedConstraints-
- Version 0StatusunaffectedConstraints<4.11
- Version 5.10.261StatusunaffectedConstraints<=5.10.*
- Version 5.15.212StatusunaffectedConstraints<=5.15.*
- Version 6.1.178StatusunaffectedConstraints<=6.1.*
- Version 6.12.97StatusunaffectedConstraints<=6.12.*
- Version 6.18.40StatusunaffectedConstraints<=6.18.*
- Version 6.6.145StatusunaffectedConstraints<=6.6.*
- Version 7.1.5StatusunaffectedConstraints<=7.1.*
- Version 7.2StatusunaffectedConstraints<=*
- Version
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
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| Linux | Linux | affected |
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No data.
No data.
Red Hat Enterprise Linux 10
kernel
Fix deferred
Red Hat Enterprise Linux 6
kernel
Not affected
Red Hat Enterprise Linux 7
kernel
Not affected
Red Hat Enterprise Linux 7
kernel-rt
Not affected
Red Hat Enterprise Linux 8
kernel
Fix deferred
Red Hat Enterprise Linux 8
kernel-rt
Fix deferred
Red Hat Enterprise Linux 9
kernel
Fix deferred
Red Hat Enterprise Linux 9
kernel-rt
Fix deferred
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 10 | kernel | Fix deferred | n/a |
| Red Hat Enterprise Linux 6 | kernel | Not affected | n/a |
| Red Hat Enterprise Linux 7 | kernel | Not affected | n/a |
| Red Hat Enterprise Linux 7 | kernel-rt | Not affected | n/a |
| Red Hat Enterprise Linux 8 | kernel | Fix deferred | n/a |
| Red Hat Enterprise Linux 8 | kernel-rt | Fix deferred | n/a |
| Red Hat Enterprise Linux 9 | kernel | Fix deferred | n/a |
| Red Hat Enterprise Linux 9 | kernel-rt | Fix deferred | n/a |
No package ranges for this CVE.
Remediation
No remediation recorded yet.
References (13)
- https://access.redhat.com/security/cve/CVE-2026-72068 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2516242 Issue Tracking
- https://git.kernel.org/stable/c/1fafc4d9b411645eb34de43362b966dc8fb3e263
- https://git.kernel.org/stable/c/26aff38fefb1d6cd87e22525f41cc8f1aa61b24f
- https://git.kernel.org/stable/c/384628d6cdde0fcd76868606fad3ad8293100afb
- https://git.kernel.org/stable/c/571e1f10b5996ba3e4dc63ea77de4aa309c384ce
- https://git.kernel.org/stable/c/cff8281bacd2866767e6194c3079d33b6c5a74f4
- https://git.kernel.org/stable/c/ea6a188ee805e841a0e242f14d15953e0dfa74bb
- https://git.kernel.org/stable/c/edf6babb9edd2d3e19229ade339081f439d4f478
- https://git.kernel.org/stable/c/feb5c87c8514444ba891b75a5a3eae57c64edaf8
- https://lore.kernel.org/linux-cve-announce/2026081518-CVE-2026-72068-23e7@gregkh/T
- https://nvd.nist.gov/vuln/detail/CVE-2026-72068
- https://www.cve.org/CVERecord?id=CVE-2026-72068
Change history (0)
No recorded changes yet.