CVE-2024-42265: protect the fetch of ->fd[fd] in do_dup2() from mispredictions

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-08-17 · updated 2026-10-15

Description

In the Linux kernel, the following vulnerability has been resolved: protect the fetch of ->fd[fd] in do_dup2() from mispredictions both callers have verified that fd is not greater than ->max_fds; however, misprediction might end up with tofree = fdt->fd[fd]; being speculatively executed. That's wrong for the same reasons why it's wrong in close_fd()/file_close_fd_locked(); the same solution applies - array_index_nospec(fd, fdt->max_fds) could differ from fd only in case of speculative execution on mispredicted path.

Affected products

Linux kernel: before 4.19.320; from 4.20 before 5.4.282; from 5.5 before 5.10.224; from 5.11 before 5.15.165; from 5.16 before 6.1.104; from 6.2 before 6.6.45 — fixed in 4.19.320, 5.10.224, 5.15.165, 5.4.282, 6.1.104, 6.10.4

How to fix

Upgrade to a fixed version: Linux kernel 4.19.320, 5.10.224, 5.15.165, 5.4.282. Check the vendor advisory for mitigations.

References

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