Bug 2486999 (CVE-2026-46330)

Summary: CVE-2026-46330 kernel: Revert "net/smc: Introduce TCP ULP support"
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's TCP User-Level Protocol (ULP) support for SMC. This vulnerability arises when an active TCP socket is converted into an SMC socket, as the implementation attempts to modify core Virtual File System (VFS) structures in-place. This action violates fundamental VFS invariants, leading to a risk of use-after-free errors and general system instability.
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Description OSIDB Bzimport 2026-06-09 14:01:31 UTC 
In the Linux kernel, the following vulnerability has been resolved:

Revert "net/smc: Introduce TCP ULP support"

This reverts commit d7cd421da9da2cc7b4d25b8537f66db5c8331c40.

As reported by Al Viro, the TCP ULP support for SMC is fundamentally
broken. The implementation attempts to convert an active TCP socket
into an SMC socket by modifying the underlying `struct file`, dentry,
and inode in-place, which violates core VFS invariants that assume
these structures are immutable for an open file, creating a risk of
use after free errors and general system instability.

Given the severity of this design flaw and the fact that cleaner
alternatives (e.g., LD_PRELOAD, BPF) exist for legacy application
transparency, the correct course of action is to remove this feature
entirely.
Comment 1 Keith Grant 2026-06-09 16:38:57 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026060910-CVE-2026-46330-28d2@gregkh/T