net/sched: fix potential stack infoleak in em_text_dump()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-98584
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-18 16:17:10 UTC
Updated2026-10-19 10:19:19 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: net/sched: fix potential stack infoleak in em_text_dump() em_text_dump() allocates struct tcf_em_text on the stack without zeroing it. strscpy() writes the algorithm name and a NUL terminator into conf.algo[], leaving the remaining bytes uninitialised. nla_put_nohdr() then copies the full struct to the netlink response. KMSAN on Linux 7.2-rc6 reports two kernel-infoleak splats from this path, one triggered via "tc filter show" and one via a raw RTM_GETTFILTER dump: BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x1c9/0x2620 nla_put_nohdr+0x83/0x130 em_text_dump+0x291/0x550 Local variable conf created at: em_text_dump+0x5d/0x550 Bytes 168-179 of 199 are uninitialized I am not certain whether this constitutes a real security problem in practice: the test was conducted in a controlled KMSAN environment and the leaked stack bytes may or may not carry sensitive data on actual production kernels. I am reporting it because KMSAN flagged it as a kernel-infoleak and the fix is straightforward. I can provide a userspace reproducer on request. The original code used strncpy() which zero-pads to the destination size. Commit b04202d6065c ("net/sched: replace strncpy with strscpy") replaced it with strscpy(), which does not pad, creating this condition. Zero-initialising the struct closes it.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected b04202d6065cba5dfd51fb9866400b25573eac67 9923e1c537f91f3530b52d4efce85f3d9c131bf8 git Not specified
CNA Linux Linux affected b04202d6065cba5dfd51fb9866400b25573eac67 0b160417826d22f24fc31a5b9cfae3b14aa70f76 git Not specified
CNA Linux Linux affected b04202d6065cba5dfd51fb9866400b25573eac67 9c572a83037a7dcd653ba3a9cc468c16b857d0c9 git Not specified
CNA Linux Linux affected 6.17 Not specified
CNA Linux Linux unaffected 6.17 semver Not specified
CNA Linux Linux unaffected 6.18.55 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.9 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/9923e1c537f91f3530b52d4efce85f3d9c131bf8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/0b160417826d22f24fc31a5b9cfae3b14aa70f76 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9c572a83037a7dcd653ba3a9cc468c16b857d0c9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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