CVE-2026-98593: s390/debug: Fix NULL pointer dereference in debug_info_copy()
In the Linux kernel, the following vulnerability has been resolved:
s390/debug: Fix NULL pointer dereference in debuginfocopy()
When debugregisterstatic() fails, it clears areas, activepages and activeentries but leaves the area bounds unchanged. Copying such an area, either by opening its view file or via debugdump(), makes debuginfocopy() dereference the NULL pointers.
Skip the copy loop when the source has no areas.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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Fixed in 6.6.159.1-1 - Upgrade
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ubuntu/linux-aws-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1119.126~20.04.1 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1016.17 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1
Event History
Frequently Asked Questions
What condition is required to trigger the NULL pointer dereference?
The condition occurs after debug_register_static() fails and clears the debug area's areas, active_pages, and active_entries pointers while leaving its area bounds unchanged. A subsequent copy of that area through its view file or debug_dump() can dereference the cleared pointers.
Which interfaces can cause the affected copy operation?
Opening the affected debug area's view file can invoke the copy operation. Calling debug_dump() on the area can also trigger it.
What mitigation is available if the fix cannot be applied immediately?
Avoid copying debug areas whose debug_register_static() call has failed, including avoiding access to their view files and avoiding debug_dump() for those areas.