CVE-2026-93061: gpu: host1x: Avoid stack over-read in debug output helpers
In the Linux kernel, the following vulnerability has been resolved:
gpu: host1x: Avoid stack over-read in debug output helpers
host1xdebugoutput() and host1xdebugcont() used vsnprintf(), which returns the length the formatted string would have reached with an unbounded buffer. That return value was passed straight to o->fn as the number of bytes to emit.
This could cause a read past end of the output buffer if a call to host1xdebug produced a string longer than 256 bytes. This only affected the debugfs files as the printk debug sink ignores the number of bytes. In practice, this is very unlikely to occur.
Fix by switching to vscnprintf(), which returns the number of bytes actually written.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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debian/linuxto a version that resolves this vulnerability.Fixed in 6.1.190-1Fixed in 6.12.115-2Fixed in 7.2.12-1Fixed in 7.2.15-1 - 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 - Compensating control
In the Linux kernel host1x debug output helpers, switch host1x_debug_output() and host1x_debug_cont() from vsnprintf() to vscnprintf(), which returns the number of bytes actually written.
Event History
Frequently Asked Questions
Which interfaces are affected by this issue?
Only the host1x debugfs files are affected. The printk debug sink ignores the byte count and is not affected by this behavior.
What condition is required to trigger the over-read?
A call to host1x_debug_output() or host1x_debug_cont() must produce formatted output longer than 256 bytes. The oversized length returned by vsnprintf() could then be used to emit bytes beyond the output buffer.
How likely is this to occur in practice?
The available information states that this is very unlikely to occur in practice.
What change resolves the issue?
The fix replaces vsnprintf() with vscnprintf() in the affected debug output helpers, so the emitted length reflects the bytes actually written to the buffer.