[Bug 206585] hpt_set_info possible buffer overflow

bugzilla-noreply at freebsd.org bugzilla-noreply at freebsd.org
Sun Jan 24 17:57:25 UTC 2016


https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=206585

            Bug ID: 206585
           Summary: hpt_set_info possible buffer overflow
           Product: Base System
           Version: 11.0-CURRENT
          Hardware: Any
                OS: Any
            Status: New
          Severity: Affects Only Me
          Priority: ---
         Component: kern
          Assignee: freebsd-bugs at FreeBSD.org
          Reporter: ecturt at gmail.com

In `hpt_status` -> `hpt_set_info`, `nOutBufferSize` and `nInBufferSize` are
checked at the same time, but not individually:

if (piop->nInBufferSize+piop->nOutBufferSize > PAGE_SIZE) {
        KdPrintE(("User buffer too large\n"));
        return -EINVAL;
}

Before performing a kernel allocation:

ke_area = malloc(piop->nInBufferSize+piop->nOutBufferSize, M_DEVBUF, M_NOWAIT);

However, the sizes are later used individually for some copies:

if (piop->nInBufferSize)
        copyin((void*)(ULONG_PTR)piop->lpInBuffer, ke_area,
piop->nInBufferSize);

...

if (piop->nOutBufferSize)
        copyout(ke_area + piop->nInBufferSize,
(void*)(ULONG_PTR)piop->lpOutBuffer, piop->nOutBufferSize);

It might be possible for `nInBufferSize`, or `outBufferSize`, or both, to be
large enough for `piop->nInBufferSize+piop->nOutBufferSize` to overflow and be
less than `PAGE_SIZE`.

In this situation the copy calls would result in a heap overflow.

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