efx_vfdi_set_status_page() validates the peer page count by
calculating the size of a request containing that many addresses and
comparing that with the maximum valid request size (4KB). The
calculation involves a multiplication that may overflow on a 32-bit
system.
We use kcalloc() to allocate memory to store the addresses; that also
does a multiplication and it does check for integer overflow, so any
values larger than 0x1fffffff will be rejected. However, values in
the range [0x1fffffffc, 0x1fffffff] pass boh tests and result in an
attempt to allocate nearly 4GB on the heap. This should be rejected
rather quickly as it's obviously impossible on a 32-bit system, and
indeed the maximum possible heap allocation is 32MB. Still, let's
make absolutely sure by fixing the initial validation.
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
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