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49e9c99f47
If the AFU descriptor of an AFU directed AFU indicates that it supports 0 maximum processes, we will accept that value and attempt to use it. The SPA will still be allocated (with 2 pages due to another minor bug and room for 958 processes), and when a context is allocated we will pass the value of 0 to idr_alloc as the maximum. However, idr_alloc will treat that as meaning no maximum and will allocate a context number and we return a valid context. Conceivably, this could lead to a buffer overflow of the SPA if more than 958 contexts were allocated, however this is mitigated by the fact that there are no known AFUs in the wild with a bogus AFU descriptor like this, and that only the root user is allowed to flash an AFU image to a card. Add a check when validating the AFU descriptor to reject any with 0 maximum processes. We do still allow a dedicated process only AFU to indicate that it supports 0 contexts even though that is forbidden in the architecture, as in that case we ignore the value and use 1 instead. This is just on the off-chance that such a dedicated process AFU may exist (not that I am aware of any), since their developers are less likely to have cared about this value at all. Signed-off-by: Ian Munsie <imunsie@au1.ibm.com> Reviewed-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com> Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>