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Check that the frame pointer is within the current stack.

Authored by jhb on Nov 24 2020, 9:49 PM.



This same check is used on other architectures. Previously this would
permit a stack frame to unwind into any arbitrary kernel address
(including unmapped addresses).

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rS FreeBSD src repository - subversion
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jhb requested review of this revision.Nov 24 2020, 9:49 PM
91 ↗(On Diff #79958)

This was changed in rS333570 as unwind_frame could be probed by the FBT provider. It might be enough to exclude it from being probed in fbt_provide_module_function

91 ↗(On Diff #79958)

I think that would be fine. Alternately, perhaps unwind_frame() could move to stack.h?

91 ↗(On Diff #79958)

Hmm, risc-v would need the same approach as I have made it also use unwind_frame. Do you have a preference Mark on how to fix it?

91 ↗(On Diff #79958)

I think I prefer to explicitly exclude unwind_frame() from FBT by modifying fbt_provide_module_function() for the relevant arches. All of the solutions (keep the code as-is, make unwind_frame() inlinable, exclude unwind_frame() from FBT) are kind of fragile, but modifying FBT at least makes it easy to identify these problematic functions.

  • Add unwind_frame to fbt_excluded.
This revision was not accepted when it landed; it landed in state Needs Review.Dec 8 2020, 6:01 PM
This revision was automatically updated to reflect the committed changes.