On Tue, Apr 28, 2020 at 2:05 PM Jeremy Kerr [off-list ref] wrote:

Currently, we may perform a copy_to_user (through
simple_read_from_buffer()) while holding a context's register_lock,
while accessing the context save area.

This change uses a temporary buffers for the context save area data,
which we then pass to simple_read_from_buffer.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
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Thanks for fixing this!

I wonder how far it should be backported, given that this has been broken for
14 years now.

Fixes: bf1ab978be23 ("[POWERPC] coredump: Add SPU elf notes to coredump.")
Reviewed-by: Arnd Bergmann <arnd@arndb.de>