xhci: prevent a theoretical endless loop while preparing rings.

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xhci driver links together segments in a ring buffer by turning the last
TRB of a segment into a link TRB, pointing to the beginning of
the next segment.

If the first TRB of every segment for some unknown reason is a link TRB
pointing to the next segment, then prepare_ring() loops indefinitely.
This isn't something the xhci driver would do.
xHC hardware has access to these rings, it sholdn't be writing link
TRBs either, but with broken xHC hardware this could in theory be
possible.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20210129130044.206855-10-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Mathias Nyman 2021-01-29 15:00:26 +02:00 • committed by Greg Kroah-Hartman

parent c089cadaa0

commit 04d21f7219

1 changed files with 7 additions and 0 deletions

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drivers/usb/host/xhci-ring.c

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