Re: [PATCH] iommu/iova: Don't BUG on invalid PFNs

Joerg Roedel
2020-06-30T08:42:58Z

On Tue, Jun 02, 2020 at 02:08:18PM +0100, Robin Murphy wrote:
> Unlike the other instances which represent a complete loss of
> consistency within the rcache mechanism itself, or a fundamental
> and obvious misconfiguration by an IOMMU driver, the BUG_ON() in
> iova_magazine_free_pfns() can be provoked at more or less any time
> in a "spooky action-at-a-distance" manner by any old device driver
> passing nonsense to dma_unmap_*() which then propagates through to
> queue_iova().
>
> Not only is this well outside the IOVA layer's control, it's also
> nowhere near fatal enough to justify panicking anyway - all that
> really achieves is to make debugging the offending driver more
> difficult. Let's simply WARN and otherwise ignore bogus PFNs.
>
> Reported-by: Prakash Gupta <guptap@codeaurora.org>
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> ---
> drivers/iommu/iova.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)

Applied without stable tag, thanks.