Commit d3e3d2be authored Jun 02, 2020 by Robin Murphy Committed by Joerg Roedel Jun 30, 2020

iommu/iova: Don't BUG on invalid PFNs



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>
Reviewed-by: Prakash Gupta <guptap@codeaurora.org>
Link: https://lore.kernel.org/r/acbd2d092b42738a03a21b417ce64e27f8c91c86.1591103298.git.robin.murphy@arm.com


Signed-off-by: Joerg Roedel <jroedel@suse.de>

parent 9ebcfadb

drivers/iommu/iova.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -811,7 +811,9 @@ iova_magazine_free_pfns(struct iova_magazine mag, struct iova_domain iovad)
		for (i = 0 ; i < mag->size; ++i) {
		struct iova *iova = private_find_iova(iovad, mag->pfns[i]);

		BUG_ON(!iova);
		if (WARN_ON(!iova))
		continue;

		private_free_iova(iovad, iova);
		}

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