[ Upstream commit 184233a5202786b20220acd2d04ddf909ef18f29 ] There are two issues here: 1) The "len" variable needs to be checked before the very first write. Otherwise if omap2_iommu_dump_ctx() with "bytes" less than 32 it is a buffer overflow. 2) The snprintf() function returns the number of bytes that *would* have been copied if there were enough space. But we want to know the number of bytes which were *actually* copied so use scnprintf() instead. Fixes: bd4396f09a4a ("iommu/omap: Consolidate OMAP IOMMU modules") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Robin Murphy <robin.murphy@arm.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Link: https://lore.kernel.org/r/YuvYh1JbE3v+abd5@kili Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Sasha Levin <sashal@kernel.org>