From: Peiyang He Date: Thu, 9 Jul 2026 05:08:00 +0000 (+0800) Subject: iommufd: Reject DMABUF pages from the access pin path X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=5f3fc0ad9a41883a62098359b9fdbe4257f20e53;p=thirdparty%2Fkernel%2Flinux.git iommufd: Reject DMABUF pages from the access pin path DMABUF pages are not supported for iommufd access pinning. iommufd_access_pin_pages() returns struct page pointers for in-kernel CPU access, but DMABUF-backed iopt_pages do not carry a userspace address that can be passed to the GUP path. iopt_pages_rw_access() already rejects IOPT_ADDRESS_DMABUF before doing CPU access. Apply the same rejection to iopt_area_add_access() before it takes pages->mutex and calls iopt_pages_fill_xarray(). Otherwise a DMABUF-backed iopt_pages can reach the hole-fill path, where pfn_reader_user_pin() interprets the union as uptr and calls pin_user_pages_fast()/pin_user_pages_remote(). This fix also avoids the lockdep warning reported from that path, where pages_dmabuf_mutex_key is held while gup_fast_fallback() may acquire mmap_lock. Link: https://patch.msgid.link/r/CD68F549BF3761B7+20260709050800.520607-1-peiyang_he@smail.nju.edu.cn Reported-by: Peiyang He Closes: https://lore.kernel.org/all/E8540D7D05768C91+8b2ef227-3368-494e-909d-7b28e1489dfb@smail.nju.edu.cn/ Fixes: 71db84a092c3 ("iommufd: Add DMABUF to iopt_pages") Cc: stable@vger.kernel.org Tested-by: Peiyang He Signed-off-by: Peiyang He Reviewed-by: Kevin Tian Signed-off-by: Jason Gunthorpe --- diff --git a/drivers/iommu/iommufd/pages.c b/drivers/iommu/iommufd/pages.c index 03c8379bbc34..404f31d8f729 100644 --- a/drivers/iommu/iommufd/pages.c +++ b/drivers/iommu/iommufd/pages.c @@ -2451,6 +2451,9 @@ int iopt_area_add_access(struct iopt_area *area, unsigned long start_index, if ((flags & IOMMUFD_ACCESS_RW_WRITE) && !pages->writable) return -EPERM; + if (iopt_is_dmabuf(pages)) + return -EINVAL; + mutex_lock(&pages->mutex); access = iopt_pages_get_exact_access(pages, start_index, last_index); if (access) {