The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x cb30dfa75d55eced379a42fd67bd5fb7ec38555e # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025110935-stylist-chastise-3700@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From cb30dfa75d55eced379a42fd67bd5fb7ec38555e Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe jgg@ziepe.ca Date: Wed, 8 Oct 2025 15:17:18 -0300 Subject: [PATCH] iommufd: Don't overflow during division for dirty tracking
If pgshift is 63 then BITS_PER_TYPE(*bitmap->bitmap) * pgsize will overflow to 0 and this triggers divide by 0.
In this case the index should just be 0, so reorganize things to divide by shift and avoid hitting any overflows.
Link: https://patch.msgid.link/r/0-v1-663679b57226+172-iommufd_dirty_div0_jgg@nvid... Cc: stable@vger.kernel.org Fixes: 58ccf0190d19 ("vfio: Add an IOVA bitmap support") Reviewed-by: Joao Martins joao.m.martins@oracle.com Reviewed-by: Nicolin Chen nicolinc@nvidia.com Reviewed-by: Kevin Tian kevin.tian@intel.com Reported-by: syzbot+093a8a8b859472e6c257@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=093a8a8b859472e6c257 Signed-off-by: Jason Gunthorpe jgg@nvidia.com
diff --git a/drivers/iommu/iommufd/iova_bitmap.c b/drivers/iommu/iommufd/iova_bitmap.c index 4514575818fc..b5b67a9d3fb3 100644 --- a/drivers/iommu/iommufd/iova_bitmap.c +++ b/drivers/iommu/iommufd/iova_bitmap.c @@ -130,9 +130,8 @@ struct iova_bitmap { static unsigned long iova_bitmap_offset_to_index(struct iova_bitmap *bitmap, unsigned long iova) { - unsigned long pgsize = 1UL << bitmap->mapped.pgshift; - - return iova / (BITS_PER_TYPE(*bitmap->bitmap) * pgsize); + return (iova >> bitmap->mapped.pgshift) / + BITS_PER_TYPE(*bitmap->bitmap); }
/*