From: Jason Gunthorpe Date: Tue, 16 Dec 2025 15:53:40 +0000 (-0400) Subject: iommufd/selftest: Check for overflow in IOMMU_TEST_OP_ADD_RESERVED X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e6a973af11135439de32ece3b9cbe3bfc043bea8;p=thirdparty%2Flinux.git iommufd/selftest: Check for overflow in IOMMU_TEST_OP_ADD_RESERVED syzkaller found it could overflow math in the test infrastructure and cause a WARN_ON by corrupting the reserved interval tree. This only effects test kernels with CONFIG_IOMMUFD_TEST. Validate the user input length in the test ioctl. Fixes: f4b20bb34c83 ("iommufd: Add kernel support for testing iommufd") Link: https://patch.msgid.link/r/0-v1-cd99f6049ba5+51-iommufd_syz_add_resv_jgg@nvidia.com Reviewed-by: Samiullah Khawaja Reviewed-by: Kevin Tian Tested-by: Yi Liu Reported-by: syzbot+57fdb0cf6a0c5d1f15a2@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/69368129.a70a0220.38f243.008f.GAE@google.com Signed-off-by: Jason Gunthorpe --- diff --git a/drivers/iommu/iommufd/selftest.c b/drivers/iommu/iommufd/selftest.c index 86446e153794..550ff36dec3a 100644 --- a/drivers/iommu/iommufd/selftest.c +++ b/drivers/iommu/iommufd/selftest.c @@ -1184,14 +1184,20 @@ static int iommufd_test_add_reserved(struct iommufd_ucmd *ucmd, unsigned int mockpt_id, unsigned long start, size_t length) { + unsigned long last; struct iommufd_ioas *ioas; int rc; + if (!length) + return -EINVAL; + if (check_add_overflow(start, length - 1, &last)) + return -EOVERFLOW; + ioas = iommufd_get_ioas(ucmd->ictx, mockpt_id); if (IS_ERR(ioas)) return PTR_ERR(ioas); down_write(&ioas->iopt.iova_rwsem); - rc = iopt_reserve_iova(&ioas->iopt, start, start + length - 1, NULL); + rc = iopt_reserve_iova(&ioas->iopt, start, last, NULL); up_write(&ioas->iopt.iova_rwsem); iommufd_put_object(ucmd->ictx, &ioas->obj); return rc;