From df4bf3fa1b1e8d03380206fa027f956a62de517b Mon Sep 17 00:00:00 2001 From: Fedor Pchelkin Date: Wed, 9 Apr 2025 00:33:41 +0300 Subject: [PATCH] iommu: Fix crash in report_iommu_fault() The following crash is observed while handling an IOMMU fault with a recent kernel: kernel tried to execute NX-protected page - exploit attempt? (uid: 0) BUG: unable to handle page fault for address: ffff8c708299f700 PGD 19ee01067 P4D 19ee01067 PUD 101c10063 PMD 80000001028001e3 Oops: Oops: 0011 [#1] SMP NOPTI CPU: 4 UID: 0 PID: 139 Comm: irq/25-AMD-Vi Not tainted 6.15.0-rc1+ #20 PREEMPT(lazy) Hardware name: LENOVO 21D0/LNVNB161216, BIOS J6CN50WW 09/27/2024 RIP: 0010:0xffff8c708299f700 Call Trace: ? report_iommu_fault+0x78/0xd3 ? amd_iommu_report_page_fault+0x91/0x150 ? amd_iommu_int_thread+0x77/0x180 ? __pfx_irq_thread_fn+0x10/0x10 ? irq_thread_fn+0x23/0x60 ? irq_thread+0xf9/0x1e0 ? __pfx_irq_thread_dtor+0x10/0x10 ? __pfx_irq_thread+0x10/0x10 ? kthread+0xfc/0x240 ? __pfx_kthread+0x10/0x10 ? ret_from_fork+0x34/0x50 ? __pfx_kthread+0x10/0x10 ? ret_from_fork_asm+0x1a/0x30 report_iommu_fault() checks for an installed handler comparing the corresponding field to NULL. It can (and could before) be called for a domain with a different cookie type - IOMMU_COOKIE_DMA_IOVA, specifically. Cookie is represented as a union so we may end up with a garbage value treated there if this happens for a domain with another cookie type. Formerly there were two exclusive cookie types in the union. IOMMU_DOMAIN_SVA has a dedicated iommu_report_device_fault(). Call the fault handler only if the passed domain has a required cookie type. Found by Linux Verification Center (linuxtesting.org). Fixes: 6aa63a4ec947 ("iommu: Sort out domain user data") Signed-off-by: Fedor Pchelkin Reviewed-by: Kevin Tian Reviewed-by: Jason Gunthorpe Link: https://lore.kernel.org/r/20250408213342.285955-1-pchelkin@ispras.ru Signed-off-by: Joerg Roedel --- drivers/iommu/iommu.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index c8033ca66377..5729e8ecdda3 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -2717,7 +2717,8 @@ int report_iommu_fault(struct iommu_domain *domain, struct device *dev, * if upper layers showed interest and installed a fault handler, * invoke it. */ - if (domain->handler) + if (domain->cookie_type == IOMMU_COOKIE_FAULT_HANDLER && + domain->handler) ret = domain->handler(domain, dev, iova, flags, domain->handler_token); -- 2.25.1