The patch below does not apply to the 6.6-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-6.6.y git checkout FETCH_HEAD git cherry-pick -x cf7c2789822db8b5efa34f5ebcf1621bc0008d48 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024030407-headway-blustery-23f1@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

cf7c2789822d ("iommufd: Fix protection fault in iommufd_test_syz_conv_iova") bd7a282650b8 ("iommufd: Add iommufd_ctx to iommufd_put_object()") 65fe32f7a447 ("iommufd/selftest: Add nested domain allocation for mock domain") 2bdabb8e82f5 ("iommu: Pass in parent domain with user_data to domain_alloc_user op") b5021cb264e6 ("iommufd: Share iommufd_hwpt_alloc with IOMMUFD_OBJ_HWPT_NESTED") 89db31635c87 ("iommufd: Derive iommufd_hwpt_paging from iommufd_hw_pagetable") 58d84f430dc7 ("iommufd/device: Wrap IOMMUFD_OBJ_HWPT_PAGING-only configurations") 9744a7ab62cc ("iommufd: Rename IOMMUFD_OBJ_HW_PAGETABLE to IOMMUFD_OBJ_HWPT_PAGING") 2ccabf81ddff ("iommufd: Only enforce cache coherency in iommufd_hw_pagetable_alloc") a9af47e382a4 ("iommufd/selftest: Test IOMMU_HWPT_GET_DIRTY_BITMAP") 7adf267d66d1 ("iommufd/selftest: Test IOMMU_HWPT_SET_DIRTY_TRACKING") 266ce58989ba ("iommufd/selftest: Test IOMMU_HWPT_ALLOC_DIRTY_TRACKING") e04b23c8d4ed ("iommufd/selftest: Expand mock_domain with dev_flags") 421a511a293f ("iommu/amd: Access/Dirty bit support in IOPTEs") 134288158a41 ("iommu/amd: Add domain_alloc_user based domain allocation") b9a60d6f850e ("iommufd: Add IOMMU_HWPT_GET_DIRTY_BITMAP") e2a4b2947849 ("iommufd: Add IOMMU_HWPT_SET_DIRTY_TRACKING") 5f9bdbf4c658 ("iommufd: Add a flag to enforce dirty tracking on attach") 750e2e902b71 ("iommu: Add iommu_domain ops for dirty tracking") b5f9e63278d6 ("iommufd: Correct IOMMU_HWPT_ALLOC_NEST_PARENT description")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From cf7c2789822db8b5efa34f5ebcf1621bc0008d48 Mon Sep 17 00:00:00 2001 From: Nicolin Chen nicolinc@nvidia.com Date: Thu, 22 Feb 2024 13:23:47 -0800 Subject: [PATCH] iommufd: Fix protection fault in iommufd_test_syz_conv_iova

Syzkaller reported the following bug:

general protection fault, probably for non-canonical address 0xdffffc0000000038: 0000 [#1] SMP KASAN KASAN: null-ptr-deref in range [0x00000000000001c0-0x00000000000001c7] Call Trace: lock_acquire lock_acquire+0x1ce/0x4f0 down_read+0x93/0x4a0 iommufd_test_syz_conv_iova+0x56/0x1f0 iommufd_test_access_rw.isra.0+0x2ec/0x390 iommufd_test+0x1058/0x1e30 iommufd_fops_ioctl+0x381/0x510 vfs_ioctl __do_sys_ioctl __se_sys_ioctl __x64_sys_ioctl+0x170/0x1e0 do_syscall_x64 do_syscall_64+0x71/0x140

This is because the new iommufd_access_change_ioas() sets access->ioas to NULL during its process, so the lock might be gone in a concurrent racing context.

Fix this by doing the same access->ioas sanity as iommufd_access_rw() and iommufd_access_pin_pages() functions do.

Cc: stable@vger.kernel.org Fixes: 9227da7816dd ("iommufd: Add iommufd_access_change_ioas(_id) helpers") Link: https://lore.kernel.org/r/3f1932acaf1dd494d404c04364d73ce8f57f3e5e.170863662... Reported-by: Jason Gunthorpe jgg@nvidia.com Signed-off-by: Nicolin Chen nicolinc@nvidia.com Reviewed-by: Kevin Tian kevin.tian@intel.com Signed-off-by: Jason Gunthorpe jgg@nvidia.com

diff --git a/drivers/iommu/iommufd/selftest.c b/drivers/iommu/iommufd/selftest.c index 2bfe77bd351d..d59e199a8705 100644 --- a/drivers/iommu/iommufd/selftest.c +++ b/drivers/iommu/iommufd/selftest.c @@ -63,8 +63,8 @@ enum { * In syzkaller mode the 64 bit IOVA is converted into an nth area and offset * value. This has a much smaller randomization space and syzkaller can hit it. */ -static unsigned long iommufd_test_syz_conv_iova(struct io_pagetable *iopt, - u64 *iova) +static unsigned long __iommufd_test_syz_conv_iova(struct io_pagetable *iopt, + u64 *iova) { struct syz_layout { __u32 nth_area; @@ -88,6 +88,21 @@ static unsigned long iommufd_test_syz_conv_iova(struct io_pagetable *iopt, return 0; }

+static unsigned long iommufd_test_syz_conv_iova(struct iommufd_access *access, + u64 *iova) +{ + unsigned long ret; + + mutex_lock(&access->ioas_lock); + if (!access->ioas) { + mutex_unlock(&access->ioas_lock); + return 0; + } + ret = __iommufd_test_syz_conv_iova(&access->ioas->iopt, iova); + mutex_unlock(&access->ioas_lock); + return ret; +} + void iommufd_test_syz_conv_iova_id(struct iommufd_ucmd *ucmd, unsigned int ioas_id, u64 *iova, u32 *flags) { @@ -100,7 +115,7 @@ void iommufd_test_syz_conv_iova_id(struct iommufd_ucmd *ucmd, ioas = iommufd_get_ioas(ucmd->ictx, ioas_id); if (IS_ERR(ioas)) return; - *iova = iommufd_test_syz_conv_iova(&ioas->iopt, iova); + *iova = __iommufd_test_syz_conv_iova(&ioas->iopt, iova); iommufd_put_object(ucmd->ictx, &ioas->obj); }

@@ -1161,7 +1176,7 @@ static int iommufd_test_access_pages(struct iommufd_ucmd *ucmd, }

if (flags & MOCK_FLAGS_ACCESS_SYZ) - iova = iommufd_test_syz_conv_iova(&staccess->access->ioas->iopt, + iova = iommufd_test_syz_conv_iova(staccess->access, &cmd->access_pages.iova);

npages = (ALIGN(iova + length, PAGE_SIZE) - @@ -1263,8 +1278,8 @@ static int iommufd_test_access_rw(struct iommufd_ucmd *ucmd, }

if (flags & MOCK_FLAGS_ACCESS_SYZ) - iova = iommufd_test_syz_conv_iova(&staccess->access->ioas->iopt, - &cmd->access_rw.iova); + iova = iommufd_test_syz_conv_iova(staccess->access, + &cmd->access_rw.iova);

rc = iommufd_access_rw(staccess->access, iova, tmp, length, flags); if (rc)