iommu_mock_device_add() first calls iommu_fwspec_init(), which on
success allocates both dev->iommu (via dev_iommu_get()) and
dev->iommu->fwspec. If the subsequent device_add(dev) call fails,
the error path only calls iommu_fwspec_free(dev), which frees
fwspec but leaves dev->iommu still allocated.

This triggers the following kmemleak report when fuzzing with Syzkaller:

BUG: memory leak
unreferenced object 0xffff888011e0a200 (size 192):
  comm "syz.1.1695", pid 24885, jiffies 4295222527
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 ad 4e ad de  .............N..
    ff ff ff ff 00 00 00 00 ff ff ff ff ff ff ff ff  ................
  backtrace (crc 25df5bb3):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4575 [inline]
    slab_alloc_node mm/slub.c:4899 [inline]
    __kmalloc_cache_noprof+0x47a/0x710 mm/slub.c:5415
    kmalloc_noprof include/linux/slab.h:950 [inline]
    kzalloc_noprof include/linux/slab.h:1188 [inline]
    dev_iommu_get+0x10c/0x1a0 drivers/iommu/iommu.c:408
    iommu_fwspec_init+0x288/0x4d0 drivers/iommu/iommu.c:3087
    iommu_mock_device_add+0x46/0xb0 drivers/iommu/iommu.c:385
    mock_dev_create drivers/iommu/iommufd/selftest.c:1025 [inline]
    iommufd_test_mock_domain drivers/iommu/iommufd/selftest.c:1066 [inline]
    iommufd_test+0x2f8a/0x6190 drivers/iommu/iommufd/selftest.c:2072
    iommufd_fops_ioctl+0x367/0x540 drivers/iommu/iommufd/main.c:533
    vfs_ioctl fs/ioctl.c:51 [inline]
    __do_sys_ioctl fs/ioctl.c:597 [inline]
    __se_sys_ioctl fs/ioctl.c:583 [inline]
    __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0x116/0x800 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

Fix this by calling dev_iommu_free(dev) instead of iommu_fwspec_free(dev)
in the device_add() failure path. dev_iommu_free() frees both fwspec
and the outer dev_iommu struct and clears dev->iommu.

Reported-by: Peiyang He <peiyang_he@smail.nju.edu.cn>
Fixes: 2a918911ed3d ("iommufd: Register iommufd mock devices with fwspec")
Cc: stable@vger.kernel.org
Signed-off-by: Peiyang He <peiyang_he@smail.nju.edu.cn>
---
 drivers/iommu/iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index e8f13dcebbde..23a531595835 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -390,7 +390,7 @@ int iommu_mock_device_add(struct device *dev, struct iommu_device *iommu)
 
 	rc = device_add(dev);
 	if (rc)
-		iommu_fwspec_free(dev);
+		dev_iommu_free(dev);
 	return rc;
 }
 EXPORT_SYMBOL_GPL(iommu_mock_device_add);

base-commit: dc59e4fea9d83f03bad6bddf3fa2e52491777482
-- 
2.43.0

On Sat, Jul 11, 2026 at 01:51:19PM +0800, Peiyang He wrote:
> iommu_mock_device_add() first calls iommu_fwspec_init(), which on
> success allocates both dev->iommu (via dev_iommu_get()) and
> dev->iommu->fwspec. If the subsequent device_add(dev) call fails,
> the error path only calls iommu_fwspec_free(dev), which frees
> fwspec but leaves dev->iommu still allocated.
> 
> This triggers the following kmemleak report when fuzzing with Syzkaller:
> 
> Fix this by calling dev_iommu_free(dev) instead of iommu_fwspec_free(dev)
> in the device_add() failure path. dev_iommu_free() frees both fwspec
> and the outer dev_iommu struct and clears dev->iommu.
> 
> Reported-by: Peiyang He <peiyang_he@smail.nju.edu.cn>
> Fixes: 2a918911ed3d ("iommufd: Register iommufd mock devices with fwspec")
> Cc: stable@vger.kernel.org
> Signed-off-by: Peiyang He <peiyang_he@smail.nju.edu.cn>
> ---
>  drivers/iommu/iommu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Applied thanks

Jason