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iommufd/selftest: Fix buffer read overrrun in the dirty test

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test_bit() is used to read the memory storing the bitmap, however
test_bit() always uses a unsigned long 8 byte access.

If the bitmap is not an aligned size of 64 bits this will now trigger a
KASAN warning reading past the end of the buffer.

Properly round the buffer allocation to an unsigned long size. Continue to
copy_from_user() using a byte granularity.

Fixes: 9560393b83 ("iommufd/selftest: Fix iommufd_test_dirty() to handle <u8 bitmaps")
Link: https://patch.msgid.link/r/0-v1-113e8d9e7861+5ae-iommufd_kasan_jgg@nvidia.com
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Jason Gunthorpe
2024-08-27 09:47:04 -03:00
parent 1d4684fbe8
commit 79ea4a496a
1 changed files with 4 additions and 5 deletions
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drivers/iommu/iommufd/selftest.c
+4 -5
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@@ -1343,7 +1343,7 @@ static int iommufd_test_dirty(struct iommufd_ucmd *ucmd, unsigned int mockpt_id,
unsigned long page_size, void __user *uptr,
u32 flags)
{
unsigned long bitmap_size, i, max;
unsigned long i, max;
struct iommu_test_cmd *cmd = ucmd->cmd;
struct iommufd_hw_pagetable *hwpt;
struct mock_iommu_domain *mock;
@@ -1364,15 +1364,14 @@ static int iommufd_test_dirty(struct iommufd_ucmd *ucmd, unsigned int mockpt_id,
}
max = length / page_size;
bitmap_size = DIV_ROUND_UP(max, BITS_PER_BYTE);
tmp = kvzalloc(bitmap_size, GFP_KERNEL_ACCOUNT);
tmp = kvzalloc(DIV_ROUND_UP(max, BITS_PER_LONG) * sizeof(unsigned long),
GFP_KERNEL_ACCOUNT);
if (!tmp) {
rc = -ENOMEM;
goto out_put;
}
if (copy_from_user(tmp, uptr, bitmap_size)) {
if (copy_from_user(tmp, uptr,DIV_ROUND_UP(max, BITS_PER_BYTE))) {
rc = -EFAULT;
goto out_free;
}