6.11-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jason Gunthorpe <jgg@xxxxxxxxxx>
[ Upstream commit 79ea4a496ab5c970a3a793d863ed8893b1af107c ]
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: 9560393b830b ("iommufd/selftest: Fix iommufd_test_dirty() to handle <u8 bitmaps")
Link: https://patch.msgid.link/r/0-v1-113e8d9e7861+5ae-iommufd_kasan_jgg@xxxxxxxxxx
Reviewed-by: Joao Martins <joao.m.martins@xxxxxxxxxx>
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/iommu/iommufd/selftest.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/drivers/iommu/iommufd/selftest.c b/drivers/iommu/iommufd/selftest.c
index 222cfc11ebfd0..4a279b8f02cb7 100644
--- a/drivers/iommu/iommufd/selftest.c
+++ b/drivers/iommu/iommufd/selftest.c
@@ -1342,7 +1342,7 @@ 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;
@@ -1363,15 +1363,14 @@ 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;
}
--
2.43.0
