Commit a2d2e6ea authored Sep 09, 2025 by Janne Grunau Committed by Joerg Roedel Sep 13, 2025

iommu/io-pgtable-dart: Fix off by one error in table index check



The check for the dart table index allowed values of
(1 << data->tbl_bits) while only as many entries are initialized in
apple_dart_alloc_pgtable. This results in an array out of bounds access
when data->tbl_bits is at its maximal value of 2. When data->tbl_bits is
0 or 1 an unset (initialized to zero) data->pgd[] entry is used. In both
cases the value is used as pointer to read page table entries and
results in dereferencing invalid pointers.
There is no prior check that the passed iova is inside the iommu's IAS
so invalid values can be passed from driver's calling iommu_map().

Fixes: 74a0e72f ("iommu/io-pgtable-dart: Add 4-level page table support")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/asahi/aMACFlJjrZHs_Yf-@stanley.mountain/


Signed-off-by: Janne Grunau <j@jannau.net>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

parent ecf65089

drivers/iommu/io-pgtable-dart.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -177,7 +177,7 @@ static dart_iopte dart_get_last(struct dart_io_pgtable data, unsigned long iov
		int level = data->levels;
		int tbl = dart_get_index(data, iova, level);

		if (tbl > (1 << data->tbl_bits))
		if (tbl >= (1 << data->tbl_bits))
		return NULL;

		ptep = data->pgd[tbl];
		@@ -246,7 +246,7 @@ static int dart_map_pages(struct io_pgtable_ops *ops, unsigned long iova,

		tbl = dart_get_index(data, iova, level);

		if (tbl > (1 << data->tbl_bits))
		if (tbl >= (1 << data->tbl_bits))
		return -ENOMEM;

		ptep = data->pgd[tbl];