In gsi_trans_pool_init_dma(), the total size of a pool of memory
used for DMA transactions is calculated. However the calculation is
done incorrectly.
For 4KB pages, this total size is currently always more than one
page, and as a result, the calculation produces a positive (though
incorrect) total size. The code still works in this case; we just
end up with fewer DMA pool entries than we intended.
Bjorn Andersson tested booting a kernel with 16KB pages, and hit a
null pointer derereference in sg_alloc_append_table_from_pages(),
descending from gsi_trans_pool_init_dma(). The cause of this was
that a 16KB total size was going to be allocated, and with 16KB
pages the order of that allocation is 0. The total_size calculation
yielded 0, which eventually led to the crash.
Correcting the total_size calculation fixes the problem.
Reported-by: Bjorn Andersson <[email protected]>
Tested-by: Bjorn Andersson <[email protected]>
Fixes: 9dd441e4ed57 ("soc: qcom: ipa: GSI transactions")
Signed-off-by: Alex Elder <[email protected]>
---
Note: This was reported via private communication.
v2: - Added Bjorn's actual name to tags.
drivers/net/ipa/gsi_trans.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/ipa/gsi_trans.c b/drivers/net/ipa/gsi_trans.c
index 0f52c068c46d6..ee6fb00b71eb6 100644
--- a/drivers/net/ipa/gsi_trans.c
+++ b/drivers/net/ipa/gsi_trans.c
@@ -156,7 +156,7 @@ int gsi_trans_pool_init_dma(struct device *dev, struct gsi_trans_pool *pool,
* gsi_trans_pool_exit_dma() can assume the total allocated
* size is exactly (count * size).
*/
- total_size = get_order(total_size) << PAGE_SHIFT;
+ total_size = PAGE_SIZE << get_order(total_size);
virt = dma_alloc_coherent(dev, total_size, &addr, GFP_KERNEL);
if (!virt)
--
2.34.1
On Tue, Mar 28, 2023 at 11:08:33AM -0500, Alex Elder wrote:
> In gsi_trans_pool_init_dma(), the total size of a pool of memory
> used for DMA transactions is calculated. However the calculation is
> done incorrectly.
>
> For 4KB pages, this total size is currently always more than one
> page, and as a result, the calculation produces a positive (though
> incorrect) total size. The code still works in this case; we just
> end up with fewer DMA pool entries than we intended.
>
> Bjorn Andersson tested booting a kernel with 16KB pages, and hit a
> null pointer derereference in sg_alloc_append_table_from_pages(),
> descending from gsi_trans_pool_init_dma(). The cause of this was
> that a 16KB total size was going to be allocated, and with 16KB
> pages the order of that allocation is 0. The total_size calculation
> yielded 0, which eventually led to the crash.
>
> Correcting the total_size calculation fixes the problem.
>
> Reported-by: Bjorn Andersson <[email protected]>
> Tested-by: Bjorn Andersson <[email protected]>
> Fixes: 9dd441e4ed57 ("soc: qcom: ipa: GSI transactions")
> Signed-off-by: Alex Elder <[email protected]>
> ---
> Note: This was reported via private communication.
> v2: - Added Bjorn's actual name to tags.
You discarded Mark's Reviewed-by tag.
>
> drivers/net/ipa/gsi_trans.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
Thanks,
Reviewed-by: Leon Romanovsky <[email protected]>