From: Alex Elder elder@linaro.org
[ Upstream commit 6c75dc94f2b27fff57b305af9236eea181a00b6c ]
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 quic_bjorande@quicinc.com Tested-by: Bjorn Andersson quic_bjorande@quicinc.com Fixes: 9dd441e4ed57 ("soc: qcom: ipa: GSI transactions") Reviewed-by: Mark Bloch mbloch@nvidia.com Signed-off-by: Alex Elder elder@linaro.org Reviewed-by: Leon Romanovsky leonro@nvidia.com Link: https://lore.kernel.org/r/20230328162751.2861791-1-elder@linaro.org Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 70c2b585f98d6..1e0d626393012 100644 --- a/drivers/net/ipa/gsi_trans.c +++ b/drivers/net/ipa/gsi_trans.c @@ -159,7 +159,7 @@ 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)