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Message-Id: <20230328162751.2861791-1-elder@linaro.org>
Date: Tue, 28 Mar 2023 11:27:51 -0500
From: Alex Elder <elder@...aro.org>
To: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
pabeni@...hat.com
Cc: quic_bjorande@...cinc.com, mbloch@...dia.com,
caleb.connolly@...aro.org, mka@...omium.org, evgreen@...omium.org,
andersson@...nel.org, quic_cpratapa@...cinc.com,
quic_avuyyuru@...cinc.com, quic_jponduru@...cinc.com,
quic_subashab@...cinc.com, elder@...nel.org,
netdev@...r.kernel.org, linux-arm-msm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH net v3] net: ipa: compute DMA pool size properly
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@...cinc.com>
Tested-by: Bjorn Andersson <quic_bjorande@...cinc.com>
Fixes: 9dd441e4ed57 ("soc: qcom: ipa: GSI transactions")
Reviewed-by: Mark Bloch <mbloch@...dia.com>
Signed-off-by: Alex Elder <elder@...aro.org>
---
Note: This was reported via private communication.
v3: - Added Mark Bloch's reviewed-by tag.
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
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