From: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
To: Vinod Koul <vinod.koul@intel.com>,
Maxime Coquelin <mcoquelin.stm32@gmail.com>,
Alexandre Torgue <alexandre.torgue@st.com>,
Dan Williams <dan.j.williams@intel.com>,
"M'boumba Cedric Madianga" <cedric.madianga@gmail.com>,
<dmaengine@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>
Cc: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
Subject: [PATCH v1 1/1] dmaengine: stm32-dmamux: fix a potential buffer overflow
Date: Tue, 13 Mar 2018 17:55:35 +0100 [thread overview]
Message-ID: <1520960135-26575-1-git-send-email-pierre-yves.mordret@st.com> (raw)
The bitfield dma_inuse is allocated of size dma_requests bits, thus a
valid bit address is from 0 to (dma_requests - 1).
When find_first_zero_bit() fails, it returns dma_requests as invalid
address.
Using such address for the following set_bit() is incorrect and, if
dma_requests is a multiple of BITS_PER_LONG, it will cause a buffer
overflow.
Currently this driver is only used in DT stm32h743.dtsi where a safe value
dma_requests=16 is not triggering the buffer overflow.
Fixed by checking the return value of find_first_zero_bit() _before_
using it.
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
---
Version history:
v1:
* Initial
---
---
drivers/dma/stm32-dmamux.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/dma/stm32-dmamux.c b/drivers/dma/stm32-dmamux.c
index 4dbb30c..b922db9 100644
--- a/drivers/dma/stm32-dmamux.c
+++ b/drivers/dma/stm32-dmamux.c
@@ -118,14 +118,15 @@ static void *stm32_dmamux_route_allocate(struct of_phandle_args *dma_spec,
spin_lock_irqsave(&dmamux->lock, flags);
mux->chan_id = find_first_zero_bit(dmamux->dma_inuse,
dmamux->dma_requests);
- set_bit(mux->chan_id, dmamux->dma_inuse);
- spin_unlock_irqrestore(&dmamux->lock, flags);
if (mux->chan_id == dmamux->dma_requests) {
+ spin_unlock_irqrestore(&dmamux->lock, flags);
dev_err(&pdev->dev, "Run out of free DMA requests\n");
ret = -ENOMEM;
- goto error;
+ goto error_chan_id;
}
+ set_bit(mux->chan_id, dmamux->dma_inuse);
+ spin_unlock_irqrestore(&dmamux->lock, flags);
/* Look for DMA Master */
for (i = 1, min = 0, max = dmamux->dma_reqs[i];
@@ -173,6 +174,8 @@ static void *stm32_dmamux_route_allocate(struct of_phandle_args *dma_spec,
error:
clear_bit(mux->chan_id, dmamux->dma_inuse);
+
+error_chan_id:
kfree(mux);
return ERR_PTR(ret);
}
--
2.7.4
next reply other threads:[~2018-03-13 16:55 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-13 16:55 Pierre-Yves MORDRET [this message]
2018-03-22 5:21 ` [PATCH v1 1/1] dmaengine: stm32-dmamux: fix a potential buffer overflow Vinod Koul
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1520960135-26575-1-git-send-email-pierre-yves.mordret@st.com \
--to=pierre-yves.mordret@st.com \
--cc=alexandre.torgue@st.com \
--cc=cedric.madianga@gmail.com \
--cc=dan.j.williams@intel.com \
--cc=dmaengine@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mcoquelin.stm32@gmail.com \
--cc=vinod.koul@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).