linux-kernel - [PATCH v2] dma-buf: acquire name lock before read/write dma

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Date:   Fri, 8 Oct 2021 15:54:20 +0800
From:   <guangming.cao@...iatek.com>
To:     <christian.koenig@....com>
CC:     <dri-devel@...ts.freedesktop.org>, <guangming.cao@...iatek.com>,
        <linaro-mm-sig@...ts.linaro.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-media@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>, <matthias.bgg@...il.com>,
        <sumit.semwal@...aro.org>, <wsd_upstream@...iatek.com>,
        Guangming Cao <Guangming.Cao@...iatek.com>
Subject: [PATCH v2] dma-buf: acquire name lock before read/write dma_buf.name

From: Guangming Cao <Guangming.Cao@...iatek.com>

Because dma-buf.name can be freed in func: "dma_buf_set_name",
so, we need to acquire lock first before we read/write dma_buf.name
to prevent Use After Free(UAF) issue.

Signed-off-by: Guangming Cao <Guangming.Cao@...iatek.com>
---
 drivers/dma-buf/dma-buf.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 511fe0d217a0..a7f6fd13a635 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -1372,6 +1372,8 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
 		if (ret)
 			goto error_unlock;
 
+
+		spin_lock(&buf_obj->name_lock);
 		seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\t%s\n",
 				buf_obj->size,
 				buf_obj->file->f_flags, buf_obj->file->f_mode,
@@ -1379,6 +1381,7 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
 				buf_obj->exp_name,
 				file_inode(buf_obj->file)->i_ino,
 				buf_obj->name ?: "");
+		spin_unlock(&buf_obj->name_lock);
 
 		robj = buf_obj->resv;
 		fence = dma_resv_excl_fence(robj);
-- 
2.17.1