Am 08.10.21 um 08:29 schrieb guangming.cao@xxxxxxxxxxxx:
From: Guangming Cao <Guangming.Cao@xxxxxxxxxxxx>
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@xxxxxxxxxxxx>
---
drivers/dma-buf/dma-buf.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 511fe0d217a0..aebb51b3ff52 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -80,7 +80,9 @@ static void dma_buf_release(struct dentry *dentry)
dma_resv_fini(dmabuf->resv);
module_put(dmabuf->owner);
+ spin_lock(&dmabuf->name_lock);
kfree(dmabuf->name);
+ spin_unlock(&dmabuf->name_lock);
That here is certainly a NAK. This is the release function if somebody
is changing the name on a released DMA-buf we have much bigger problems.
kfree(dmabuf);
}
@@ -1372,6 +1374,8 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
if (ret)
goto error_unlock;
+
+ spin_lock(&dmabuf->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 +1383,7 @@ 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(&dmabuf->name_lock);
Yeah, that part looks like a good idea to me as well.
Christian.
robj = buf_obj->resv;
fence = dma_resv_excl_fence(robj);
