The "config.offset" comes from the user.  There needs to a check to
prevent it being out of bounds.  The "config.offset" and
"dev->config_size" variables are both type u32.  So if the offset if
out of bounds then the "dev->config_size - config.offset" subtraction
results in a very high u32 value.

Fixes: c8a6153b6c59 ("vduse: Introduce VDUSE - vDPA Device in Userspace")
Signed-off-by: Dan Carpenter <[email protected]>
---
 drivers/vdpa/vdpa_user/vduse_dev.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c 
b/drivers/vdpa/vdpa_user/vduse_dev.c
index c9204c62f339..2f789dca0c0b 100644
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -975,7 +975,8 @@ static long vduse_dev_ioctl(struct file *file, unsigned int 
cmd,
                        break;
 
                ret = -EINVAL;
-               if (config.length == 0 ||
+               if (config.offset < dev->config_size ||
+                   config.length == 0 ||
                    config.length > dev->config_size - config.offset)
                        break;
 
-- 
2.20.1

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