From dc1db0060c02d119fd4196924eff2d1129e9a442 Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Wed, 8 Dec 2021 18:09:56 +0300 Subject: [PATCH] vduse: check that offset is within bounds in get_config() This condition checks "len" but it does not check "offset" and that could result in an out of bounds read if "offset > dev->config_size". The problem is that since both variables are unsigned the "dev->config_size - offset" subtraction would result in a very high unsigned value. I think these checks might not be necessary because "len" and "offset" are supposed to already have been validated using the vhost_vdpa_config_validate() function. But I do not know the code perfectly, and I like to be safe. Fixes: c8a6153b6c59 ("vduse: Introduce VDUSE - vDPA Device in Userspace") Signed-off-by: Dan Carpenter Link: https://lore.kernel.org/r/20211208150956.GA29160@kili Signed-off-by: Michael S. Tsirkin Cc: stable@vger.kernel.org --- 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 1a206f95d73a..eddcb64a910a 100644 --- a/drivers/vdpa/vdpa_user/vduse_dev.c +++ b/drivers/vdpa/vdpa_user/vduse_dev.c @@ -655,7 +655,8 @@ static void vduse_vdpa_get_config(struct vdpa_device *vdpa, unsigned int offset, { struct vduse_dev *dev = vdpa_to_vduse(vdpa); - if (len > dev->config_size - offset) + if (offset > dev->config_size || + len > dev->config_size - offset) return; memcpy(buf, dev->config + offset, len);