Commit ba75ecb9 authored by Tuo Li's avatar Tuo Li Committed by Greg Kroah-Hartman
Browse files

misc: bcm_vk: Fix possible null-pointer dereferences in bcm_vk_read() 



In the function bcm_vk_read(), the pointer entry is checked, indicating
that it can be NULL. If entry is NULL and rc is set to -EMSGSIZE, the
following code may cause null-pointer dereferences:

  struct vk_msg_blk tmp_msg = entry->to_h_msg[0];
  set_msg_id(&tmp_msg, entry->usr_msg_id);
  tmp_msg.size = entry->to_h_blks - 1;

To prevent these possible null-pointer dereferences, copy to_h_msg,
usr_msg_id, and to_h_blks from iter into temporary variables, and return
these temporary variables to the application instead of accessing them
through a potentially NULL entry.

Signed-off-by: default avatarTuo Li <islituo@gmail.com>
Reviewed-by: default avatarScott Branden <scott.branden@broadcom.com>
Link: https://patch.msgid.link/20251211063637.3987937-1-islituo@gmail.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent b54c82d6

drivers/misc/bcm-vk/bcm_vk_msg.c

+8 −4
Original line number Diff line number Diff line
@@ -1010,6 +1010,9 @@ ssize_t bcm_vk_read(struct file *p_file, 
	struct device *dev = &vk->pdev->dev;

	struct bcm_vk_msg_chan *chan = &vk->to_h_msg_chan;

	struct bcm_vk_wkent *entry = NULL, *iter;

	struct vk_msg_blk tmp_msg;

	u32 tmp_usr_msg_id;

	u32 tmp_blks;

	u32 q_num;

	u32 rsp_length;
@@ -1034,6 +1037,9 @@ ssize_t bcm_vk_read(struct file *p_file, 
					entry = iter;

				} else {

					/* buffer not big enough */

					tmp_msg = iter->to_h_msg[0];

					tmp_usr_msg_id = iter->usr_msg_id;

					tmp_blks = iter->to_h_blks;

					rc = -EMSGSIZE;

				}

				goto read_loop_exit;
@@ -1052,14 +1058,12 @@ ssize_t bcm_vk_read(struct file *p_file, 


		bcm_vk_free_wkent(dev, entry);

	} else if (rc == -EMSGSIZE) {

		struct vk_msg_blk tmp_msg = entry->to_h_msg[0];



		/*

		 * in this case, return just the first block, so

		 * that app knows what size it is looking for.

		 */

		set_msg_id(&tmp_msg, entry->usr_msg_id);

		tmp_msg.size = entry->to_h_blks - 1;

		set_msg_id(&tmp_msg, tmp_usr_msg_id);

		tmp_msg.size = tmp_blks - 1;

		if (copy_to_user(buf, &tmp_msg, VK_MSGQ_BLK_SIZE) != 0) {

			dev_err(dev, "Error return 1st block in -EMSGSIZE\n");

			rc = -EFAULT;