Messages in this thread | | | Date | Mon, 22 Oct 2018 11:06:09 +0300 | From | Mika Westerberg <> | Subject | Re: [PATCH] thunderbolt: fix a missing-check bug |
| |
On Sat, Oct 20, 2018 at 03:15:56PM -0500, Wenwen Wang wrote: > In tb_ring_poll(), the flag of the frame, i.e., > 'ring->descriptors[ring->tail].flags', is checked to see whether the frame > is completed. If yes, the frame including the flag will be read from the > ring and returned to the caller. The problem here is that the flag is > actually in a DMA region, which is allocated through dma_alloc_coherent() > in tb_ring_alloc(). Given that the device can also access this DMA region, > it is possible that a malicious device controlled by an attacker can modify > the flag between the check and the copy. By doing so, the attacker can > bypass the check and supply uncompleted frame, which can cause undefined > behavior of the kernel and introduce potential security risk. > > This patch firstly copies the flag into a local variable 'desc_flags' and > then performs the check and copy using 'desc_flags'. Through this way, the > above issue can be avoided.
Same here :)
| |