[BUG] net: chelsio: Possible buffer overflow caused by DMA failures/attacks

[Jia-Ju Bai]

In alloc_rx_resources():
  sge->respQ.entries =
ÂÂÂ ÂÂÂ pci_alloc_consistent(pdev, size, &sge->respQ.dma_addr);

Thus, "sge->respQ.entries" is a DMA value, and it is assigned to
"e" in process_pure_responses():
ÂÂÂ struct sge *sge = adapter->sge;
ÂÂÂ struct respQ *q = &sge->respQ;
ÂÂÂ struct respQ_e *e = &q->entries[q->cidx];

When DMA failures or attacks occur, the data stored in "e" can be
changed at any time. In this case, the value of "e->FreelistQid"
can be a large number to cause buffer overflow when the
following code is executed:
ÂÂÂ const struct freelQ *fl = &sge->freelQ[e->FreelistQid];

Similarly, "sge->respQ.entries" is also assigned to "e" in
process_responses():
ÂÂÂ struct sge *sge = adapter->sge;
ÂÂÂ struct respQ *q = &sge->respQ;
ÂÂÂ struct respQ_e *e = &q->entries[q->cidx];

When DMA failures or attacks occur, the data stored in "e" can be
changed at any time. In this case, the value of "e->FreelistQid"
can be a large number to cause buffer overflow when the
following code is executed:
ÂÂÂ struct freelQ *fl = &sge->freelQ[e->FreelistQid];

Considering that DMA can fail or be attacked, I think that it is 
dangerous to
use a DMA value (or any value tainted by it) as an array index or a 
control-flow
condition. However, I have found many such dangerous cases in Linux 
device drivers
through my static-analysis tool and code review.
I am not sure whether my opinion is correct, so I want to listen to your 
points of view.
Thanks in advance :)


Best wishes,
Jia-Ju Bai