diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2022-03-28 21:37:05 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-04-08 15:24:13 +0300 |
| commit | 7007c894631cf43041dcfa0da7142bbaa7eb673c (patch) | |
| tree | 441b49b84f38eaf493046f765576ab4deeb3e323 /kernel | |
| parent | 63351e2e13625435843f901c8aa14751e09b6f45 (diff) | |
| download | linux-7007c894631cf43041dcfa0da7142bbaa7eb673c.tar.xz | |
Reinstate some of "swiotlb: rework "fix info leak with DMA_FROM_DEVICE""
commit 901c7280ca0d5e2b4a8929fbe0bfb007ac2a6544 upstream.
Halil Pasic points out [1] that the full revert of that commit (revert
in bddac7c1e02b), and that a partial revert that only reverts the
problematic case, but still keeps some of the cleanups is probably
better. 
And that partial revert [2] had already been verified by Oleksandr
Natalenko to also fix the issue, I had just missed that in the long
discussion.
So let's reinstate the cleanups from commit aa6f8dcbab47 ("swiotlb:
rework "fix info leak with DMA_FROM_DEVICE""), and effectively only
revert the part that caused problems.
Link: https://lore.kernel.org/all/20220328013731.017ae3e3.pasic@linux.ibm.com/ [1]
Link: https://lore.kernel.org/all/20220324055732.GB12078@lst.de/ [2]
Link: https://lore.kernel.org/all/4386660.LvFx2qVVIh@natalenko.name/ [3]
Suggested-by: Halil Pasic <pasic@linux.ibm.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/dma/swiotlb.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index aca0690550e2..912397dbc2a8 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -578,10 +578,14 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr, for (i = 0; i < nr_slots(alloc_size + offset); i++) mem->slots[index + i].orig_addr = slot_addr(orig_addr, i); tlb_addr = slot_addr(mem->start, index) + offset; - if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) && - (!(attrs & DMA_ATTR_OVERWRITE) || dir == DMA_TO_DEVICE || - dir == DMA_BIDIRECTIONAL)) - swiotlb_bounce(dev, tlb_addr, mapping_size, DMA_TO_DEVICE); + /* + * When dir == DMA_FROM_DEVICE we could omit the copy from the orig + * to the tlb buffer, if we knew for sure the device will + * overwirte the entire current content. But we don't. Thus + * unconditional bounce may prevent leaking swiotlb content (i.e. + * kernel memory) to user-space. + */ + swiotlb_bounce(dev, tlb_addr, mapping_size, DMA_TO_DEVICE); return tlb_addr; } |