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> [OP: backport to 5.4: adjusted context] Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
060f38b1df
commit
b2f140a9f9
@ -156,13 +156,3 @@ accesses to DMA buffers in both privileged "supervisor" and unprivileged
|
|||||||
subsystem that the buffer is fully accessible at the elevated privilege
|
subsystem that the buffer is fully accessible at the elevated privilege
|
||||||
level (and ideally inaccessible or at least read-only at the
|
level (and ideally inaccessible or at least read-only at the
|
||||||
lesser-privileged levels).
|
lesser-privileged levels).
|
||||||
|
|
||||||
DMA_ATTR_PRIVILEGED
|
|
||||||
-------------------
|
|
||||||
|
|
||||||
Some advanced peripherals such as remote processors and GPUs perform
|
|
||||||
accesses to DMA buffers in both privileged "supervisor" and unprivileged
|
|
||||||
"user" modes. This attribute is used to indicate to the DMA-mapping
|
|
||||||
subsystem that the buffer is fully accessible at the elevated privilege
|
|
||||||
level (and ideally inaccessible or at least read-only at the
|
|
||||||
lesser-privileged levels).
|
|
||||||
|
@ -70,14 +70,6 @@
|
|||||||
*/
|
*/
|
||||||
#define DMA_ATTR_PRIVILEGED (1UL << 9)
|
#define DMA_ATTR_PRIVILEGED (1UL << 9)
|
||||||
|
|
||||||
/*
|
|
||||||
* This is a hint to the DMA-mapping subsystem that the device is expected
|
|
||||||
* to overwrite the entire mapped size, thus the caller does not require any
|
|
||||||
* of the previous buffer contents to be preserved. This allows
|
|
||||||
* bounce-buffering implementations to optimise DMA_FROM_DEVICE transfers.
|
|
||||||
*/
|
|
||||||
#define DMA_ATTR_OVERWRITE (1UL << 10)
|
|
||||||
|
|
||||||
/*
|
/*
|
||||||
* A dma_addr_t can hold any valid DMA or bus address for the platform.
|
* A dma_addr_t can hold any valid DMA or bus address for the platform.
|
||||||
* It can be given to a device to use as a DMA source or target. A CPU cannot
|
* It can be given to a device to use as a DMA source or target. A CPU cannot
|
||||||
|
@ -571,11 +571,14 @@ found:
|
|||||||
*/
|
*/
|
||||||
for (i = 0; i < nslots; i++)
|
for (i = 0; i < nslots; i++)
|
||||||
io_tlb_orig_addr[index+i] = orig_addr + (i << IO_TLB_SHIFT);
|
io_tlb_orig_addr[index+i] = orig_addr + (i << IO_TLB_SHIFT);
|
||||||
if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
|
/*
|
||||||
(!(attrs & DMA_ATTR_OVERWRITE) || dir == DMA_TO_DEVICE ||
|
* When dir == DMA_FROM_DEVICE we could omit the copy from the orig
|
||||||
dir == DMA_BIDIRECTIONAL))
|
* to the tlb buffer, if we knew for sure the device will
|
||||||
swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_TO_DEVICE);
|
* 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(orig_addr, tlb_addr, mapping_size, DMA_TO_DEVICE);
|
||||||
return tlb_addr;
|
return tlb_addr;
|
||||||
}
|
}
|
||||||
|
|
||||||
|
Loading…
Reference in New Issue
Block a user