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dma-direct: check return value when encrypting or decrypting memory 

__change_page_attr() can fail which will cause set_memory_encrypted() and
set_memory_decrypted() to return non-zero.

If the device requires unencrypted DMA memory and decryption fails, simply
free the memory and fail.

If attempting to re-encrypt in the failure path and that encryption fails,
there is no alternative other than to leak the memory.

Fixes: c10f07aa27 ("dma/direct: Handle force decryption for DMA coherent buffers in common code")
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
David Rientjes 2020-06-11 12:20:30 -07:00 committed by Christoph Hellwig
parent 96a539fa3b
commit 56fccf21d1
1 changed files with 14 additions and 5 deletions
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19
kernel/dma/direct.c
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@ -158,6 +158,7 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
{ {
struct page *page; struct page *page;
void *ret; void *ret;
int err;
size = PAGE_ALIGN(size); size = PAGE_ALIGN(size);
@ -210,8 +211,12 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
} }
ret = page_address(page); ret = page_address(page);
if (force_dma_unencrypted(dev)) if (force_dma_unencrypted(dev)) {
set_memory_decrypted((unsigned long)ret, 1 << get_order(size)); err = set_memory_decrypted((unsigned long)ret,
1 << get_order(size));
if (err)
goto out_free_pages;
}
memset(ret, 0, size); memset(ret, 0, size);
@ -230,9 +235,13 @@ done:
return ret; return ret;
out_encrypt_pages: out_encrypt_pages:
if (force_dma_unencrypted(dev)) if (force_dma_unencrypted(dev)) {
set_memory_encrypted((unsigned long)page_address(page), err = set_memory_encrypted((unsigned long)page_address(page),
1 << get_order(size)); 1 << get_order(size));
/* If memory cannot be re-encrypted, it must be leaked */
if (err)
return NULL;
}
out_free_pages: out_free_pages:
dma_free_contiguous(dev, page, size); dma_free_contiguous(dev, page, size);
return NULL; return NULL;