lkml.org 
[lkml]   [2020]   [Jun]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[patch for-5.8 3/4] 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: c10f07aa27da ("dma/direct: Handle force decryption for DMA coherent
buffers in common code")
Cc: stable@vger.kernel.org # 4.17+
Signed-off-by: David Rientjes <rientjes@google.com>
---
kernel/dma/direct.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -158,6 +158,7 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
{
struct page *page;
void *ret;
+ int err;

size = PAGE_ALIGN(size);

@@ -210,8 +211,12 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
}

ret = page_address(page);
- if (force_dma_unencrypted(dev))
- set_memory_decrypted((unsigned long)ret, 1 << get_order(size));
+ if (force_dma_unencrypted(dev)) {
+ err = set_memory_decrypted((unsigned long)ret,
+ 1 << get_order(size));
+ if (err)
+ goto out_free_pages;
+ }

memset(ret, 0, size);

@@ -229,9 +234,13 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
*dma_handle = phys_to_dma(dev, page_to_phys(page));
return ret;
out_encrypt_pages:
- if (force_dma_unencrypted(dev))
- set_memory_encrypted((unsigned long)page_address(page),
- 1 << get_order(size));
+ if (force_dma_unencrypted(dev)) {
+ err = set_memory_encrypted((unsigned long)page_address(page),
+ 1 << get_order(size));
+ /* If memory cannot be re-encrypted, it must be leaked */
+ if (err)
+ return NULL;
+ }
out_free_pages:
dma_free_contiguous(dev, page, size);
return NULL;
\
 
 \ /
  Last update: 2020-06-11 21:21    [W:0.130 / U:0.452 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site