Commit d5244993 authored May 31, 2024 by Rick Edgecombe Committed by Jinjiang Tu May 31, 2024

dma-direct: Leak pages on dma_set_decrypted() failure

mainline inclusion
from mainline-v6.9-rc1
commit b9fa16949d18e06bdf728a560f5c8af56d2bdcaf
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9QGIS
CVE: CVE-2024-35939

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b9fa16949d18e06bdf728a560f5c8af56d2bdcaf



--------------------------------

On TDX it is possible for the untrusted host to cause
set_memory_encrypted() or set_memory_decrypted() to fail such that an
error is returned and the resulting memory is shared. Callers need to
take care to handle these errors to avoid returning decrypted (shared)
memory to the page allocator, which could lead to functional or security
issues.

DMA could free decrypted/shared pages if dma_set_decrypted() fails. This
should be a rare case. Just leak the pages in this case instead of
freeing them.

Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

Conflicts:
	kernel/dma/direct.c
[Context conflicts.]
Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>

parent 3b9084bc

kernel/dma/direct.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -243,7 +243,7 @@ void dma_direct_alloc(struct device dev, size_t size,
		err = set_memory_decrypted((unsigned long)ret,
		PFN_UP(size));
		if (err)
		goto out_free_pages;
		goto out_leak_pages;
		}

		memset(ret, 0, size);
		@@ -270,6 +270,8 @@ void dma_direct_alloc(struct device dev, size_t size,
		out_free_pages:
		__dma_direct_free_pages(dev, page, size);
		return NULL;
		out_leak_pages:
		return NULL;
		}

		void dma_direct_free(struct device *dev, size_t size,
		@@ -333,7 +335,7 @@ struct page dma_direct_alloc_pages(struct device dev, size_t size,
		ret = page_address(page);
		if (force_dma_unencrypted(dev)) {
		if (set_memory_decrypted((unsigned long)ret, PFN_UP(size)))
		goto out_free_pages;
		goto out_leak_pages;
		}
		memset(ret, 0, size);
		*dma_handle = phys_to_dma_direct(dev, page_to_phys(page));
		@@ -341,6 +343,8 @@ struct page dma_direct_alloc_pages(struct device dev, size_t size,
		out_free_pages:
		__dma_direct_free_pages(dev, page, size);
		return NULL;
		out_leak_pages:
		return NULL;
		}

		void dma_direct_free_pages(struct device *dev, size_t size,