Messages in this thread Patch in this message |  | | From | Tycho Andersen <> | | Subject | [PATCH v1 3/4] crypto/ccp: Check for page allocation failure correctly in TIO | | Date | Wed, 8 Apr 2026 08:32:58 -0600 |
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From: "Tycho Andersen (AMD)" <tycho@kernel.org>
Sashiko notes:
> if __snp_alloc_firmware_pages() returns NULL under memory pressure, is it > safe to pass it directly to page_address()? > > On architectures without HASHED_PAGE_VIRTUAL, page_address(NULL) might > compute a deterministic but invalid, non-zero virtual address. The > subsequent if (tio_status) check would then evaluate to true, and > sev_tsm_init_locked() would dereference the invalid pointer.
Indeed, page_address(NULL) will return non-NULL garbage here. Fix this by checking the page allocation itself for NULL, not the resulting virtual address.
Fixes: 4be423572da1 ("crypto/ccp: Implement SEV-TIO PCIe IDE (phase1)") Reported-by: Sashiko Assisted-by: Gemini:gemini-3.1-pro-preview Link: https://sashiko.dev/#/patchset/20260324161301.1353976-1-tycho%40kernel.org Signed-off-by: Tycho Andersen (AMD) <tycho@kernel.org> --- drivers/crypto/ccp/sev-dev.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c index e87efcff8df2..11e2c667c0ad 100644 --- a/drivers/crypto/ccp/sev-dev.c +++ b/drivers/crypto/ccp/sev-dev.c @@ -1488,6 +1488,8 @@ static int __sev_snp_init_locked(int *error, unsigned int max_snp_asid) &snp_panic_notifier); if (data.tio_en) { + struct page *page; + /* * This executes with the sev_cmd_mutex held so down the stack * snp_reclaim_pages(locked=false) might be needed (which is extremely @@ -1495,12 +1497,14 @@ static int __sev_snp_init_locked(int *error, unsigned int max_snp_asid) * Instead of exporting __snp_alloc_firmware_pages(), allocate a page * for this one call here. */ - void *tio_status = page_address(__snp_alloc_firmware_pages( - GFP_KERNEL_ACCOUNT | __GFP_ZERO, 0, true)); + page = __snp_alloc_firmware_pages(GFP_KERNEL_ACCOUNT | __GFP_ZERO, + 0, true); + if (page) { + void *tio_status = page_address(page); - if (tio_status) { sev_tsm_init_locked(sev, tio_status); - __snp_free_firmware_pages(virt_to_page(tio_status), 0, true); + + __snp_free_firmware_pages(page, 0, true); } } -- 2.53.0
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