From 91dfd98216d817ec5f1c55890bacb7b4fe9b068a Mon Sep 17 00:00:00 2001
From: David Rientjes <rientjes@google.com>
Date: Fri, 30 Dec 2022 14:18:46 -0800
Subject: [PATCH] crypto: ccp - Avoid page allocation failure warning for SEV_GET_ID2
Git-commit: 91dfd98216d817ec5f1c55890bacb7b4fe9b068a
Patch-mainline: v6.3-rc1
References: git-fixes
For SEV_GET_ID2, the user provided length does not have a specified
limitation because the length of the ID may change in the future. The
kernel memory allocation, however, is implicitly limited to 4MB on x86 by
the page allocator, otherwise the kzalloc() will fail.
When this happens, it is best not to spam the kernel log with the warning.
Simply fail the allocation and return ENOMEM to the user.
Fixes: d6112ea0cb34 ("crypto: ccp - introduce SEV_GET_ID2 command")
Reported-by: Andy Nguyen <theflow@google.com>
Reported-by: Peter Gonda <pgonda@google.com>
Suggested-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/crypto/ccp/sev-dev.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 06fc7156c04f..56998bc579d6 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -881,7 +881,14 @@ static int sev_ioctl_do_get_id2(struct sev_issue_cmd *argp)
input_address = (void __user *)input.address;
if (input.address && input.length) {
- id_blob = kzalloc(input.length, GFP_KERNEL);
+ /*
+ * The length of the ID shouldn't be assumed by software since
+ * it may change in the future. The allocation size is limited
+ * to 1 << (PAGE_SHIFT + MAX_ORDER - 1) by the page allocator.
+ * If the allocation fails, simply return ENOMEM rather than
+ * warning in the kernel log.
+ */
+ id_blob = kzalloc(input.length, GFP_KERNEL | __GFP_NOWARN);
if (!id_blob)
return -ENOMEM;
--
2.35.3