With vmalloc stack addresses enabled (CONFIG_VMAP_STACK=y) DCP trusted
keys can crash during en- and decryption of the blob encryption key via
the DCP crypto driver. This is caused by improperly using sg_init_one()
with vmalloc'd stack buffers (plain_key_blob).
Fix this by always using kmalloc() for buffers we give to the DCP crypto
driver.
Cc: stable@xxxxxxxxxxxxxxx # v6.10+
Fixes: 0e28bf61a5f9 ("KEYS: trusted: dcp: fix leak of blob encryption key")
Signed-off-by: David Gstir <david@xxxxxxxxxxxxx>
---
security/keys/trusted-keys/trusted_dcp.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)
diff --git a/security/keys/trusted-keys/trusted_dcp.c b/security/keys/trusted-keys/trusted_dcp.c
index e908c53a803c..7b6eb655df0c 100644
--- a/security/keys/trusted-keys/trusted_dcp.c
+++ b/security/keys/trusted-keys/trusted_dcp.c
@@ -201,12 +201,16 @@ static int trusted_dcp_seal(struct trusted_key_payload *p, char *datablob)
{
struct dcp_blob_fmt *b = (struct dcp_blob_fmt *)p->blob;
int blen, ret;
- u8 plain_blob_key[AES_KEYSIZE_128];
+ u8 *plain_blob_key;
blen = calc_blob_len(p->key_len);
if (blen > MAX_BLOB_SIZE)
return -E2BIG;
+ plain_blob_key = kmalloc(AES_KEYSIZE_128, GFP_KERNEL);
+ if (!plain_blob_key)
+ return -ENOMEM;
+
b->fmt_version = DCP_BLOB_VERSION;
get_random_bytes(b->nonce, AES_KEYSIZE_128);
get_random_bytes(plain_blob_key, AES_KEYSIZE_128);
@@ -229,7 +233,8 @@ static int trusted_dcp_seal(struct trusted_key_payload *p, char *datablob)
ret = 0;
out:
- memzero_explicit(plain_blob_key, sizeof(plain_blob_key));
+ memzero_explicit(plain_blob_key, AES_KEYSIZE_128);
+ kfree(plain_blob_key);
return ret;
}
@@ -238,7 +243,7 @@ static int trusted_dcp_unseal(struct trusted_key_payload *p, char *datablob)
{
struct dcp_blob_fmt *b = (struct dcp_blob_fmt *)p->blob;
int blen, ret;
- u8 plain_blob_key[AES_KEYSIZE_128];
+ u8 *plain_blob_key = NULL;
if (b->fmt_version != DCP_BLOB_VERSION) {
pr_err("DCP blob has bad version: %i, expected %i\n",
@@ -256,6 +261,12 @@ static int trusted_dcp_unseal(struct trusted_key_payload *p, char *datablob)
goto out;
}
+ plain_blob_key = kmalloc(AES_KEYSIZE_128, GFP_KERNEL);
+ if (!plain_blob_key) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
ret = decrypt_blob_key(b->blob_key, plain_blob_key);
if (ret) {
pr_err("Unable to decrypt blob key: %i\n", ret);
@@ -271,7 +282,10 @@ static int trusted_dcp_unseal(struct trusted_key_payload *p, char *datablob)
ret = 0;
out:
- memzero_explicit(plain_blob_key, sizeof(plain_blob_key));
+ if (plain_blob_key) {
+ memzero_explicit(plain_blob_key, AES_KEYSIZE_128);
+ kfree(plain_blob_key);
+ }
return ret;
}
--
2.47.0
