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@vger.kernel.org # v6.10+ Fixes: 0e28bf61a5f9 ("KEYS: trusted: dcp: fix leak of blob encryption key") Signed-off-by: David Gstir david@sigma-star.at --- 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; }