tpm2_load_cmd() does boundary checks against the ASN.1 size i.e., payload->blob_len. Address this by passing the decoded blob size to tpm2_load_cmd(), and use it for the boundary checks.
Cc: [email protected] # v5.13+ Fixes: f2219745250f ("security: keys: trusted: use ASN.1 TPM2 key format for the blobs") Reported-by: [email protected] Closes: https://bugs.sh/b/6a581c4284f721d4/ Signed-off-by: Jarkko Sakkinen <[email protected]> --- security/keys/trusted-keys/trusted_tpm2.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c index 67225dd562a9..01f18bb37047 100644 --- a/security/keys/trusted-keys/trusted_tpm2.c +++ b/security/keys/trusted-keys/trusted_tpm2.c @@ -99,7 +99,7 @@ struct tpm2_key_context { static int tpm2_key_decode(struct trusted_key_payload *payload, struct trusted_key_options *options, - u8 **buf) + u8 **buf, unsigned int *blob_len) { int ret; struct tpm2_key_context ctx; @@ -120,6 +120,7 @@ static int tpm2_key_decode(struct trusted_key_payload *payload, return -ENOMEM; *buf = blob; + *blob_len = ctx.priv_len + ctx.pub_len; options->keyhandle = ctx.parent; memcpy(blob, ctx.priv, ctx.priv_len); @@ -384,10 +385,11 @@ static int tpm2_load_cmd(struct tpm_chip *chip, int rc; u32 attrs; - rc = tpm2_key_decode(payload, options, &blob); + rc = tpm2_key_decode(payload, options, &blob, &blob_len); if (rc) { /* old form */ blob = payload->blob; + blob_len = payload->blob_len; payload->old_format = 1; } else { /* Bind for cleanup: */ @@ -399,17 +401,17 @@ static int tpm2_load_cmd(struct tpm_chip *chip, return -EINVAL; /* must be big enough for at least the two be16 size counts */ - if (payload->blob_len < 4) + if (blob_len < 4) return -EINVAL; private_len = get_unaligned_be16(blob); /* must be big enough for following public_len */ - if (private_len + 2 + 2 > (payload->blob_len)) + if (private_len + 2 + 2 > blob_len) return -E2BIG; public_len = get_unaligned_be16(blob + 2 + private_len); - if (private_len + 2 + public_len + 2 > payload->blob_len) + if (private_len + 2 + public_len + 2 > blob_len) return -E2BIG; pub = blob + 2 + private_len + 2; -- 2.47.3
