[PATCH RFC v2 3/5] KEYS: trusted: Do not use WARN when encode fails

Jarkko Sakkinen
2024-05-19T00:26:50Z

When asn1_encode_sequence() fails, WARN is not the correct solution.

1. asn1_encode_sequence() is not an internal function (located
in lib/asn1_encode.c).
2. Location is known, which makes the stack trace useless.
3. Results a crash if panic_on_warn is set.

It is also noteworthy that the use of WARN is undocumented, and it
should be avoided unless there is a carefully considered rationale to
use it.

Replace WARN with pr_err, and print the return value instead, which is
only useful piece of information.

Cc: stable@vger.kernel.org # v5.13+
Fixes: f2219745250f ("security: keys: trusted: use ASN.1 TPM2 key format for the blobs")
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
security/keys/trusted-keys/trusted_tpm2.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index dfeec06301ce..dbdd6a318b8b 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -38,6 +38,7 @@ static int tpm2_key_encode(struct trusted_key_payload *payload,
u8 *end_work = scratch + SCRATCH_SIZE;
u8 *priv, *pub;
u16 priv_len, pub_len;
+ int ret;

priv_len = get_unaligned_be16(src) + 2;
priv = src;
@@ -79,8 +80,11 @@ static int tpm2_key_encode(struct trusted_key_payload *payload,
work1 = payload->blob;
work1 = asn1_encode_sequence(work1, work1 + sizeof(payload->blob),
scratch, work - scratch);
- if (WARN(IS_ERR(work1), "BUG: ASN.1 encoder failed"))
- return PTR_ERR(work1);
+ if (IS_ERR(work1)) {
+ ret = PTR_ERR(work1);
+ pr_err("ASN.1 encode error %d\n", ret);
+ return ret;
+ }

return work1 - payload->blob;
}
--
2.45.1