[PATCH 5.15 21/23] KEYS: trusted: Do not use WARN when encode fails

Greg Kroah-Hartman
2024-05-23T13:19:05Z

5.15-stable review patch. If anyone has any objections, please let me know.

------------------

From: Jarkko Sakkinen <jarkko@kernel.org>

commit 050bf3c793a07f96bd1e2fd62e1447f731ed733b upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
security/keys/trusted-keys/trusted_tpm2.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -84,8 +84,9 @@ static int tpm2_key_encode(struct truste
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")) {
+ if (IS_ERR(work1)) {
ret = PTR_ERR(work1);
+ pr_err("BUG: ASN.1 encoder failed with %d\n", ret);
goto err;
}