From 2618f76b277cef3df8ebdff403b05705f5f8a36d Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?J=C3=A9r=C3=A9my=20Jean?= Date: Fri, 21 Aug 2026 19:25:03 +0000 Subject: crypto: asymmetric_keys/x509 - copy X.509 TBS for data signature algorithms MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit For signature algorithms operating on a message rather than a digest, x509_get_sig_params() points sig->m directly into cert->tbs. cert->tbs is the preparsed add_key() payload. The syscall wipes and frees it on return, while the instantiated key retains public_key_signature. A later KEYCTL_LINK into an asymmetric restricted keyring therefore passes a dangling message pointer to ML-DSA. KASAN reports a slab-use-after-free in mldsa_verify(), with allocation and free provenance both leading to __do_sys_add_key(). Reuse is also an integrity issue: bytes occupying the freed object become the authenticated message instead of the certificate's own TBSCertificate. Give the signature object its own copy of the TBS, as is already done for a precomputed digest, and release it through the existing m_free contract. Fixes: f3eccecd782d ("pkcs7: Allow the signing algo to do whatever digestion it wants itself") Signed-off-by: Jérémy Jean Assisted-by: Codex:gpt-5 Signed-off-by: Herbert Xu --- crypto/asymmetric_keys/x509_public_key.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'crypto') diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c index 25cf8ac7f257..5c9165a83f91 100644 --- a/crypto/asymmetric_keys/x509_public_key.c +++ b/crypto/asymmetric_keys/x509_public_key.c @@ -53,9 +53,11 @@ int x509_get_sig_params(struct x509_certificate *cert) if (sig->algo_takes_data) { /* The signature algorithm does whatever passes for hashing. */ - sig->m = (u8 *)cert->tbs; + sig->m = kmemdup(cert->tbs, cert->tbs_size, GFP_KERNEL); + if (!sig->m) + return -ENOMEM; sig->m_size = cert->tbs_size; - sig->m_free = false; + sig->m_free = true; goto out; } -- cgit v1.2.3