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asymmetric_keys: reject trust keys without IDs

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The PKCS#8 parser deliberately leaves the asym_key_ids payload slot
empty. key_or_keyring_common() unconditionally dereferences that slot
when a PKCS#8 key is supplied to a key_or_keyring restriction. Both the
plain and :chain forms reach this branch, allowing an unprivileged caller
to trigger a NULL pointer dereference through KEYCTL_RESTRICT_KEYRING
followed by add_key().

 Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000
 KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
 RIP: 0010:key_or_keyring_common (crypto/asymmetric_keys/restrict.c:205 crypto/asymmetric_keys/restrict.c:279)
 Call Trace:
  <TASK>
  __key_create_or_update (security/keys/key.c:884)
  key_create_or_update (security/keys/key.c:1021)
  __do_sys_add_key (security/keys/keyctl.c:134)
  do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
  </TASK>
 Kernel panic - not syncing: Fatal exception

Reject an asymmetric restriction key without key IDs. A PKCS#8 private
key cannot identify the signer of a candidate certificate and is not a
valid trust anchor.

Fixes: 3c58b2362b ("KEYS: Implement PKCS#8 RSA Private Key parser [ver #2]")
Cc: stable@vger.kernel.org
Reported-by: Xiang Mei <xmei5@asu.edu>
Link: https://lore.kernel.org/r/20260429181629.110802-2-bestswngs@gmail.com
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Weiming Shi <bestswngs@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Weiming Shi 2026-09-06 19:01:53 +08:00 committed by Herbert Xu
parent f033e862a3
commit 9695df3b1d
1 changed files with 6 additions and 2 deletions
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8
crypto/asymmetric_keys/restrict.c
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@ -243,10 +243,14 @@ static int key_or_keyring_common(struct key *dest_keyring,
if (IS_ERR(key))
key = NULL;
} else if (trusted->type == &key_type_asymmetric) {
const struct asymmetric_key_ids *kids;
const struct asymmetric_key_id **signer_ids;
signer_ids = (const struct asymmetric_key_id **)
asymmetric_key_ids(trusted)->id;
kids = asymmetric_key_ids(trusted);
if (!kids)
return -ENOKEY;
signer_ids = (const struct asymmetric_key_id **)kids->id;
/*
* The auth_ids come from the candidate key (the