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X.509: Fix validation of ASN.1 certificate header

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x509_load_certificate_list() seeks to enforce that a certificate starts
with 0x30 0x82 (ASN.1 SEQUENCE tag followed by a length of more than 256
and less than 65535 bytes).

But it only enforces that *either* of those two byte values are present,
instead of checking for the *conjunction* of the two values.  Fix it.

Fixes: 631cc66eb9 ("MODSIGN: Provide module signing public keys to the kernel")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://lore.kernel.org/r/20260508033917.B5873C2BCB0@smtp.kernel.org/
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: stable@vger.kernel.org # v3.7+
Reviewed-by: Ignat Korchagin <ignat@linux.win>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Lukas Wunner 2026-05-14 08:55:58 +02:00 committed by Herbert Xu
parent 86ad806936
commit 3b626ba431
1 changed files with 1 additions and 1 deletions
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2
crypto/asymmetric_keys/x509_loader.c
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@ -20,7 +20,7 @@ int x509_load_certificate_list(const u8 cert_list[],
*/
if (end - p < 4)
goto dodgy_cert;
if (p[0] != 0x30 &&
if (p[0] != 0x30 ||
p[1] != 0x82)
goto dodgy_cert;
plen = (p[2] << 8) | p[3];