From 88ee2872695aa22780b4e07e75e4b860d364594c Mon Sep 17 00:00:00 2001 From: Joseph Sutton Date: Mon, 10 Oct 2022 20:33:09 +1300 Subject: [PATCH] gsskrb5: CVE-2022-3437 Check for overflow in _gsskrb5_get_mech() If len_len is equal to total_len - 1 (i.e. the input consists only of a 0x60 byte and a length), the expression 'total_len - 1 - len_len - 1', used as the 'len' parameter to der_get_length(), will overflow to SIZE_MAX. Then der_get_length() will proceed to read, unconstrained, whatever data follows in memory. Add a check to ensure that doesn't happen. Samba BUG: https://bugzilla.samba.org/show_bug.cgi?id=15134 Signed-off-by: Joseph Sutton Reviewed-by: Andrew Bartlett --- lib/gssapi/krb5/decapsulate.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/lib/gssapi/krb5/decapsulate.c b/lib/gssapi/krb5/decapsulate.c index 031a621eabc7..d7b75a642224 100644 --- a/lib/gssapi/krb5/decapsulate.c +++ b/lib/gssapi/krb5/decapsulate.c @@ -54,6 +54,8 @@ _gsskrb5_get_mech (const u_char *ptr, e = der_get_length (p, total_len - 1, &len, &len_len); if (e || 1 + len_len + len != total_len) return -1; + if (total_len < 1 + len_len + 1) + return -1; p += len_len; if (*p++ != 0x06) return -1; -- 2.38.1