74 lines
2.5 KiB
Diff
74 lines
2.5 KiB
Diff
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Fix CVE-2018-6003:
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https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-6003
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https://lists.gnu.org/archive/html/help-libtasn1/2018-01/msg00000.html
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Patch copied from upstream source repository:
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https://gitlab.com/gnutls/libtasn1/commit/c593ae84cfcde8fea45787e53950e0ac71e9ca97
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From c593ae84cfcde8fea45787e53950e0ac71e9ca97 Mon Sep 17 00:00:00 2001
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From: Nikos Mavrogiannopoulos <nmav@redhat.com>
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Date: Thu, 4 Jan 2018 10:52:05 +0100
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Subject: [PATCH] _asn1_decode_simple_ber: restrict the levels of recursion to 3
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On indefinite string decoding, setting a maximum level of recursions
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protects the BER decoder from a stack exhaustion due to large amounts
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of recursion.
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Signed-off-by: Nikos Mavrogiannopoulos <nmav@redhat.com>
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---
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lib/decoding.c | 21 +++++++++++++++++++--
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1 file changed, 19 insertions(+), 2 deletions(-)
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diff --git a/lib/decoding.c b/lib/decoding.c
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index 2240b09..0ee35d3 100644
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--- a/lib/decoding.c
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+++ b/lib/decoding.c
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@@ -45,6 +45,13 @@
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#define DECODE_FLAG_HAVE_TAG 1
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#define DECODE_FLAG_INDEFINITE (1<<1)
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+/* On indefinite string decoding, allow this maximum levels
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+ * of recursion. Allowing infinite recursion, makes the BER
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+ * decoder susceptible to stack exhaustion due to that recursion.
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+ */
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+#define DECODE_FLAG_LEVEL1 (1<<2)
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+#define DECODE_FLAG_LEVEL2 (1<<3)
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+#define DECODE_FLAG_LEVEL3 (1<<4)
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#define DECR_LEN(l, s) do { \
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l -= s; \
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@@ -2216,7 +2223,8 @@ _asn1_decode_simple_ber (unsigned int etype, const unsigned char *der,
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}
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/* indefinite constructed */
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- if (((dflags & DECODE_FLAG_INDEFINITE) || class == ASN1_CLASS_STRUCTURED) && ETYPE_IS_STRING(etype))
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+ if ((((dflags & DECODE_FLAG_INDEFINITE) || class == ASN1_CLASS_STRUCTURED) && ETYPE_IS_STRING(etype)) &&
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+ !(dflags & DECODE_FLAG_LEVEL3))
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{
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len_len = 1;
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@@ -2236,8 +2244,17 @@ _asn1_decode_simple_ber (unsigned int etype, const unsigned char *der,
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do
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{
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unsigned tmp_len;
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+ unsigned flags = DECODE_FLAG_HAVE_TAG;
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+
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+ if (dflags & DECODE_FLAG_LEVEL1)
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+ flags |= DECODE_FLAG_LEVEL2;
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+ else if (dflags & DECODE_FLAG_LEVEL2)
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+ flags |= DECODE_FLAG_LEVEL3;
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+ else
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+ flags |= DECODE_FLAG_LEVEL1;
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- result = asn1_decode_simple_ber(etype, p, der_len, &out, &out_len, &tmp_len);
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+ result = _asn1_decode_simple_ber(etype, p, der_len, &out, &out_len, &tmp_len,
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+ flags);
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if (result != ASN1_SUCCESS)
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{
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warn();
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--
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libgit2 0.26.0
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