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43 lines
1.2 KiB
43 lines
1.2 KiB
2 years ago
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From 4b7d9cd4a018898d7714ce06f3faf2626c14582b Mon Sep 17 00:00:00 2001
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From: Werner Koch <wk@gnupg.org>
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Date: Wed, 5 Oct 2022 14:19:06 +0200
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Subject: [PATCH] Detect a possible overflow directly in the TLV parser.
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* src/ber-help.c (_ksba_ber_read_tl): Check for overflow of a commonly
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used sum.
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--
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It is quite common to have checks like
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if (ti.nhdr + ti.length >= DIM(tmpbuf))
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return gpg_error (GPG_ERR_TOO_LARGE);
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This patch detects possible integer overflows immmediately when
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creating the TI object.
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Reported-by: ZDI-CAN-18927, ZDI-CAN-18928, ZDI-CAN-18929
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---
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src/ber-help.c | 6 ++++++
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1 file changed, 6 insertions(+)
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diff --git a/src/ber-help.c b/src/ber-help.c
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index 81c31ed..56efb6a 100644
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--- a/src/ber-help.c
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+++ b/src/ber-help.c
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@@ -182,6 +182,12 @@ _ksba_ber_read_tl (ksba_reader_t reader, struct tag_info *ti)
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ti->length = len;
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}
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+ if (ti->length > ti->nhdr && (ti->nhdr + ti->length) < ti->length)
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+ {
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+ ti->err_string = "header+length would overflow";
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+ return gpg_error (GPG_ERR_EOVERFLOW);
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+ }
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+
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/* Without this kludge some example certs can't be parsed */
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if (ti->class == CLASS_UNIVERSAL && !ti->tag)
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ti->length = 0;
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--
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2.37.3
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