36 lines
1.1 KiB
Diff
36 lines
1.1 KiB
Diff
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 1/3] 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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Index: libksba-1.3.5/src/ber-help.c
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===================================================================
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--- libksba-1.3.5.orig/src/ber-help.c
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+++ libksba-1.3.5/src/ber-help.c
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@@ -181,6 +181,12 @@ _ksba_ber_read_tl (ksba_reader_t reader,
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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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