![Peter Korsgaard](/assets/img/avatar_default.png)
Fixes the following security issue: CVE-2018-6789: Meh Chang discovered a buffer overflow flaw in a utility function used in the SMTP listener of Exim, a mail transport agent. A remote attacker can take advantage of this flaw to cause a denial of service, or potentially the execution of arbitrary code via a specially crafted message. Dropped ChangeLog hunk and adjusted file path of upstream commit so it applies to tarball. Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
38 lines
1,016 B
Diff
38 lines
1,016 B
Diff
From 062990cc1b2f9e5d82a413b53c8f0569075de700 Mon Sep 17 00:00:00 2001
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From: "Heiko Schlittermann (HS12-RIPE)" <hs@schlittermann.de>
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Date: Mon, 5 Feb 2018 22:23:32 +0100
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Subject: [PATCH] Fix base64d() buffer size (CVE-2018-6789)
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Credits for discovering this bug: Meh Chang <meh@devco.re>
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[Peter: Drop ChangeLog change, fix path]
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Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
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---
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src/base64.c | 8 ++++++--
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1 file changed, 6 insertions(+), 2 deletions(-)
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diff --git a/src/base64.c b/src/base64.c
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index f6f187f0..e58ca6c7 100644
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--- a/src/base64.c
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+++ b/src/base64.c
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@@ -152,10 +152,14 @@ static uschar dec64table[] = {
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int
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b64decode(const uschar *code, uschar **ptr)
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{
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+
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int x, y;
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-uschar *result = store_get(3*(Ustrlen(code)/4) + 1);
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+uschar *result;
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-*ptr = result;
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+{
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+ int l = Ustrlen(code);
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+ *ptr = result = store_get(1 + l/4 * 3 + l%4);
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+}
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/* Each cycle of the loop handles a quantum of 4 input bytes. For the last
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quantum this may decode to 1, 2, or 3 output bytes. */
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--
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2.11.0
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