Fix CVE-2017-16944: https://bugs.exim.org/show_bug.cgi?id=2201 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-16944 Patch copied from upstream source repository: https://git.exim.org/exim.git/commit/4804c62909a62a3ac12ec4777ebd48c541028965 From 4804c62909a62a3ac12ec4777ebd48c541028965 Mon Sep 17 00:00:00 2001 From: "Heiko Schlittermann (HS12-RIPE)" Date: Mon, 27 Nov 2017 22:42:33 +0100 Subject: [PATCH] Chunking: do not treat the first lonely dot special. CVE-2017-16944, Bug 2201 (cherry picked from commit 178ecb70987f024f0e775d87c2f8b2cf587dd542) Change log update (cherry picked from commit b488395f4d99d44a950073a64b35ec8729102782) --- doc/doc-txt/ChangeLog | 6 +++++- src/src/receive.c | 2 +- src/src/smtp_in.c | 7 +++++++ 3 files changed, 13 insertions(+), 2 deletions(-) #diff --git a/doc/doc-txt/ChangeLog b/doc/doc-txt/ChangeLog #index a2d9339..541ebaf 100644 #--- a/doc/doc-txt/ChangeLog #+++ b/doc/doc-txt/ChangeLog #@@ -61,7 +61,11 @@ JH/30 Fix a logging bug on aarch64: an unsafe routine was previously used for # # JH/34 Bug 2199: fix a use-after-free while reading smtp input for header lines. # A crafted sequence of BDAT commands could result in in-use memory beeing #- freed. #+ freed. CVE-2017-16943. #+ #+HS/03 Bug 2201: Fix checking for leading-dot on a line during headers reading #+ from SMTP input. Previously it was always done; now only done for DATA #+ and not BDAT commands. CVE-2017-16944. # # # Exim version 4.89 diff --git a/src/src/receive.c b/src/src/receive.c index 20672db..2812ea2 100644 --- a/src/receive.c +++ b/src/receive.c @@ -1827,7 +1827,7 @@ for (;;) prevent further reading), and break out of the loop, having freed the empty header, and set next = NULL to indicate no data line. */ - if (ptr == 0 && ch == '.' && (smtp_input || dot_ends)) + if (ptr == 0 && ch == '.' && dot_ends) { ch = (receive_getc)(GETC_BUFFER_UNLIMITED); if (ch == '\r') diff --git a/src/src/smtp_in.c b/src/src/smtp_in.c index 1b45f84..0207540 100644 --- a/src/smtp_in.c +++ b/src/smtp_in.c @@ -4955,16 +4955,23 @@ while (done <= 0) DEBUG(D_receive) debug_printf("chunking state %d, %d bytes\n", (int)chunking_state, chunking_data_left); + /* push the current receive_* function on the "stack", and + replace them by bdat_getc(), which in turn will use the lwr_receive_* + functions to do the dirty work. */ lwr_receive_getc = receive_getc; lwr_receive_ungetc = receive_ungetc; + receive_getc = bdat_getc; receive_ungetc = bdat_ungetc; + dot_ends = FALSE; + goto DATA_BDAT; } case DATA_CMD: HAD(SCH_DATA); + dot_ends = TRUE; DATA_BDAT: /* Common code for DATA and BDAT */ if (!discarded && recipients_count <= 0) -- 1.9.1