From 4cfadd994e5ab6e57cc43164d1e3198bb4faedbb Mon Sep 17 00:00:00 2001 From: Qualys Security Advisory Date: Sun, 21 Feb 2021 19:11:55 -0800 Subject: [PATCH 03/29] CVE-2020-28023: Out-of-bounds read in smtp_setup_msg() Extracted from Jeremy Harris's commit afaf5a50. --- src/acl.c | 3 ++- src/macros.h | 1 + src/smtp_in.c | 4 ++-- 3 files changed, 5 insertions(+), 3 deletions(-) diff --git a/src/acl.c b/src/acl.c index f3b860e4a..49f6fe79c 100644 --- a/src/acl.c +++ b/src/acl.c @@ -4464,7 +4464,8 @@ switch (where) /* Drop cutthrough conns, and drop heldopen verify conns if the previous was not DATA */ { - uschar prev = smtp_connection_had[smtp_ch_index-2]; + uschar prev = + smtp_connection_had[SMTP_HBUFF_PREV(SMTP_HBUFF_PREV(smtp_ch_index))]; BOOL dropverify = !(prev == SCH_DATA || prev == SCH_BDAT); cancel_cutthrough_connection(dropverify, US"quit or conndrop"); diff --git a/src/macros.h b/src/macros.h index 0f93543ce..b3896b736 100644 --- a/src/macros.h +++ b/src/macros.h @@ -154,6 +154,7 @@ enough to hold all the headers from a normal kind of message. */ /* The size of the circular buffer that remembers recent SMTP commands */ #define SMTP_HBUFF_SIZE 20 +#define SMTP_HBUFF_PREV(n) ((n) ? (n)-1 : SMTP_HBUFF_SIZE-1) /* The initial size of a big buffer for use in various places. It gets put into big_buffer_size and in some circumstances increased. It should be at least diff --git a/src/smtp_in.c b/src/smtp_in.c index 86f87eae1..4265d77b7 100644 --- a/src/smtp_in.c +++ b/src/smtp_in.c @@ -5322,10 +5322,10 @@ while (done <= 0) } if (f.smtp_in_pipelining_advertised && last_was_rcpt) smtp_printf("503 Valid RCPT command must precede %s\r\n", FALSE, - smtp_names[smtp_connection_had[smtp_ch_index-1]]); + smtp_names[smtp_connection_had[SMTP_HBUFF_PREV(smtp_ch_index)]]); else done = synprot_error(L_smtp_protocol_error, 503, NULL, - smtp_connection_had[smtp_ch_index-1] == SCH_DATA + smtp_connection_had[SMTP_HBUFF_PREV(smtp_ch_index)] == SCH_DATA ? US"valid RCPT command must precede DATA" : US"valid RCPT command must precede BDAT"); -- 2.30.2