| 1 | From 28335a4704d8d615fd61e05ea6e435a4cd24e4df Mon Sep 17 00:00:00 2001 |
| 2 | From: Qualys Security Advisory <qsa@qualys.com> |
| 3 | Date: Sun, 21 Feb 2021 22:13:18 -0800 |
| 4 | Subject: [PATCH 18/29] Security: Fix off-by-one in smtp transport (read |
| 5 | response) |
| 6 | |
| 7 | Based on Heiko Schlittermann's commit 1887a160. This fixes: |
| 8 | |
| 9 | 1/ In src/transports/smtp.c: |
| 10 | |
| 11 | 2281 int n = sizeof(sx->buffer); |
| 12 | 2282 uschar * rsp = sx->buffer; |
| 13 | 2283 |
| 14 | 2284 if (sx->esmtp_sent && (n = Ustrlen(sx->buffer)) < sizeof(sx->buffer)/2) |
| 15 | 2285 { rsp = sx->buffer + n + 1; n = sizeof(sx->buffer) - n; } |
| 16 | |
| 17 | This should probably be either: |
| 18 | |
| 19 | rsp = sx->buffer + n + 1; n = sizeof(sx->buffer) - n - 1; |
| 20 | |
| 21 | or: |
| 22 | |
| 23 | rsp = sx->buffer + n; n = sizeof(sx->buffer) - n; |
| 24 | |
| 25 | (not sure which) to avoid an off-by-one. |
| 26 | --- |
| 27 | src/transports/smtp.c | 4 ++-- |
| 28 | 1 file changed, 2 insertions(+), 2 deletions(-) |
| 29 | |
| 30 | diff --git a/src/transports/smtp.c b/src/transports/smtp.c |
| 31 | index cc37e73f3..07b63a2aa 100644 |
| 32 | --- a/src/transports/smtp.c |
| 33 | +++ b/src/transports/smtp.c |
| 34 | @@ -2328,8 +2328,8 @@ goto SEND_QUIT; |
| 35 | int n = sizeof(sx->buffer); |
| 36 | uschar * rsp = sx->buffer; |
| 37 | |
| 38 | - if (sx->esmtp_sent && (n = Ustrlen(sx->buffer)) < sizeof(sx->buffer)/2) |
| 39 | - { rsp = sx->buffer + n + 1; n = sizeof(sx->buffer) - n; } |
| 40 | + if (sx->esmtp_sent && (n = Ustrlen(sx->buffer) + 1) < sizeof(sx->buffer)/2) |
| 41 | + { rsp = sx->buffer + n; n = sizeof(sx->buffer) - n; } |
| 42 | |
| 43 | if (smtp_write_command(sx, SCMD_FLUSH, "HELO %s\r\n", sx->helo_data) < 0) |
| 44 | goto SEND_FAILED; |
| 45 | -- |
| 46 | 2.30.2 |
| 47 | |