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| author | Ed Maste <emaste@FreeBSD.org> | 2022-10-04 20:28:13 +0000 |
|---|---|---|
| committer | Ed Maste <emaste@FreeBSD.org> | 2022-10-07 01:39:00 +0000 |
| commit | 1057339079a0cb37648fa2afe44e9eceec737439 (patch) | |
| tree | ef5f6459fe6c32d20143de858b2ce2f9ee906850 | |
| parent | dd75360fe538f3ff8919bfd1eb20dca94093ebe4 (diff) | |
| download | src-1057339079a0cb37648fa2afe44e9eceec737439.tar.gz src-1057339079a0cb37648fa2afe44e9eceec737439.zip | |
ssh-keyscan: Strictly enforce the maximum allowed SSH2 banner size
From OpenSSH-portable commit ff89b1bed807, OpenBSD commit 6ae664f9f4db.
MFC after: 3 days
(cherry picked from commit 5e5ebbee81bfd1c034caffa00d58d4e06e1b26ee)
| -rw-r--r-- | crypto/openssh/ssh-keyscan.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/crypto/openssh/ssh-keyscan.c b/crypto/openssh/ssh-keyscan.c index d29a03b4e68a..d7283136c7d2 100644 --- a/crypto/openssh/ssh-keyscan.c +++ b/crypto/openssh/ssh-keyscan.c @@ -1,4 +1,4 @@ -/* $OpenBSD: ssh-keyscan.c,v 1.145 2022/01/21 00:53:40 deraadt Exp $ */ +/* $OpenBSD: ssh-keyscan.c,v 1.146 2022/08/19 04:02:46 dtucker Exp $ */ /* * Copyright 1995, 1996 by David Mazieres <dm@lcs.mit.edu>. * @@ -490,6 +490,15 @@ congreet(int s) return; } + /* + * Read the server banner as per RFC4253 section 4.2. The "SSH-" + * protocol identification string may be preceeded by an arbitarily + * large banner which we must read and ignore. Loop while reading + * newline-terminated lines until we have one starting with "SSH-". + * The ID string cannot be longer than 255 characters although the + * preceeding banner lines may (in which case they'll be discarded + * in multiple iterations of the outer loop). + */ for (;;) { memset(buf, '\0', sizeof(buf)); bufsiz = sizeof(buf); @@ -517,6 +526,11 @@ congreet(int s) conrecycle(s); return; } + if (cp >= buf + sizeof(buf)) { + error("%s: greeting exceeds allowable length", c->c_name); + confree(s); + return; + } if (*cp != '\n' && *cp != '\r') { error("%s: bad greeting", c->c_name); confree(s); |