openssh/SOURCES/openssh-9.1p1-sshbanner.patch

33 lines
1003 B
Diff

diff --git a/ssh-keyscan.c b/ssh-keyscan.c
index d29a03b4..d7283136 100644
--- a/ssh-keyscan.c
+++ b/ssh-keyscan.c
@@ -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);