openssh/openssh-8.7p1-CVE-2023-25136.patch
Dmitry Belyavskiy f7003be68c Resolve possible self-DoS with some clients
Resolves: rhbz#2186473
2023-04-13 14:24:35 +02:00

39 lines
1.2 KiB
Diff

diff --git a/compat.c b/compat.c
index 46dfe3a9c2e..478a9403eea 100644
--- a/compat.c
+++ b/compat.c
@@ -190,26 +190,26 @@ compat_pkalg_proposal(struct ssh *ssh, char *pkalg_prop)
char *
compat_kex_proposal(struct ssh *ssh, char *p)
{
- char *cp = NULL;
+ char *cp = NULL, *cp2 = NULL;
if ((ssh->compat & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0)
return xstrdup(p);
debug2_f("original KEX proposal: %s", p);
if ((ssh->compat & SSH_BUG_CURVE25519PAD) != 0)
- if ((p = match_filter_denylist(p,
+ if ((cp = match_filter_denylist(p,
"curve25519-sha256@libssh.org")) == NULL)
fatal("match_filter_denylist failed");
if ((ssh->compat & SSH_OLD_DHGEX) != 0) {
- cp = p;
- if ((p = match_filter_denylist(p,
+ if ((cp2 = match_filter_denylist(cp ? cp : p,
"diffie-hellman-group-exchange-sha256,"
"diffie-hellman-group-exchange-sha1")) == NULL)
fatal("match_filter_denylist failed");
free(cp);
+ cp = cp2;
}
- debug2_f("compat KEX proposal: %s", p);
- if (*p == '\0')
+ if (cp == NULL || *cp == '\0')
fatal("No supported key exchange algorithms found");
- return p;
+ debug2_f("compat KEX proposal: %s", cp);
+ return cp;
}