redis/redis-CVE-2021-32675.patch

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From 71be97294abf3657710a044157ebbc8a21489da3 Mon Sep 17 00:00:00 2001
From: Oran Agra <oran@redislabs.com>
Date: Wed, 9 Jun 2021 17:31:39 +0300
Subject: [PATCH] Prevent unauthenticated client from easily consuming lots of
memory (CVE-2021-32675)
This change sets a low limit for multibulk and bulk length in the
protocol for unauthenticated connections, so that they can't easily
cause redis to allocate massive amounts of memory by sending just a few
characters on the network.
The new limits are 10 arguments of 16kb each (instead of 1m of 512mb)
(cherry picked from commit 3d221e81f3b680543e34942579af190b049ff283)
---
src/networking.c | 8 ++++++++
tests/unit/auth.tcl | 16 ++++++++++++++++
2 files changed, 24 insertions(+)
diff --git a/src/networking.c b/src/networking.c
index bfaded9b4d0..2b8588094d2 100644
--- a/src/networking.c
+++ b/src/networking.c
@@ -1309,6 +1309,10 @@ int processMultibulkBuffer(client *c) {
addReplyError(c,"Protocol error: invalid multibulk length");
setProtocolError("invalid mbulk count",c);
return C_ERR;
+ } else if (ll > 10 && server.requirepass && !c->authenticated) {
+ addReplyError(c, "Protocol error: unauthenticated multibulk length");
+ setProtocolError("unauth mbulk count", c);
+ return C_ERR;
}
c->qb_pos = (newline-c->querybuf)+2;
@@ -1354,6 +1358,10 @@ int processMultibulkBuffer(client *c) {
addReplyError(c,"Protocol error: invalid bulk length");
setProtocolError("invalid bulk length",c);
return C_ERR;
+ } else if (ll > 16384 && server.requirepass && !c->authenticated) {
+ addReplyError(c, "Protocol error: unauthenticated bulk length");
+ setProtocolError("unauth bulk length", c);
+ return C_ERR;
}
c->qb_pos = newline-c->querybuf+2;
diff --git a/tests/unit/auth.tcl b/tests/unit/auth.tcl
index 633cda95c92..f5da728e845 100644
--- a/tests/unit/auth.tcl
+++ b/tests/unit/auth.tcl
@@ -24,4 +24,20 @@ start_server {tags {"auth"} overrides {requirepass foobar}} {
r set foo 100
r incr foo
} {101}
+
+ test {For unauthenticated clients multibulk and bulk length are limited} {
+ set rr [redis [srv "host"] [srv "port"] 0]
+ $rr write "*100\r\n"
+ $rr flush
+ catch {[$rr read]} e
+ assert_match {*unauthenticated multibulk length*} $e
+ $rr close
+
+ set rr [redis [srv "host"] [srv "port"] 0]
+ $rr write "*1\r\n\$100000000\r\n"
+ $rr flush
+ catch {[$rr read]} e
+ assert_match {*unauthenticated bulk length*} $e
+ $rr close
+ }
}