From: Jean-Philippe Brucker <jphilippe.brucker@gmail.com>
Date: Sat, 3 Mar 2018 16:59:44 +0000 (+0000)
Subject: ss: fix NULL dereference when rendering without header
X-Git-Tag: v5.0.0~245^2~5
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=eb8559eff124221bfbafe934c4dbfe30f20604c0;p=mirror_iproute2.git

ss: fix NULL dereference when rendering without header

When ss is invoked with the no-header flag, if the query doesn't return
any result, render() is called with 'buffer' uninitialized. This
currently leads to a segfault. Ensure that buffer is initialized before
rendering.

The bug can be triggered with: ss -H sport = 100000

Signed-off-by: Jean-Philippe Brucker <jphilippe.brucker@gmail.com>
Acked-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---

diff --git a/misc/ss.c b/misc/ss.c
index e047f9c0..e087bef7 100644
--- a/misc/ss.c
+++ b/misc/ss.c
@@ -1197,10 +1197,15 @@ newline:
 /* Render buffered output with spacing and delimiters, then free up buffers */
 static void render(int screen_width)
 {
-	struct buf_token *token = (struct buf_token *)buffer.head->data;
+	struct buf_token *token;
 	int printed, line_started = 0;
 	struct column *f;
 
+	if (!buffer.head)
+		return;
+
+	token = (struct buf_token *)buffer.head->data;
+
 	/* Ensure end alignment of last token, it wasn't necessarily flushed */
 	buffer.tail->end += buffer.cur->len % 2;