From: Nikola Forró <nforro@redhat.com>
Date: Thu, 16 Jan 2020 17:43:50 +0000 (+0100)
Subject: api.c: Fix potential buffer overflow
X-Git-Tag: v0.42.1~1^2~4
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=76b745519e77f83d207a2e0ddc332e812797543b;p=thirdparty%2Flibcgroup.git

api.c: Fix potential buffer overflow

It is assumed that arguments read from /proc/<pid>/cmdline don't exceed
buf_pname buffer size, which is FILENAME_MAX - 1 characters, but that's
not always the case.

Add check to prevent buffer overflow and discard the excessive part of
an argument.

Signed-off-by: Nikola Forró <nforro@redhat.com>
Reviewed-by: Tom Hromatka <tom.hromatka@oracle.com>
---

diff --git a/src/api.c b/src/api.c
index 92730e6a..959a8140 100644
--- a/src/api.c
+++ b/src/api.c
@@ -4601,13 +4601,17 @@ static int cg_get_procname_from_proc_cmdline(pid_t pid,
 
 	while (c != EOF) {
 		c = fgetc(f);
-		if ((c != EOF) && (c != '\0')) {
+		if ((c != EOF) && (c != '\0') && (len < FILENAME_MAX - 1)) {
 			buf_pname[len] = c;
 			len++;
 			continue;
 		}
 		buf_pname[len] = '\0';
 
+		if (len == FILENAME_MAX - 1)
+			while ((c != EOF) && (c != '\0'))
+				c = fgetc(f);
+
 		/*
 		 * The taken process name from /proc/<pid>/status is
 		 * shortened to 15 characters if it is over. So the