From: Theodore Ts'o <tytso@mit.edu>
Date: Wed, 1 Jul 2009 02:49:49 +0000 (-0400)
Subject: libuuid, uuidd: Avoid infinite loop while reading from the socket fd
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3b90c50066969cfa40a392d0290cb8d762351f65;p=util-linux

libuuid, uuidd: Avoid infinite loop while reading from the socket fd

If for some reason the uuidd daemon or the process calling uuidd
exited unexpectely, the read_all() function would end up looping
forever, either in uuidd or in libuuid.  Fix this terminating the loop
if no data can be read after five tries to read from the file
descriptor.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---

diff --git a/misc-utils/uuidd.c b/misc-utils/uuidd.c
index 42844571..74bab693 100644
--- a/misc-utils/uuidd.c
+++ b/misc-utils/uuidd.c
@@ -84,19 +84,23 @@ static void create_daemon(void)
 		die("setreuid");
 }
 
-static int read_all(int fd, char *buf, size_t count)
+static ssize_t read_all(int fd, char *buf, size_t count)
 {
 	ssize_t ret;
-	int c = 0;
+	ssize_t c = 0;
+	int tries = 0;
 
 	memset(buf, 0, count);
 	while (count > 0) {
 		ret = read(fd, buf, count);
-		if (ret < 0) {
-			if ((errno == EAGAIN) || (errno == EINTR))
+		if (ret <= 0) {
+			if ((errno == EAGAIN || errno == EINTR || ret == 0) &&
+			    (tries++ < 5))
 				continue;
-			return -1;
+			return c ? c : -1;
 		}
+		if (ret > 0)
+			tries = 0;
 		count -= ret;
 		buf += ret;
 		c += ret;
diff --git a/shlibs/uuid/src/gen_uuid.c b/shlibs/uuid/src/gen_uuid.c
index 32a6453b..13096c0d 100644
--- a/shlibs/uuid/src/gen_uuid.c
+++ b/shlibs/uuid/src/gen_uuid.c
@@ -425,15 +425,19 @@ static ssize_t read_all(int fd, char *buf, size_t count)
 {
 	ssize_t ret;
 	ssize_t c = 0;
+	int tries = 0;
 
 	memset(buf, 0, count);
 	while (count > 0) {
 		ret = read(fd, buf, count);
-		if (ret < 0) {
-			if ((errno == EAGAIN) || (errno == EINTR))
+		if (ret <= 0) {
+			if ((errno == EAGAIN || errno == EINTR || ret == 0) &&
+			    (tries++ < 5))
 				continue;
-			return -1;
+			return c ? c : -1;
 		}
+		if (ret > 0)
+			tries = 0;
 		count -= ret;
 		buf += ret;
 		c += ret;