From: Karel Zak <kzak@redhat.com>
Date: Wed, 19 Jun 2024 09:19:49 +0000 (+0200)
Subject: libmount: improving robustness in reading kernel messages
X-Git-Tag: v2.40.2~25
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1e37fb6e4b71367f9fd4b719a1ab23ad88cbc593;p=thirdparty%2Futil-linux.git

libmount: improving robustness in reading kernel messages

* Ensure data termination from read() function
* Allocate space for terminator using "sizeof(buf)-1"

Signed-off-by: Karel Zak <kzak@redhat.com>
(cherry picked from commit 0389a9eae9281405d177d0eb9ad979d7bd47a7c6)
---

diff --git a/libmount/src/hook_mount.c b/libmount/src/hook_mount.c
index 10b226636..af84f755e 100644
--- a/libmount/src/hook_mount.c
+++ b/libmount/src/hook_mount.c
@@ -73,9 +73,15 @@ static void save_fd_messages(struct libmnt_context *cxt, int fd)
 	free(cxt->syscall_errmsg);
 	cxt->syscall_errmsg = NULL;
 
-	while ((rc = read(fd, buf, sizeof(buf))) != -1) {
-		if (rc > 0 && buf[rc - 1] == '\n')
-			buf[rc - 1] = '\0';
+	while ((rc = read(fd, buf, sizeof(buf) - 1)) != -1) {
+
+		if (rc == 0)
+			continue;
+		if (buf[rc - 1] == '\n')
+			buf[--rc] = '\0';
+		else
+			buf[rc] = '\0';
+
 		DBG(CXT, ul_debug("message from kernel: \"%*s\"", rc, buf));
 
 		if (rc < 3 || strncmp((char *) buf, "e ", 2) != 0)