From: Darrick J. Wong <darrick.wong@oracle.com>
Date: Thu, 12 Dec 2013 18:07:33 +0000 (-0500)
Subject: e4defrag: don't crash if umounts the filesystem races with us
X-Git-Tag: v1.42.9~75
X-Git-Url: http://git.ipfire.org/gitweb/gitweb.cgi?a=commitdiff_plain;h=e661d2815194d6db3f3e38223277569ad55bb420;p=thirdparty%2Fe2fsprogs.git

e4defrag: don't crash if umounts the filesystem races with us

If someone umounts the filesystem between statfs64() and the getmntent()
iteration, we can exit the loop having never set mnt_type, and strcmp
can crash.  Fix the potential NULL dereference.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---

diff --git a/misc/e4defrag.c b/misc/e4defrag.c
index 4b31d0362..b6e2e3195 100644
--- a/misc/e4defrag.c
+++ b/misc/e4defrag.c
@@ -374,7 +374,7 @@ static int is_ext4(const char *file, char *devname)
 	}
 
 	endmntent(fp);
-	if (strcmp(mnt_type, FS_EXT4) == 0) {
+	if (mnt_type && strcmp(mnt_type, FS_EXT4) == 0) {
 		FREE(mnt_type);
 		return 0;
 	} else {