File util-linux-libmount-btrfs-crash.patch of Package util-linux.2662

From e9cd2e2bd9ec91a0b1050c4aa79555d142985924 Mon Sep 17 00:00:00 2001
From: Karel Zak <kzak@redhat.com>
Date: Thu, 31 Mar 2016 11:45:55 +0200
Subject: [PATCH] libmount: Fix possible NULL dereference in
 get_btrfs_fs_root()

The function mnt_table_get_fs_root() should be robust enough to accept
NULL as mountinfo -- the right behaviour is to default to '/'.

The set_fs_root() (tab_update.c) has to understand when mountinfo is
necessary (for bind mounts and btrfs).

Reported-by: Stanislav Brabec <sbrabec@suse.cz>
Signed-off-by: Karel Zak <kzak@redhat.com>
---
 libmount/src/tab.c        | 4 +++-
 libmount/src/tab_update.c | 9 +++++++--
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/libmount/src/tab.c b/libmount/src/tab.c
index a7a1b6b..d7a633c 100644
--- a/libmount/src/tab.c
+++ b/libmount/src/tab.c
@@ -1346,6 +1346,8 @@ err:
  *
  * For btrfs subvolumes this function returns NULL, but @fsroot properly set.
  *
+ * If @tb is NULL then defaults to '/'.
+ *
  * Returns: entry from @tb that will be used as a source for @fs if the @fs is
  *          bindmount.
  *
@@ -1432,7 +1434,7 @@ struct libmnt_fs *mnt_table_get_fs_root(struct libmnt_table *tb,
 	/*
 	 * btrfs-subvolume mount -- get subvolume name and use it as a root-fs path
 	 */
-	else if (fstype && (!strcmp(fstype, "btrfs") || !strcmp(fstype, "auto"))) {
+	else if (tb && fstype && (!strcmp(fstype, "btrfs") || !strcmp(fstype, "auto"))) {
 		if (get_btrfs_fs_root(tb, fs, &root) < 0)
 			goto err;
 	}
diff --git a/libmount/src/tab_update.c b/libmount/src/tab_update.c
index 40adba9..631e1cd 100644
--- a/libmount/src/tab_update.c
+++ b/libmount/src/tab_update.c
@@ -357,7 +357,7 @@ static int set_fs_root(struct libmnt_update *upd, struct libmnt_fs *fs,
 {
 	struct libmnt_fs *src_fs;
 	char *fsroot = NULL;
-	const char *src;
+	const char *src, *fstype;
 	int rc = 0;
 
 	DBG(UPDATE, ul_debug("setting FS root"));
@@ -366,16 +366,21 @@ static int set_fs_root(struct libmnt_update *upd, struct libmnt_fs *fs,
 	assert(upd->fs);
 	assert(fs);
 
+	fstype = mnt_fs_get_fstype(fs);
+
 	if (mountflags & MS_BIND) {
 		if (!upd->mountinfo)
 			upd->mountinfo = mnt_new_table_from_file(_PATH_PROC_MOUNTINFO);
-
 		src = mnt_fs_get_srcpath(fs);
 		if (src) {
 			 rc = mnt_fs_set_bindsrc(upd->fs, src);
 			 if (rc)
 				 goto err;
 		}
+
+	} else if (fstype && (strcmp(fstype, "btrfs") == 0 || strcmp(fstype, "auto") == 0)) {
+		if (!upd->mountinfo)
+			upd->mountinfo = mnt_new_table_from_file(_PATH_PROC_MOUNTINFO);
 	}
 
 	src_fs = mnt_table_get_fs_root(upd->mountinfo, fs,
-- 
2.7.3