[btrfs-progs] [bug][patch] Leaking file handle in scrub_fs_info()

[Goffredo Baroncelli <kreijack@libero.it>]

Hi Jan,

I was giving a look to the function scrub_fs_info( ), and to me it seems
that could be a potential file handle leaking problem.


In fact:

static int scrub_fs_info(int fd, char *path,
                    struct btrfs_ioctl_fs_info_args *fi_args,
                    struct btrfs_ioctl_dev_info_args **di_ret)
{

[...]

        ret = ioctl(fd, BTRFS_IOC_FS_INFO, fi_args);
        if (ret && errno == EINVAL) {
                /* path is no mounted btrfs. try if it's a device */
[...]
                close(fd);			<--- Here the
						     file handle is
						     closed

                fd = open_file_or_dir(mp);	<--- then it is
						     re-opened
                if (fd < 0)
                        return -errno;
        } else if (ret) {
                return -errno;
        }
[...]

But in the rest of the function:
a) the file handle is not closed
b) the (new) file handle isn't returned

The function "scrub_fs_info()" is called from the functions
1) cmd_scrub_status(), which doesn't use the file handle after the call
to the cmd_scrub_status() [except for a close()]. So no problem at all.
2) scrub_start(), which uses the file handle after the call to the
cmd_scrub_status() functions.

My suggestions is to change scrub_fs_info() to accept only the path.
Then it open (and closes) its own (and private) the file descriptor.

Instead scrub_start(), opens a file descriptor after the call to the
scrub_fs_info() function.

What do you think ?

BR
G.Baroncelli

You can pull the patch below from

	http://cassiopea.homelinux.net/git/btrfs-progs-unstable.git

branch

	fd-leaking

-----

diff --git a/cmds-scrub.c b/cmds-scrub.c
index c4503f4..486768c 100644
--- a/cmds-scrub.c
+++ b/cmds-scrub.c
@@ -979,19 +979,26 @@ static int scrub_device_info(int fd, u64 devid,
 	return ret ? -errno : 0;
 }

-static int scrub_fs_info(int fd, char *path,
+static int scrub_fs_info( char *path,
 				struct btrfs_ioctl_fs_info_args *fi_args,
 				struct btrfs_ioctl_dev_info_args **di_ret)
 {
 	int ret = 0;
 	int ndevs = 0;
 	int i = 1;
+	int fd;
 	struct btrfs_fs_devices *fs_devices_mnt = NULL;
 	struct btrfs_ioctl_dev_info_args *di_args;
 	char mp[BTRFS_PATH_NAME_MAX + 1];

 	memset(fi_args, 0, sizeof(*fi_args));

+	fd  = open_file_or_dir(path);
+	if (fd < 0) {
+		fprintf(stderr, "ERROR: can't access to '%s'\n", path);
+		return -1;
+	}
+
 	ret = ioctl(fd, BTRFS_IOC_FS_INFO, fi_args);
 	if (ret && errno == EINVAL) {
 		/* path is no mounted btrfs. try if it's a device */
@@ -1010,28 +1017,36 @@ static int scrub_fs_info(int fd, char *path,
 		if (fd < 0)
 			return -errno;
 	} else if (ret) {
+		close(fd);
 		return -errno;
 	}

-	if (!fi_args->num_devices)
+	if (!fi_args->num_devices){
+		close(fd);
 		return 0;
+	}

 	di_args = *di_ret = malloc(fi_args->num_devices * sizeof(*di_args));
-	if (!di_args)
+	if (!di_args){
+		close(fd);
 		return -errno;
+	}

 	for (; i <= fi_args->max_id; ++i) {
 		BUG_ON(ndevs >= fi_args->num_devices);
 		ret = scrub_device_info(fd, i, &di_args[ndevs]);
 		if (ret == -ENODEV)
 			continue;
-		if (ret)
+		if (ret){
+			close(fd);
 			return ret;
+		}
 		++ndevs;
 	}

 	BUG_ON(ndevs == 0);

+	close(fd);
 	return 0;
 }

@@ -1155,7 +1170,7 @@ static int scrub_start(int argc, char **argv, int
resume)
 		return 12;
 	}

-	ret = scrub_fs_info(fdmnt, path, &fi_args, &di_args);
+	ret = scrub_fs_info(path, &fi_args, &di_args);
 	if (ret) {
 		ERR(!do_quiet, "ERROR: getting dev info for scrub failed: "
 		    "%s\n", strerror(-ret));
@@ -1586,7 +1601,6 @@ static int cmd_scrub_status(int argc, char **argv)
 		.sun_family = AF_UNIX,
 	};
 	int ret;
-	int fdmnt;
 	int i;
 	int print_raw = 0;
 	int do_stats_per_dev = 0;
@@ -1615,13 +1629,7 @@ static int cmd_scrub_status(int argc, char **argv)

 	path = argv[optind];

-	fdmnt = open_file_or_dir(path);
-	if (fdmnt < 0) {
-		fprintf(stderr, "ERROR: can't access to '%s'\n", path);
-		return 12;
-	}
-
-	ret = scrub_fs_info(fdmnt, path, &fi_args, &di_args);
+	ret = scrub_fs_info(path, &fi_args, &di_args);
 	if (ret) {
 		fprintf(stderr, "ERROR: getting dev info for scrub failed: "
 				"%s\n", strerror(-ret));
@@ -1698,7 +1706,6 @@ static int cmd_scrub_status(int argc, char **argv)
 out:
 	free_history(past_scrubs);
 	free(di_args);
-	close(fdmnt);
 	if (fdres > -1)
 		close(fdres);