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H A Dioctl.cfd4e994b Tue May 22 17:44:01 CDT 2018 Omar Sandoval <osandov@fb.com> Btrfs: fix memory and mount leak in btrfs_ioctl_rm_dev_v2()

If we have invalid flags set, when we error out we must drop our writer
counter and free the buffer we allocated for the arguments. This bug is
trivially reproduced with the following program on 4.7+:

#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <linux/btrfs.h>
#include <linux/btrfs_tree.h>

int main(int argc, char **argv)
{
struct btrfs_ioctl_vol_args_v2 vol_args = {
.flags = UINT64_MAX,
};
int ret;
int fd;

if (argc != 2) {
fprintf(stderr, "usage: %s PATH\n", argv[0]);
return EXIT_FAILURE;
}

fd = open(argv[1], O_WRONLY);
if (fd == -1) {
perror("open");
return EXIT_FAILURE;
}

ret = ioctl(fd, BTRFS_IOC_RM_DEV_V2, &vol_args);
if (ret == -1)
perror("ioctl");

close(fd);
return EXIT_SUCCESS;
}

When unmounting the filesystem, we'll hit the
WARN_ON(mnt_get_writers(mnt)) in cleanup_mnt() and also may prevent the
filesystem to be remounted read-only as the writer count will stay
lifted.

Fixes: 6b526ed70cf1 ("btrfs: introduce device delete by devid")
CC: stable@vger.kernel.org # 4.9+
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Su Yue <suy.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
fd4e994b Tue May 22 17:44:01 CDT 2018 Omar Sandoval <osandov@fb.com> Btrfs: fix memory and mount leak in btrfs_ioctl_rm_dev_v2()

If we have invalid flags set, when we error out we must drop our writer
counter and free the buffer we allocated for the arguments. This bug is
trivially reproduced with the following program on 4.7+:

#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <linux/btrfs.h>
#include <linux/btrfs_tree.h>

int main(int argc, char **argv)
{
struct btrfs_ioctl_vol_args_v2 vol_args = {
.flags = UINT64_MAX,
};
int ret;
int fd;

if (argc != 2) {
fprintf(stderr, "usage: %s PATH\n", argv[0]);
return EXIT_FAILURE;
}

fd = open(argv[1], O_WRONLY);
if (fd == -1) {
perror("open");
return EXIT_FAILURE;
}

ret = ioctl(fd, BTRFS_IOC_RM_DEV_V2, &vol_args);
if (ret == -1)
perror("ioctl");

close(fd);
return EXIT_SUCCESS;
}

When unmounting the filesystem, we'll hit the
WARN_ON(mnt_get_writers(mnt)) in cleanup_mnt() and also may prevent the
filesystem to be remounted read-only as the writer count will stay
lifted.

Fixes: 6b526ed70cf1 ("btrfs: introduce device delete by devid")
CC: stable@vger.kernel.org # 4.9+
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Su Yue <suy.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>