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authorOmar Sandoval <osandov@fb.com>2018-05-22 15:44:01 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-06-26 08:08:07 +0800
commit9bb94d81206b4980f5c547c07dfdf7a912b73f7b (patch)
parent52ea25b2b88587302a03b2ae8f2dd9b546337cc5 (diff)
Btrfs: fix memory and mount leak in btrfs_ioctl_rm_dev_v2()
commit fd4e994bd1f9dc9628e168a7f619bf69f6984635 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 4 insertions, 2 deletions
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 9ac8f3ded704..cbf512b64597 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2708,8 +2708,10 @@ static long btrfs_ioctl_rm_dev_v2(struct file *file, void __user *arg)
/* Check for compatibility reject unknown flags */
- if (vol_args->flags & ~BTRFS_VOL_ARG_V2_FLAGS_SUPPORTED)
- return -EOPNOTSUPP;
+ if (vol_args->flags & ~BTRFS_VOL_ARG_V2_FLAGS_SUPPORTED) {
+ ret = -EOPNOTSUPP;
+ goto out;
+ }
if (atomic_xchg(&root->fs_info->mutually_exclusive_operation_running,
1)) {