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Btrfs: Null terminate strings passed in from userspace 

The 'char name[BTRFS_PATH_NAME_MAX]' member of struct btrfs_ioctl_vol_args
is passed directly to strlen() after being copied from user. I haven't
verified this, but in theory a userspace program could pass in an
unterminated string and cause a kernel crash as strlen walks off the end of
the array.

This patch terminates the ->name string in all btrfs ioctl functions which
currently use a 'struct btrfs_ioctl_vol_args'. Since the string is now
properly terminated, it's length will never be longer than
BTRFS_PATH_NAME_MAX so that error check has been removed.

By the way, it might be better overall to just have the ioctl pass an
unterminated string + length structure but I didn't bother with that since
it'd change the kernel/user interface.

Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Mark Fasheh 2008-07-24 12:20:14 -04:00 committed by Chris Mason
parent 9652480bf4
commit 5516e5957f
1 changed files with 5 additions and 8 deletions
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13
fs/btrfs/ioctl.c
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@ -310,11 +310,9 @@ static int btrfs_ioctl_resize(struct btrfs_root *root, void __user *arg)
ret = -EFAULT;
goto out;
}
vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
namelen = strlen(vol_args->name);
if (namelen > BTRFS_VOL_NAME_MAX) {
ret = -EINVAL;
goto out;
}
mutex_lock(&root->fs_info->volume_mutex);
sizestr = vol_args->name;
@ -412,11 +410,8 @@ static noinline int btrfs_ioctl_snap_create(struct btrfs_root *root,
goto out;
}
vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
namelen = strlen(vol_args->name);
if (namelen > BTRFS_VOL_NAME_MAX) {
ret = -EINVAL;
goto out;
}
if (strchr(vol_args->name, '/')) {
ret = -EINVAL;
goto out;
@ -487,6 +482,7 @@ long btrfs_ioctl_add_dev(struct btrfs_root *root, void __user *arg)
ret = -EFAULT;
goto out;
}
vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
ret = btrfs_init_new_device(root, vol_args->name);
out:
@ -508,6 +504,7 @@ long btrfs_ioctl_rm_dev(struct btrfs_root *root, void __user *arg)
ret = -EFAULT;
goto out;
}
vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
ret = btrfs_rm_device(root, vol_args->name);
out: