Li Zefan
2011-Jun-08 08:27 UTC
[PATCH v2] Btrfs: avoid stack bloat in btrfs_ioctl_fs_info()
The size of struct btrfs_ioctl_fs_info_args is as big as 1KB, so don''t declare the variable on stack. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> --- v2: fixed to pass the right size to copy_to_user(). --- fs/btrfs/ioctl.c | 23 ++++++++++++++--------- 1 files changed, 14 insertions(+), 9 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index ac37040..b793d11 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2054,29 +2054,34 @@ static long btrfs_ioctl_rm_dev(struct btrfs_root *root, void __user *arg) static long btrfs_ioctl_fs_info(struct btrfs_root *root, void __user *arg) { - struct btrfs_ioctl_fs_info_args fi_args; + struct btrfs_ioctl_fs_info_args *fi_args; struct btrfs_device *device; struct btrfs_device *next; struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices; + int ret = 0; if (!capable(CAP_SYS_ADMIN)) return -EPERM; - fi_args.num_devices = fs_devices->num_devices; - fi_args.max_id = 0; - memcpy(&fi_args.fsid, root->fs_info->fsid, sizeof(fi_args.fsid)); + fi_args = kzalloc(sizeof(*fi_args), GFP_KERNEL); + if (!fi_args) + return -ENOMEM; + + fi_args->num_devices = fs_devices->num_devices; + memcpy(&fi_args->fsid, root->fs_info->fsid, sizeof(fi_args->fsid)); mutex_lock(&fs_devices->device_list_mutex); list_for_each_entry_safe(device, next, &fs_devices->devices, dev_list) { - if (device->devid > fi_args.max_id) - fi_args.max_id = device->devid; + if (device->devid > fi_args->max_id) + fi_args->max_id = device->devid; } mutex_unlock(&fs_devices->device_list_mutex); - if (copy_to_user(arg, &fi_args, sizeof(fi_args))) - return -EFAULT; + if (copy_to_user(arg, fi_args, sizeof(*fi_args))) + ret = -EFAULT; - return 0; + kfree(fi_args); + return ret; } static long btrfs_ioctl_dev_info(struct btrfs_root *root, void __user *arg) -- 1.7.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at vger.kernel.org/majordomo-info.html
Josef Bacik
2011-Jun-08 13:50 UTC
Re: [PATCH v2] Btrfs: avoid stack bloat in btrfs_ioctl_fs_info()
On 06/08/2011 04:27 AM, Li Zefan wrote:> The size of struct btrfs_ioctl_fs_info_args is as big as 1KB, so > don''t declare the variable on stack. > > Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> > --- >Reviewed-by: Josef Bacik <josef@redhat.com> Thanks, Josef -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at vger.kernel.org/majordomo-info.html