From 5516e5957f4b99b19fffffa53bf9fbe7cc793249 Mon Sep 17 00:00:00 2001 From: Mark Fasheh Date: Thu, 24 Jul 2008 12:20:14 -0400 Subject: [PATCH] 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 Signed-off-by: Chris Mason --- fs/btrfs/ioctl.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 7d40778..5e62774 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -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: -- 2.7.4