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libbtrfsutil: subvolume: use helpers to access search header

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The test cli-tests/008-subvolume-get-set-default fails when compiled
with 'D=ubsan', the access to search header items does not follow the
type alignment, so use the accessors.

The error:

  subvolume get-default: default id is not 256, but
	  libbtrfsutil/subvolume.c:361:13: runtime error: member access within
	  misaligned address 0x7ffc147e4b6f for type 'const struct
	  btrfs_ioctl_search_header', which requires 8 byte alignment

Note that using the accessors does not fix the ubsan warning, as it
warns on taking the address of a member whose _base_ type is unaligned,
ie. it's the 'sh'.

Fixing that would need to play tricks with pointers to do &sh->type
manually, but to avoid triggering ubsan.

Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2019-07-04 14:30:30 +02:00
parent db1246039d
commit 4d29e37947
1 changed files with 10 additions and 9 deletions
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19
libbtrfsutil/subvolume.c
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@ -358,7 +358,7 @@ static enum btrfs_util_error get_subvolume_info_privileged(int fd, uint64_t id,
} }
header = (struct btrfs_ioctl_search_header *)(search.buf + buf_off); header = (struct btrfs_ioctl_search_header *)(search.buf + buf_off);
if (header->type == BTRFS_ROOT_ITEM_KEY) { if (btrfs_search_header_type(header) == BTRFS_ROOT_ITEM_KEY) {
if (subvol) { if (subvol) {
const struct btrfs_root_item *root; const struct btrfs_root_item *root;
@ -367,12 +367,12 @@ static enum btrfs_util_error get_subvolume_info_privileged(int fd, uint64_t id,
} }
need_root_item = false; need_root_item = false;
search.key.min_type = BTRFS_ROOT_BACKREF_KEY; search.key.min_type = BTRFS_ROOT_BACKREF_KEY;
} else if (header->type == BTRFS_ROOT_BACKREF_KEY) { } else if (btrfs_search_header_type(header) == BTRFS_ROOT_BACKREF_KEY) {
if (subvol) { if (subvol) {
const struct btrfs_root_ref *ref; const struct btrfs_root_ref *ref;
ref = (const struct btrfs_root_ref *)(header + 1); ref = (const struct btrfs_root_ref *)(header + 1);
subvol->parent_id = header->offset; subvol->parent_id = btrfs_search_header_offset(header);
subvol->dir_id = le64_to_cpu(ref->dirid); subvol->dir_id = le64_to_cpu(ref->dirid);
} }
need_root_backref = false; need_root_backref = false;
@ -380,7 +380,7 @@ static enum btrfs_util_error get_subvolume_info_privileged(int fd, uint64_t id,
} }
items_pos++; items_pos++;
buf_off += sizeof(*header) + header->len; buf_off += sizeof(*header) + btrfs_search_header_len(header);
} }
return BTRFS_UTIL_OK; return BTRFS_UTIL_OK;
@ -1366,7 +1366,7 @@ static enum btrfs_util_error build_subvol_path_privileged(struct btrfs_util_subv
size_t *path_len_ret) size_t *path_len_ret)
{ {
struct btrfs_ioctl_ino_lookup_args lookup = { struct btrfs_ioctl_ino_lookup_args lookup = {
.treeid = header->objectid, .treeid = btrfs_search_header_objectid(header),
.objectid = le64_to_cpu(ref->dirid), .objectid = le64_to_cpu(ref->dirid),
}; };
int ret; int ret;
@ -1442,11 +1442,11 @@ static enum btrfs_util_error subvolume_iterator_next_tree_search(struct btrfs_ut
header = (struct btrfs_ioctl_search_header *)(top->search.buf + top->buf_off); header = (struct btrfs_ioctl_search_header *)(top->search.buf + top->buf_off);
top->items_pos++; top->items_pos++;
top->buf_off += sizeof(*header) + header->len; top->buf_off += sizeof(*header) + btrfs_search_header_len(header);
top->search.key.min_offset = header->offset + 1; top->search.key.min_offset = btrfs_search_header_offset(header) + 1;
/* This shouldn't happen, but handle it just in case. */ /* This shouldn't happen, but handle it just in case. */
if (header->type != BTRFS_ROOT_REF_KEY) if (btrfs_search_header_type(header) != BTRFS_ROOT_REF_KEY)
continue; continue;
ref = (struct btrfs_root_ref *)(header + 1); ref = (struct btrfs_root_ref *)(header + 1);
@ -1456,7 +1456,8 @@ static enum btrfs_util_error subvolume_iterator_next_tree_search(struct btrfs_ut
if (err) if (err)
return err; return err;
err = append_to_search_stack(iter, header->offset, path_len); err = append_to_search_stack(iter,
btrfs_search_header_offset(header), path_len);
if (err) if (err)
return err; return err;