| Message ID | 20210818060533.3569517-50-keescook@chromium.org |
|---|---|
| State | New |
| Headers | show |
| Series | Introduce strict memcpy() bounds checking | expand |
On 18.08.21 г. 9:05, Kees Cook wrote: > In preparation for FORTIFY_SOURCE performing compile-time and run-time > field bounds checking for memset(), avoid intentionally writing across > neighboring fields. > > Use memset_startat() so memset() doesn't get confused about writing > beyond the destination member that is intended to be the starting point > of zeroing through the end of the struct. > > Cc: Chris Mason <clm@fb.com> > Cc: Josef Bacik <josef@toxicpanda.com> > Cc: David Sterba <dsterba@suse.com> > Cc: linux-btrfs@vger.kernel.org > Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nikolay Borisov <nborisov@suse.com>
On Tue, Aug 17, 2021 at 11:05:19PM -0700, Kees Cook wrote: > In preparation for FORTIFY_SOURCE performing compile-time and run-time > field bounds checking for memset(), avoid intentionally writing across > neighboring fields. > > Use memset_startat() so memset() doesn't get confused about writing > beyond the destination member that is intended to be the starting point > of zeroing through the end of the struct. > > Cc: Chris Mason <clm@fb.com> > Cc: Josef Bacik <josef@toxicpanda.com> > Cc: David Sterba <dsterba@suse.com> > Cc: linux-btrfs@vger.kernel.org > Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c index 702dc5441f03..12ceb14a1141 100644 --- a/fs/btrfs/root-tree.c +++ b/fs/btrfs/root-tree.c @@ -39,10 +39,8 @@ static void btrfs_read_root_item(struct extent_buffer *eb, int slot, need_reset = 1; } if (need_reset) { - memset(&item->generation_v2, 0, - sizeof(*item) - offsetof(struct btrfs_root_item, - generation_v2)); - + /* Clear all members from generation_v2 onwards. */ + memset_startat(item, 0, generation_v2); generate_random_guid(item->uuid); } }
In preparation for FORTIFY_SOURCE performing compile-time and run-time field bounds checking for memset(), avoid intentionally writing across neighboring fields. Use memset_startat() so memset() doesn't get confused about writing beyond the destination member that is intended to be the starting point of zeroing through the end of the struct. Cc: Chris Mason <clm@fb.com> Cc: Josef Bacik <josef@toxicpanda.com> Cc: David Sterba <dsterba@suse.com> Cc: linux-btrfs@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> --- fs/btrfs/root-tree.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)