From: Kees Cook keescook@chromium.org
commit cf8aa9bf97cadf85745506c6a3e244b22c268d63 upstream.
The "buf" flexible array needs to be the memcpy() destination to avoid false positive run-time warning from the recent FORTIFY_SOURCE hardening:
memcpy: detected field-spanning write (size 93) of single field "&fh->fb" at fs/overlayfs/export.c:799 (size 21)
Reported-by: syzbot+9d14351a171d0d1c7955@syzkaller.appspotmail.com Link: https://lore.kernel.org/all/000000000000763a6c05e95a5985@google.com/ Signed-off-by: Kees Cook keescook@chromium.org Reviewed-by: Gustavo A. R. Silva gustavoars@kernel.org Signed-off-by: Miklos Szeredi mszeredi@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/overlayfs/export.c | 2 +- fs/overlayfs/overlayfs.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)
--- a/fs/overlayfs/export.c +++ b/fs/overlayfs/export.c @@ -791,7 +791,7 @@ static struct ovl_fh *ovl_fid_to_fh(stru return ERR_PTR(-ENOMEM);
/* Copy unaligned inner fh into aligned buffer */ - memcpy(&fh->fb, fid, buflen - OVL_FH_WIRE_OFFSET); + memcpy(fh->buf, fid, buflen - OVL_FH_WIRE_OFFSET); return fh; }
--- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -107,7 +107,7 @@ struct ovl_fh { u8 padding[3]; /* make sure fb.fid is 32bit aligned */ union { struct ovl_fb fb; - u8 buf[0]; + DECLARE_FLEX_ARRAY(u8, buf); }; } __packed;