On Wed, Jun 19, 2024 at 3:19 PM Mike Pattrick <[email protected]> wrote:

> When compiling with '-fsanitize=address,undefined', the "ovs-ofctl
> ct-flush" test will yield the following undefined behavior flagged by
> UBSan. This problem is caused by the fact that 128bit property put/parse
> functions weren't adding appropriate padding before writing or reading
> the value.
>
> This patch uses get_32aligned_* functions to copy the bytes as they are
> aligned.
>
> lib/ofp-prop.c:277:14: runtime error: load of misaligned address
> 0x60600000687c for type 'union ovs_be128', which requires 8 byte
> alignment
> 0x60600000687c: note: pointer points here
>   00 05 00 14 00 00 00 00  00 00 00 00 00 00 00 00  00 ff ab 00
>               ^
>     0: in ofpprop_parse_u128 lib/ofp-prop.c:277
>     1: in ofp_ct_match_decode lib/ofp-ct.c:525
>     2: in ofp_print_nxt_ct_flush lib/ofp-print.c:959
>     3: in ofp_to_string__ lib/ofp-print.c:1206
>     4: in ofp_to_string lib/ofp-print.c:1264
>     5: in ofp_print lib/ofp-print.c:1308
>     6: in ofctl_ofp_print utilities/ovs-ofctl.c:4899
>     7: in ovs_cmdl_run_command__ lib/command-line.c:247
>     8: in ovs_cmdl_run_command lib/command-line.c:278
>     9: in main utilities/ovs-ofctl.c:186
>
> Signed-off-by: Mike Pattrick <[email protected]>
> ---
> v2: removed memcpy
> v3: fixed checkpatch
> ---
>  lib/ofp-prop.c | 17 ++++++++++-------
>  1 file changed, 10 insertions(+), 7 deletions(-)
>
> diff --git a/lib/ofp-prop.c b/lib/ofp-prop.c
> index 0a685750c..0e54543bd 100644
> --- a/lib/ofp-prop.c
> +++ b/lib/ofp-prop.c
> @@ -21,6 +21,7 @@
>  #include "openvswitch/ofp-errors.h"
>  #include "openvswitch/ofp-prop.h"
>  #include "openvswitch/vlog.h"
> +#include "unaligned.h"
>  #include "util.h"
>  #include "uuid.h"
>
> @@ -190,11 +191,12 @@ ofpprop_parse_be64(const struct ofpbuf *property,
> ovs_be64 *value)
>  enum ofperr
>  ofpprop_parse_be128(const struct ofpbuf *property, ovs_be128 *value)
>  {
> -    ovs_be128 *p = property->msg;
> +    ovs_32aligned_be128 *p = property->msg;
> +
>      if (ofpbuf_msgsize(property) != sizeof *p) {
>          return OFPERR_OFPBPC_BAD_LEN;
>      }
> -    *value = *p;
> +    *value = get_32aligned_be128(p);
>      return 0;
>  }
>
> @@ -270,12 +272,13 @@ ofpprop_parse_u64(const struct ofpbuf *property,
> uint64_t *value)
>  enum ofperr
>  ofpprop_parse_u128(const struct ofpbuf *property, ovs_u128 *value)
>  {
> -    ovs_be128 *p = property->msg;
> -    if (ofpbuf_msgsize(property) != sizeof *p) {
> -        return OFPERR_OFPBPC_BAD_LEN;
> +    enum ofperr error = ofpprop_parse_be128(property, (ovs_be128 *)
> value);
> +
> +    if (!error) {
> +        *value = ntoh128(*(ovs_be128 *) value);
>      }
> -    *value = ntoh128(*p);
> -    return 0;
> +
> +    return error;
>  }
>
>  /* Attempts to parse 'property' as a property containing a UUID.  If
> --
> 2.39.3
>
> _______________________________________________
> dev mailing list
> [email protected]
> https://mail.openvswitch.org/mailman/listinfo/ovs-dev
>
>
Looks good to me, thanks.

Acked-by: Ales Musil <[email protected]>

-- 

Ales Musil

Senior Software Engineer - OVN Core

Red Hat EMEA <https://www.redhat.com>

[email protected]
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