Thanks Lorenzo,

I think that ovn_dp_group() functions should take dynamic bitmaps as
arguments instead of a static bitmap and a size. This way we ensure we
always use the correct capacity for the bitmap.

If you did this, I think there would be no need for the
dynamic_bitmap_clone_from_bitmap() function as well.

On Wed, Nov 12, 2025 at 10:02 AM Lorenzo Bianconi via dev
<[email protected]> wrote:
>
> This allow easy bitmap resizing to avoid the following address sanitizer
> crashes if we are exceeding bitmap allocated size. This issue can occurs
> since IP lflow support for logical routers does not take into account
> ovn_dp_group bitmap resize.
>
> =================================================================
> ==52991==ERROR: AddressSanitizer: heap-buffer-overflow on address 
> 0x7bce82430100 at pc 0x0000004eae83 bp 0x7ffd7306f980 sp 0x7ffd7306f978
> READ of size 8 at 0x7bce82430100 thread T0
>     #0 0x0000004eae82 in bitmap_is_set ovn/ovs/lib/bitmap.h:91
>     #1 0x0000004eae82 in lflow_table_add_lflow northd/lflow-mgr.c:765
>     #2 0x00000046c075 in build_adm_ctrl_flows_for_lrouter 
> northd/northd.c:13759
>     #3 0x00000046c075 in build_lswitch_and_lrouter_iterate_by_lr 
> northd/northd.c:18591
>     #4 0x000000479805 in lflow_handle_northd_lr_changes northd/northd.c:19299
>     #5 0x00000049bcc0 in lflow_northd_handler northd/en-lflow.c:158
>     #6 0x000000508895 in engine_compute lib/inc-proc-eng.c:474
>     #7 0x000000508895 in engine_run_node lib/inc-proc-eng.c:546
>     #8 0x000000508895 in engine_run lib/inc-proc-eng.c:575
>     #9 0x0000004e0cff in inc_proc_northd_run northd/inc-proc-northd.c:602
>     #10 0x0000004077b4 in main northd/ovn-northd.c:1104
>     #11 0x7fae83523574 in __libc_start_call_main (/lib64/libc.so.6+0x3574) 
> (BuildId: 48c4b9b1efb1df15da8e787f489128bf31893317)
>     #12 0x7fae83523627 in __libc_start_main@GLIBC_2.2.5 
> (/lib64/libc.so.6+0x3627) (BuildId: 48c4b9b1efb1df15da8e787f489128bf31893317)
>     #13 0x00000040ae74 in _start (ovn/northd/ovn-northd+0x40ae74) (BuildId: 
> 5373e3f3823362d2c1a220082395cf8a9aae28bc)
>
> 0x7bce82430100 is located 0 bytes after 16-byte region 
> [0x7bce824300f0,0x7bce82430100)
> allocated by thread T0 here:
>     #0 0x7fae83ee68a3 in calloc (/lib64/libasan.so.8+0xe68a3) (BuildId: 
> cab80046dbc1c97c6e14490acc37d079701f8d9a)
>     #1 0x00000077873e in xcalloc__ lib/util.c:125
>     #2 0x00000077873e in xzalloc__ lib/util.c:135
>     #3 0x00000077873e in xzalloc lib/util.c:169
>     #4 0x0000004ea05b in bitmap_allocate ovn/ovs/lib/bitmap.h:51
>     #5 0x0000004ea05b in ovn_lflow_init northd/lflow-mgr.c:901
>     #6 0x0000004ea05b in do_ovn_lflow_add northd/lflow-mgr.c:1028
>     #7 0x0000004ea05b in lflow_table_add_lflow northd/lflow-mgr.c:730
>     #8 0x00000046c075 in build_adm_ctrl_flows_for_lrouter 
> northd/northd.c:13759
>     #9 0x00000046c075 in build_lswitch_and_lrouter_iterate_by_lr 
> northd/northd.c:18591
>     #10 0x000000479805 in lflow_handle_northd_lr_changes northd/northd.c:19299
>     #11 0x00000049bcc0 in lflow_northd_handler northd/en-lflow.c:158
>     #12 0x000000508895 in engine_compute lib/inc-proc-eng.c:474
>     #13 0x000000508895 in engine_run_node lib/inc-proc-eng.c:546
>     #14 0x000000508895 in engine_run lib/inc-proc-eng.c:575
>     #15 0x0000004e0cff in inc_proc_northd_run northd/inc-proc-northd.c:602
>     #16 0x0000004077b4 in main northd/ovn-northd.c:1104
>     #17 0x7fae83523574 in __libc_start_call_main (/lib64/libc.so.6+0x3574) 
> (BuildId: 48c4b9b1efb1df15da8e787f489128bf31893317)
>     #18 0x7fae83523627 in __libc_start_main@GLIBC_2.2.5 
> (/lib64/libc.so.6+0x3627) (BuildId: 48c4b9b1efb1df15da8e787f489128bf31893317)
>     #19 0x00000040ae74 in _start (ovn/northd/ovn-northd+0x40ae74) (BuildId: 
> 5373e3f3823362d2c1a220082395cf8a9aae28bc)
>
> Fixes: 9ec96d0d85b6 ("northd: Add and delete logical routers in en-lflow 
> engine node.")
> Fixes: f22a005f8935 ("northd: Convert datapath array into vector.")
> Reported-at: https://issues.redhat.com/browse/FDP-2643
> Signed-off-by: Lorenzo Bianconi <[email protected]>
> ---
>  lib/ovn-util.h      |  8 ++++++++
>  northd/lflow-mgr.c  |  8 +++++---
>  northd/lflow-mgr.h  |  6 +++---
>  tests/ovn-northd.at | 34 ++++++++++++++++++++++++++++++++++
>  4 files changed, 50 insertions(+), 6 deletions(-)
>
> diff --git a/lib/ovn-util.h b/lib/ovn-util.h
> index aa1a878bb..eda2bd4a0 100644
> --- a/lib/ovn-util.h
> +++ b/lib/ovn-util.h
> @@ -586,6 +586,14 @@ dynamic_bitmap_clone_map(struct dynamic_bitmap *db)
>      return bitmap_clone(db->map, db->capacity);
>  }
>
> +static inline void
> +dynamic_bitmap_clone_from_bitmap(struct dynamic_bitmap *db,
> +                                 const unsigned long *bitmap, size_t n_bits)
> +{
> +    db->map = bitmap_clone(bitmap, n_bits);
> +    db->capacity = n_bits;
> +}
> +
>  static inline size_t
>  dynamic_bitmap_scan(struct dynamic_bitmap *dp, bool target, size_t start)
>  {
> diff --git a/northd/lflow-mgr.c b/northd/lflow-mgr.c
> index 3af36c7fd..1a79d1ce9 100644
> --- a/northd/lflow-mgr.c
> +++ b/northd/lflow-mgr.c
> @@ -836,7 +836,7 @@ ovn_dp_group_create(struct ovsdb_idl_txn *ovnsb_txn,
>      bitmap_free(dpg_bitmap);
>
>      dpg = xzalloc(sizeof *dpg);
> -    dpg->bitmap = bitmap_clone(desired_bitmap, bitmap_len);
> +    dynamic_bitmap_clone_from_bitmap(&dpg->bitmap, desired_bitmap, 
> bitmap_len);
>      if (!update_dp_group) {
>          dpg->dp_group = sb_group;
>      } else {
> @@ -1239,7 +1239,9 @@ ovn_dp_group_find(const struct hmap *dp_groups,
>      struct ovn_dp_group *dpg;
>
>      HMAP_FOR_EACH_WITH_HASH (dpg, node, hash, dp_groups) {
> -        if (bitmap_equal(dpg->bitmap, dpg_bitmap, bitmap_len)) {
> +        if (bitmap_equal(dpg->bitmap.map, dpg_bitmap,
> +                         MIN(bitmap_len, dpg->bitmap.capacity))) {
> +            dynamic_bitmap_realloc(&dpg->bitmap, bitmap_len);
>              return dpg;
>          }
>      }
> @@ -1269,7 +1271,7 @@ ovn_dp_group_release(struct hmap *dp_groups, struct 
> ovn_dp_group *dpg)
>  static void
>  ovn_dp_group_destroy(struct ovn_dp_group *dpg)
>  {
> -    bitmap_free(dpg->bitmap);
> +    dynamic_bitmap_free(&dpg->bitmap);
>      free(dpg);
>  }
>
> diff --git a/northd/lflow-mgr.h b/northd/lflow-mgr.h
> index 91708c8a9..2840e3228 100644
> --- a/northd/lflow-mgr.h
> +++ b/northd/lflow-mgr.h
> @@ -159,7 +159,7 @@ void lflow_table_add_lflow(struct lflow_table *, const 
> struct ovn_datapath *,
>  struct sbrec_logical_dp_group;
>
>  struct ovn_dp_group {
> -    unsigned long *bitmap;
> +    struct dynamic_bitmap bitmap;
>      const struct sbrec_logical_dp_group *dp_group;
>      struct uuid dpg_uuid;
>      struct hmap_node node;
> @@ -198,9 +198,9 @@ dec_ovn_dp_group_ref(struct hmap *dp_groups, struct 
> ovn_dp_group *dpg)
>
>      if (!dpg->refcnt) {
>          hmap_remove(dp_groups, &dpg->node);
> -        free(dpg->bitmap);
> +        dynamic_bitmap_free(&dpg->bitmap);
>          free(dpg);
>      }
>  }
>
> -#endif /* LFLOW_MGR_H */
> \ No newline at end of file
> +#endif /* LFLOW_MGR_H */
> diff --git a/tests/ovn-northd.at b/tests/ovn-northd.at
> index 448bc66ae..a88b71ca8 100644
> --- a/tests/ovn-northd.at
> +++ b/tests/ovn-northd.at
> @@ -3026,6 +3026,40 @@ OVS_WAIT_UNTIL([grep "all port tunnel ids exhausted" 
> northd/ovn-northd.log])
>  AT_CLEANUP
>  ])
>
> +OVN_FOR_EACH_NORTHD_NO_HV([
> +AT_SETUP([check LS/LR single line configuration])
> +ovn_start
> +
> +cmd=""
> +for i in {1..2048..1}; do
> +    cmd="${cmd} -- ls-add lsw-${i}"
> +    if test $(($i % 100)) -eq 0; then
> +        check ovn-nbctl $cmd
> +        cmd=""
> +    fi
> +done
> +
> +check ovn-nbctl --wait=sb $cmd
> +
> +check_row_count nb:Logical_Switch 2048
> +wait_row_count sb:Datapath_Binding 2048
> +
> +cmd=""
> +for i in {1..2048..1}; do
> +    cmd="${cmd} -- lr-add lr-${i}"
> +    if test $(($i % 100)) -eq 0; then
> +        check ovn-nbctl $cmd
> +        cmd=""
> +    fi
> +done
> +
> +check ovn-nbctl --wait=sb $cmd
> +check_row_count nb:Logical_Router 2048
> +wait_row_count sb:Datapath_Binding 4096
> +
> +AT_CLEANUP
> +])
> +
>  OVN_FOR_EACH_NORTHD_NO_HV([
>  AT_SETUP([check VXLAN encap in IC-mode])
>  ovn_start
> --
> 2.51.1
>
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>

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