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[FRR]Adding fix for memory leak seen with BGP community (sonic-net#18606
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Porting PR sonic-net#18272 to 202311.

Why I did it
Porting fix for FRRouting/frr#15459

Adding patch for PR FRRouting/frr#15466

Work item tracking
Microsoft ADO (number only):
How I did it
Ported the fix FRRouting/frr#15466 to 8.5.1

How to verify it
Running the test_stress_route and ensure no memory leak
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dgsudharsan authored Apr 18, 2024
1 parent baf6f62 commit 2f9bc00
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303 changes: 303 additions & 0 deletions src/sonic-frr/patch/0037-bgp-community-memory-leak-fix.patch
Original file line number Diff line number Diff line change
@@ -0,0 +1,303 @@
From 2b8e4e4b93a78e5884e2e5b97050b4ea3843e2e0 Mon Sep 17 00:00:00 2001
From: Donald Sharp <sharpd@nvidia.com>
Date: Thu, 7 Mar 2024 22:18:18 -0500
Subject: [PATCH 1/2] bgpd: Combined patch to clean up filter leaks

Customer has this valgrind trace:

Direct leak of 2829120 byte(s) in 70728 object(s) allocated from:
0 in community_new ../bgpd/bgp_community.c:39
1 in community_uniq_sort ../bgpd/bgp_community.c:170
2 in route_set_community ../bgpd/bgp_routemap.c:2342
3 in route_map_apply_ext ../lib/routemap.c:2673
4 in subgroup_announce_check ../bgpd/bgp_route.c:2367
5 in subgroup_process_announce_selected ../bgpd/bgp_route.c:2914
6 in group_announce_route_walkcb ../bgpd/bgp_updgrp_adv.c:199
7 in hash_walk ../lib/hash.c:285
8 in update_group_af_walk ../bgpd/bgp_updgrp.c:2061
9 in group_announce_route ../bgpd/bgp_updgrp_adv.c:1059
10 in bgp_process_main_one ../bgpd/bgp_route.c:3221
11 in bgp_process_wq ../bgpd/bgp_route.c:3221
12 in work_queue_run ../lib/workqueue.c:282

The above leak detected by valgrind was from a screenshot so I copied it
by hand. Any mistakes in line numbers are purely from my transcription.
Additionally this is against a slightly modified 8.5.1 version of FRR.
Code inspection of 8.5.1 -vs- latest master shows the same problem
exists. Code should be able to be followed from there to here.

What is happening:

There is a route-map being applied that modifes the outgoing community
to a peer. This is saved in the attr copy created in
subgroup_process_announce_selected. This community pointer is not
interned. So the community->refcount is still 0. Normally when
a prefix is announced, the attr and the prefix are placed on a
adjency out structure where the attribute is interned. This will
cause the community to be saved in the community hash list as well.
In a non-normal operation when the decision to send is aborted after
the route-map application, the attribute is just dropped and the
pointer to the community is just dropped too, leading to situations
where the memory is leaked. The usage of bgp suppress-fib would
would be a case where the community is caused to be leaked.
Additionally the previous commit where an unsuppress-map is used
to modify the outgoing attribute but since unsuppress-map was
not considered part of outgoing policy the attribute would be dropped as
well. This pointer drop also extends to any dynamically allocated
memory saved by the attribute pointer that was not interned yet as well.

So let's modify the return case where the decision is made to
not send the prefix to the peer to always just flush the attribute
to ensure memory is not leaked.

Fixes: #15459
Signed-off-by: Donald Sharp <sharpd@nvidia.com>
---
bgpd/bgp_conditional_adv.c | 5 +++--
bgpd/bgp_route.c | 19 +++++++++++------
bgpd/bgp_updgrp.h | 2 +-
bgpd/bgp_updgrp_adv.c | 53 ++++++++++++++++++++++++++--------------------
4 files changed, 47 insertions(+), 32 deletions(-)

diff --git a/bgpd/bgp_conditional_adv.c b/bgpd/bgp_conditional_adv.c
index 4ad00ed121..89ea85ff46 100644
--- a/bgpd/bgp_conditional_adv.c
+++ b/bgpd/bgp_conditional_adv.c
@@ -134,8 +134,9 @@ static void bgp_conditional_adv_routes(struct peer *peer, afi_t afi,
if (update_type == UPDATE_TYPE_ADVERTISE &&
subgroup_announce_check(dest, pi, subgrp, dest_p,
&attr, &advmap_attr)) {
- bgp_adj_out_set_subgroup(dest, subgrp, &attr,
- pi);
+ if (!bgp_adj_out_set_subgroup(dest, subgrp,
+ &attr, pi))
+ bgp_attr_flush(&attr);
} else {
/* If default originate is enabled for
* the peer, do not send explicit
diff --git a/bgpd/bgp_route.c b/bgpd/bgp_route.c
index a7a5c9849a..157bfa8a2b 100644
--- a/bgpd/bgp_route.c
+++ b/bgpd/bgp_route.c
@@ -2917,16 +2917,23 @@ void subgroup_process_announce_selected(struct update_subgroup *subgrp,
* in FIB, then it is advertised
*/
if (advertise) {
- if (!bgp_check_withdrawal(bgp, dest))
- bgp_adj_out_set_subgroup(
- dest, subgrp, &attr, selected);
- else
+ if (!bgp_check_withdrawal(bgp, dest)) {
+ if (!bgp_adj_out_set_subgroup(
+ dest, subgrp, &attr,
+ selected))
+ bgp_attr_flush(&attr);
+ } else {
bgp_adj_out_unset_subgroup(
dest, subgrp, 1, addpath_tx_id);
- }
- } else
+ bgp_attr_flush(&attr);
+ }
+ } else
+ bgp_attr_flush(&attr);
+ } else {
bgp_adj_out_unset_subgroup(dest, subgrp, 1,
addpath_tx_id);
+ bgp_attr_flush(&attr);
+ }
}

/* If selected is NULL we must withdraw the path using addpath_tx_id */
diff --git a/bgpd/bgp_updgrp.h b/bgpd/bgp_updgrp.h
index e27c1e7b67..b7b6aa07e9 100644
--- a/bgpd/bgp_updgrp.h
+++ b/bgpd/bgp_updgrp.h
@@ -458,7 +458,7 @@ extern struct bgp_adj_out *bgp_adj_out_alloc(struct update_subgroup *subgrp,
extern void bgp_adj_out_remove_subgroup(struct bgp_dest *dest,
struct bgp_adj_out *adj,
struct update_subgroup *subgrp);
-extern void bgp_adj_out_set_subgroup(struct bgp_dest *dest,
+extern bool bgp_adj_out_set_subgroup(struct bgp_dest *dest,
struct update_subgroup *subgrp,
struct attr *attr,
struct bgp_path_info *path);
diff --git a/bgpd/bgp_updgrp_adv.c b/bgpd/bgp_updgrp_adv.c
index af8ef751da..301a8b267e 100644
--- a/bgpd/bgp_updgrp_adv.c
+++ b/bgpd/bgp_updgrp_adv.c
@@ -454,7 +454,7 @@ bgp_advertise_clean_subgroup(struct update_subgroup *subgrp,
return next;
}

-void bgp_adj_out_set_subgroup(struct bgp_dest *dest,
+bool bgp_adj_out_set_subgroup(struct bgp_dest *dest,
struct update_subgroup *subgrp, struct attr *attr,
struct bgp_path_info *path)
{
@@ -474,7 +474,7 @@ void bgp_adj_out_set_subgroup(struct bgp_dest *dest,
bgp = SUBGRP_INST(subgrp);

if (DISABLE_BGP_ANNOUNCE)
- return;
+ return false;

/* Look for adjacency information. */
adj = adj_lookup(
@@ -490,7 +490,7 @@ void bgp_adj_out_set_subgroup(struct bgp_dest *dest,
bgp_addpath_id_for_peer(peer, afi, safi,
&path->tx_addpath));
if (!adj)
- return;
+ return false;

subgrp->pscount++;
}
@@ -529,7 +529,7 @@ void bgp_adj_out_set_subgroup(struct bgp_dest *dest,
* will never be able to coalesce the 3rd peer down
*/
subgrp->version = MAX(subgrp->version, dest->version);
- return;
+ return false;
}

if (adj->adv)
@@ -576,6 +576,8 @@ void bgp_adj_out_set_subgroup(struct bgp_dest *dest,
bgp_adv_fifo_add_tail(&subgrp->sync->update, adv);

subgrp->version = MAX(subgrp->version, dest->version);
+
+ return true;
}

/* The only time 'withdraw' will be false is if we are sending
@@ -668,7 +670,7 @@ void subgroup_announce_table(struct update_subgroup *subgrp,
{
struct bgp_dest *dest;
struct bgp_path_info *ri;
- struct attr attr;
+ struct attr attr = {0};
struct peer *peer;
afi_t afi;
safi_t safi;
@@ -715,19 +717,24 @@ void subgroup_announce_table(struct update_subgroup *subgrp,
&attr, NULL)) {
/* Check if route can be advertised */
if (advertise) {
- if (!bgp_check_withdrawal(bgp, dest))
- bgp_adj_out_set_subgroup(
- dest, subgrp, &attr,
- ri);
- else
+ if (!bgp_check_withdrawal(bgp, dest)) {
+ if (!bgp_adj_out_set_subgroup(
+ dest, subgrp, &attr,
+ ri))
+ bgp_attr_flush(&attr);
+ } else {
+ bgp_attr_flush(&attr);
bgp_adj_out_unset_subgroup(
dest, subgrp, 1,
bgp_addpath_id_for_peer(
peer, afi,
safi_rib,
&ri->tx_addpath));
- }
+ }
+ } else
+ bgp_attr_flush(&attr);
} else {
+ bgp_attr_flush(&attr);
/* If default originate is enabled for
* the peer, do not send explicit
* withdraw. This will prevent deletion
@@ -947,18 +954,18 @@ void subgroup_default_originate(struct update_subgroup *subgrp, int withdraw)
if (dest) {
for (pi = bgp_dest_get_bgp_path_info(dest); pi;
pi = pi->next) {
- if (CHECK_FLAG(pi->flags, BGP_PATH_SELECTED))
- if (subgroup_announce_check(
- dest, pi, subgrp,
- bgp_dest_get_prefix(dest),
- &attr, NULL)) {
- struct attr *default_attr =
- bgp_attr_intern(&attr);
-
- bgp_adj_out_set_subgroup(
- dest, subgrp,
- default_attr, pi);
- }
+ if (!CHECK_FLAG(pi->flags, BGP_PATH_SELECTED))
+ continue;
+
+ if (subgroup_announce_check(
+ dest, pi, subgrp,
+ bgp_dest_get_prefix(dest), &attr,
+ NULL)) {
+ if (!bgp_adj_out_set_subgroup(
+ dest, subgrp, &attr, pi))
+ bgp_attr_flush(&attr);
+ } else
+ bgp_attr_flush(&attr);
}
bgp_dest_unlock_node(dest);
}
--
2.14.1


From 761907075520aa3fae70a8d18fa717a24d3cbd65 Mon Sep 17 00:00:00 2001
From: Donald Sharp <sharpd@nvidia.com>
Date: Wed, 13 Mar 2024 10:26:58 -0400
Subject: [PATCH 2/2] bgpd: Ensure that the correct aspath is free'd

Currently in subgroup_default_originate the attr.aspath
is set in bgp_attr_default_set, which hashs the aspath
and creates a refcount for it. If this is a withdraw
the subgroup_announce_check and bgp_adj_out_set_subgroup
is called which will intern the attribute. This will
cause the the attr.aspath to be set to a new value
finally at the bottom of the function it intentionally
uninterns the aspath which is not the one that was
created for this function. This reduces the other
aspath's refcount by 1 and if a clear bgp * is issued
fast enough the aspath for that will be removed
and the system will crash.

Signed-off-by: Donald Sharp <sharpd@nvidia.com>
---
bgpd/bgp_updgrp_adv.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/bgpd/bgp_updgrp_adv.c b/bgpd/bgp_updgrp_adv.c
index 301a8b267e..75e377f9a1 100644
--- a/bgpd/bgp_updgrp_adv.c
+++ b/bgpd/bgp_updgrp_adv.c
@@ -817,6 +817,7 @@ void subgroup_default_originate(struct update_subgroup *subgrp, int withdraw)
struct bgp *bgp;
struct attr attr;
struct attr *new_attr = &attr;
+ struct aspath *aspath;
struct prefix p;
struct peer *from;
struct bgp_dest *dest;
@@ -854,6 +855,7 @@ void subgroup_default_originate(struct update_subgroup *subgrp, int withdraw)
/* make coverity happy */
assert(attr.aspath);

+ aspath = attr.aspath;
attr.med = 0;
attr.flag |= ATTR_FLAG_BIT(BGP_ATTR_MULTI_EXIT_DISC);

@@ -1009,7 +1011,7 @@ void subgroup_default_originate(struct update_subgroup *subgrp, int withdraw)
}
}

- aspath_unintern(&attr.aspath);
+ aspath_unintern(&aspath);
}

/*
--
2.14.1

1 change: 1 addition & 0 deletions src/sonic-frr/patch/series
Original file line number Diff line number Diff line change
Expand Up @@ -33,3 +33,4 @@ cross-compile-changes.patch
0034-fpm-Use-vrf_id-for-vrf-not-tabled_id.patch
0035-fpm-ignore-route-from-default-table.patch
0036-Add-support-of-bgp-l3vni-evpn.patch
0037-bgp-community-memory-leak-fix.patch

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