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zebra: Fix leaked nhe

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During route processing in zebra, Zebra will create a nexthop
group that matches the nexthops passed down from the routing
protocol.  Then Zebra will look to see if it can re-use a
nhe from a previous version of the route entry( say a interface
goes down ).  If Zebra decides to re-use an nhe it was just dropping
the route entry created.  Which led to nexthop group's that had
a refcount of 0 and in some cases these nexthop groups were installed
into the kernel.

Add a bit of code to see if the returned entry is not being used
and it has no reference count and if so, properly dispose of it.

Signed-off-by: Donald Sharp <sharpd@nvidia.com>
This commit is contained in:
Donald Sharp 2025-01-09 12:34:50 -05:00
parent 465d286819
commit 97fa24e70b
1 changed files with 14 additions and 5 deletions
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19
zebra/zebra_nhg.c
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@ -3089,7 +3089,7 @@ static struct nhg_hash_entry *zebra_nhg_rib_compare_old_nhe(
int nexthop_active_update(struct route_node *rn, struct route_entry *re,
struct route_entry *old_re)
{
struct nhg_hash_entry *curr_nhe;
struct nhg_hash_entry *curr_nhe, *remove;
uint32_t curr_active = 0, backup_active = 0;
if (PROTO_OWNED(re->nhe))
@ -3143,16 +3143,25 @@ backups_done:
new_nhe = zebra_nhg_rib_find_nhe(curr_nhe, rt_afi);
remove = new_nhe;
if (old_re && old_re->type == re->type &&
old_re->instance == re->instance)
new_nhe = zebra_nhg_rib_compare_old_nhe(rn, re, new_nhe,
old_re->nhe);
if (IS_ZEBRA_DEBUG_NHG_DETAIL)
zlog_debug(
"%s: re %p CHANGED: nhe %p (%pNG) => new_nhe %p (%pNG)",
__func__, re, re->nhe, re->nhe, new_nhe,
new_nhe);
zlog_debug("%s: re %p CHANGED: nhe %p (%pNG) => new_nhe %p (%pNG) rib_find_nhe returned %p (%pNG) refcnt: %d",
__func__, re, re->nhe, re->nhe, new_nhe, new_nhe, remove, remove,
remove ? remove->refcnt : 0);
/*
* if the results from zebra_nhg_rib_find_nhe is being
* dropped and it was generated in that function
* (refcnt of 0) then we know we can clean it up
*/
if (remove && remove != new_nhe && remove != re->nhe && remove->refcnt == 0)
zebra_nhg_handle_uninstall(remove);
route_entry_update_nhe(re, new_nhe);
}