From: Eric Dumazet <edumazet@xxxxxxxxxx>
commit ac888d58869bb99753e7652be19a151df9ecb35d upstream.
dst_entries_add() uses per-cpu data that might be freed at netns
dismantle from ip6_route_net_exit() calling dst_entries_destroy()
Before ip6_route_net_exit() can be called, we release all
the dsts associated with this netns, via calls to dst_release(),
which waits an rcu grace period before calling dst_destroy()
dst_entries_add() use in dst_destroy() is racy, because
dst_entries_destroy() could have been called already.
Decrementing the number of dsts must happen sooner.
Notes:
1) in CONFIG_XFRM case, dst_destroy() can call
dst_release_immediate(child), this might also cause UAF
if the child does not have DST_NOCOUNT set.
IPSEC maintainers might take a look and see how to address this.
2) There is also discussion about removing this count of dst,
which might happen in future kernels.
Fixes: f88649721268 ("ipv4: fix dst race in sk_dst_get()")
Closes: https://lore.kernel.org/lkml/CANn89iLCCGsP7SFn9HKpvnKu96Td4KD08xf7aGtiYgZnkjaL=w@xxxxxxxxxxxxxx/T/
Reported-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>
Tested-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>
Tested-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Xin Long <lucien.xin@xxxxxxxxx>
Cc: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Reviewed-by: Xin Long <lucien.xin@xxxxxxxxx>
Link: https://patch.msgid.link/20241008143110.1064899-1-edumazet@xxxxxxxxxx
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
[Conflict due to
bc9d3a9f2afc ("net: dst: Switch to rcuref_t reference counting")
is not in the tree]
Signed-off-by: Abdelkareem Abdelsaamad <kareemem@xxxxxxxxxx>
---
net/core/dst.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/net/core/dst.c b/net/core/dst.c
index 453ec8aafc4a..5bb143857336 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -109,9 +109,6 @@ struct dst_entry *dst_destroy(struct dst_entry * dst)
child = xdst->child;
}
#endif
- if (!(dst->flags & DST_NOCOUNT))
- dst_entries_add(dst->ops, -1);
-
if (dst->ops->destroy)
dst->ops->destroy(dst);
if (dst->dev)
@@ -162,6 +159,12 @@ void dst_dev_put(struct dst_entry *dst)
}
EXPORT_SYMBOL(dst_dev_put);
+static void dst_count_dec(struct dst_entry *dst)
+{
+ if (!(dst->flags & DST_NOCOUNT))
+ dst_entries_add(dst->ops, -1);
+}
+
void dst_release(struct dst_entry *dst)
{
if (dst) {
@@ -171,8 +174,10 @@ void dst_release(struct dst_entry *dst)
if (WARN_ONCE(newrefcnt < 0, "dst_release underflow"))
net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
__func__, dst, newrefcnt);
- if (!newrefcnt)
+ if (!newrefcnt){
+ dst_count_dec(dst);
call_rcu(&dst->rcu_head, dst_destroy_rcu);
+ }
}
}
EXPORT_SYMBOL(dst_release);
@@ -186,8 +191,10 @@ void dst_release_immediate(struct dst_entry *dst)
if (WARN_ONCE(newrefcnt < 0, "dst_release_immediate underflow"))
net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
__func__, dst, newrefcnt);
- if (!newrefcnt)
+ if (!newrefcnt){
+ dst_count_dec(dst);
dst_destroy(dst);
+ }
}
}
EXPORT_SYMBOL(dst_release_immediate);
--
2.40.1
