From: Jesper Dangaard Brouer <brouer@redhat.com>
To: unlisted-recipients:; (no To-header on input)
Cc: "Toke Høiland-Jørgensen" <toke@redhat.com>,
netdev@vger.kernel.org,
"Ilias Apalodimas" <ilias.apalodimas@linaro.org>,
"Jesper Dangaard Brouer" <brouer@redhat.com>,
"Saeed Mahameed" <saeedm@mellanox.com>,
"Matteo Croce" <mcroce@redhat.com>,
"Jonathan Lemon" <jonathan.lemon@gmail.com>,
"Lorenzo Bianconi" <lorenzo@kernel.org>,
"Tariq Toukan" <tariqt@mellanox.com>
Subject: [net-next v2 PATCH 1/3] xdp: remove memory poison on free for struct xdp_mem_allocator
Date: Sat, 16 Nov 2019 12:22:38 +0100 [thread overview]
Message-ID: <157390335803.4062.9077462420905595048.stgit@firesoul> (raw)
In-Reply-To: <157390333500.4062.15569811103072483038.stgit@firesoul>
When looking at the details I realised that the memory poison in
__xdp_mem_allocator_rcu_free doesn't make sense. This is because the
SLUB allocator uses the first 16 bytes (on 64 bit), for its freelist,
which overlap with members in struct xdp_mem_allocator, that were
updated. Thus, SLUB already does the "poisoning" for us.
I still believe that poisoning memory make sense in other cases.
Kernel have gained different use-after-free detection mechanism, but
enabling those is associated with a huge overhead. Experience is that
debugging facilities can change the timing so much, that that a race
condition will not be provoked when enabled. Thus, I'm still in favour
of poisoning memory where it makes sense.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
---
net/core/xdp.c | 5 -----
1 file changed, 5 deletions(-)
diff --git a/net/core/xdp.c b/net/core/xdp.c
index 8e405abaf05a..e334fad0a6b8 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -73,11 +73,6 @@ static void __xdp_mem_allocator_rcu_free(struct rcu_head *rcu)
/* Allow this ID to be reused */
ida_simple_remove(&mem_id_pool, xa->mem.id);
- /* Poison memory */
- xa->mem.id = 0xFFFF;
- xa->mem.type = 0xF0F0;
- xa->allocator = (void *)0xDEAD9001;
-
kfree(xa);
}
next prev parent reply other threads:[~2019-11-16 11:22 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-16 11:22 [net-next v2 PATCH 0/3] page_pool: followup changes to restore tracepoint features Jesper Dangaard Brouer
2019-11-16 11:22 ` Jesper Dangaard Brouer [this message]
2019-11-16 11:22 ` [net-next v2 PATCH 2/3] page_pool: add destroy attempts counter and rename tracepoint Jesper Dangaard Brouer
2019-11-16 11:22 ` [net-next v2 PATCH 3/3] page_pool: extend tracepoint to also include the page PFN Jesper Dangaard Brouer
2019-11-19 1:03 ` [net-next v2 PATCH 0/3] page_pool: followup changes to restore tracepoint features David Miller
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