This is a note to let you know that I've just added the patch titled
net: rfs: fix crash in get_rps_cpus()
to the 4.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-rfs-fix-crash-in-get_rps_cpus.patch
and it can be found in the queue-4.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Wed Apr 29 11:59:49 CEST 2015
From: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Sat, 25 Apr 2015 09:35:24 -0700
Subject: net: rfs: fix crash in get_rps_cpus()
From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit a31196b07f8034eba6a3487a1ad1bb5ec5cd58a5 ]
Commit 567e4b79731c ("net: rfs: add hash collision detection") had one
mistake :
RPS_NO_CPU is no longer the marker for invalid cpu in set_rps_cpu()
and get_rps_cpu(), as @next_cpu was the result of an AND with
rps_cpu_mask
This bug showed up on a host with 72 cpus :
next_cpu was 0x7f, and the code was trying to access percpu data of an
non existent cpu.
In a follow up patch, we might get rid of compares against nr_cpu_ids,
if we init the tables with 0. This is silly to test for a very unlikely
condition that exists only shortly after table initialization, as
we got rid of rps_reset_sock_flow() and similar functions that were
writing this RPS_NO_CPU magic value at flow dismantle : When table is
old enough, it never contains this value anymore.
Fixes: 567e4b79731c ("net: rfs: add hash collision detection")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Tom Herbert <tom@xxxxxxxxxxxxxxx>
Cc: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
Documentation/networking/scaling.txt | 2 +-
net/core/dev.c | 12 ++++++------
2 files changed, 7 insertions(+), 7 deletions(-)
--- a/Documentation/networking/scaling.txt
+++ b/Documentation/networking/scaling.txt
@@ -282,7 +282,7 @@ following is true:
- The current CPU's queue head counter >= the recorded tail counter
value in rps_dev_flow[i]
-- The current CPU is unset (equal to RPS_NO_CPU)
+- The current CPU is unset (>= nr_cpu_ids)
- The current CPU is offline
After this check, the packet is sent to the (possibly updated) current
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3041,7 +3041,7 @@ static struct rps_dev_flow *
set_rps_cpu(struct net_device *dev, struct sk_buff *skb,
struct rps_dev_flow *rflow, u16 next_cpu)
{
- if (next_cpu != RPS_NO_CPU) {
+ if (next_cpu < nr_cpu_ids) {
#ifdef CONFIG_RFS_ACCEL
struct netdev_rx_queue *rxqueue;
struct rps_dev_flow_table *flow_table;
@@ -3146,7 +3146,7 @@ static int get_rps_cpu(struct net_device
* If the desired CPU (where last recvmsg was done) is
* different from current CPU (one in the rx-queue flow
* table entry), switch if one of the following holds:
- * - Current CPU is unset (equal to RPS_NO_CPU).
+ * - Current CPU is unset (>= nr_cpu_ids).
* - Current CPU is offline.
* - The current CPU's queue tail has advanced beyond the
* last packet that was enqueued using this table entry.
@@ -3154,14 +3154,14 @@ static int get_rps_cpu(struct net_device
* have been dequeued, thus preserving in order delivery.
*/
if (unlikely(tcpu != next_cpu) &&
- (tcpu == RPS_NO_CPU || !cpu_online(tcpu) ||
+ (tcpu >= nr_cpu_ids || !cpu_online(tcpu) ||
((int)(per_cpu(softnet_data, tcpu).input_queue_head -
rflow->last_qtail)) >= 0)) {
tcpu = next_cpu;
rflow = set_rps_cpu(dev, skb, rflow, next_cpu);
}
- if (tcpu != RPS_NO_CPU && cpu_online(tcpu)) {
+ if (tcpu < nr_cpu_ids && cpu_online(tcpu)) {
*rflowp = rflow;
cpu = tcpu;
goto done;
@@ -3202,14 +3202,14 @@ bool rps_may_expire_flow(struct net_devi
struct rps_dev_flow_table *flow_table;
struct rps_dev_flow *rflow;
bool expire = true;
- int cpu;
+ unsigned int cpu;
rcu_read_lock();
flow_table = rcu_dereference(rxqueue->rps_flow_table);
if (flow_table && flow_id <= flow_table->mask) {
rflow = &flow_table->flows[flow_id];
cpu = ACCESS_ONCE(rflow->cpu);
- if (rflow->filter == filter_id && cpu != RPS_NO_CPU &&
+ if (rflow->filter == filter_id && cpu < nr_cpu_ids &&
((int)(per_cpu(softnet_data, cpu).input_queue_head -
rflow->last_qtail) <
(int)(10 * flow_table->mask)))
Patches currently in stable-queue which might be from edumazet@xxxxxxxxxx are
queue-4.0/net-rfs-fix-crash-in-get_rps_cpus.patch
queue-4.0/net-fix-crash-in-build_skb.patch
queue-4.0/tcp-avoid-looping-in-tcp_send_fin.patch
queue-4.0/net-do-not-deplete-pfmemalloc-reserve.patch
queue-4.0/tcp-fix-possible-deadlock-in-tcp_send_fin.patch
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