netdev - [PATCH] rps: Handle double list_add at __napi

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 15 Jun 2015 21:46:38 -0000
From:	subashab@...eaurora.org
To:	netdev@...r.kernel.org
Cc:	eric.dumazet@...il.com
Subject: [PATCH] rps: Handle double list_add at __napi_schedule

When NAPI_STATE_SCHED state is not set, enqueue_to_backlog()
will queue an IPI and add the backlog queue to the poll list. A packet
added by RPS onto the core could also add the NAPI backlog struct to the
poll list. This double addition to the list causes a crash -

2920.540304:   <2> list_add double add: new=ffffffc076ed2930,
prev=ffffffc076ed2930, next=ffffffc076ed2850.
   [<ffffffc000460dd4>] __list_add+0xcc/0xf0
2921.064962:   <2> [<ffffffc000b44880>] rps_trigger_softirq+0x1c/0x40
2921.070779:   <2> [<ffffffc000284a14>]
generic_smp_call_function_single_interrupt+0xe8/0x12c
2921.078678:   <2> [<ffffffc00020d9ac>] handle_IPI+0x8c/0x1ec
2921.083796:   <2> [<ffffffc000200714>] gic_handle_irq+0x94/0xb0

Fix this race for double addition to list by checking the NAPI state.

Acked-by: Sharat Masetty <smasetty@....qualcomm.com>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@...eaurora.org>

diff --git a/net/core/dev.c b/net/core/dev.c
index 6f561de..57d6d39 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3225,7 +3225,8 @@ static void rps_trigger_softirq(void *data)
 {
        struct softnet_data *sd = data;

-       ____napi_schedule(sd, &sd->backlog);
+       if (!test_bit(NAPI_STATE_SCHED, &sd->backlog.state))
+               ____napi_schedule(sd, &sd->backlog);
        sd->received_rps++;
 }


--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html