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[PATCH 4.4 07/34] tg3: Avoid NULL pointer dereference in tg3_io_error_detected()

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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Milton Miller <miltonm@us.ibm.com>


[ Upstream commit 1b0ff89852d79354e8a091c81a88df21f5aa9f0a ]

While the driver is probing the adapter, an error may occur before the
netdev structure is allocated and attached to pci_dev. In this case,
not only netdev isn't available, but the tg3 private structure is also
not available as it is just math from the NULL pointer, so dereferences
must be skipped.

The following trace is seen when the error is triggered:

  [1.402247] Unable to handle kernel paging request for data at address 0x00001a99
  [1.402410] Faulting instruction address: 0xc0000000007e33f8
  [1.402450] Oops: Kernel access of bad area, sig: 11 [#1]
  [1.402481] SMP NR_CPUS=2048 NUMA PowerNV
  [1.402513] Modules linked in:
  [1.402545] CPU: 0 PID: 651 Comm: eehd Not tainted 4.4.0-36-generic #55-Ubuntu
  [1.402591] task: c000001fe4e42a20 ti: c000001fe4e88000 task.ti: c000001fe4e88000
  [1.402742] NIP: c0000000007e33f8 LR: c0000000007e3164 CTR: c000000000595ea0
  [1.402787] REGS: c000001fe4e8b790 TRAP: 0300   Not tainted  (4.4.0-36-generic)
  [1.402832] MSR: 9000000100009033 <SF,HV,EE,ME,IR,DR,RI,LE>  CR: 28000422  XER: 20000000
  [1.403058] CFAR: c000000000008468 DAR: 0000000000001a99 DSISR: 42000000 SOFTE: 1
  GPR00: c0000000007e3164 c000001fe4e8ba10 c0000000015c5e00 0000000000000000
  GPR04: 0000000000000001 0000000000000000 0000000000000039 0000000000000299
  GPR08: 0000000000000000 0000000000000001 c000001fe4e88000 0000000000000006
  GPR12: 0000000000000000 c00000000fb40000 c0000000000e6558 c000003ca1bffd00
  GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
  GPR20: 0000000000000000 0000000000000000 0000000000000000 c000000000d52768
  GPR24: c000000000d52740 0000000000000100 c000003ca1b52000 0000000000000002
  GPR28: 0000000000000900 0000000000000000 c00000000152a0c0 c000003ca1b52000
  [1.404226] NIP [c0000000007e33f8] tg3_io_error_detected+0x308/0x340
  [1.404265] LR [c0000000007e3164] tg3_io_error_detected+0x74/0x340

This patch avoids the NULL pointer dereference by moving the access after
the netdev NULL pointer check on tg3_io_error_detected(). Also, we add a
check for netdev being NULL on tg3_io_resume() [suggested by Michael Chan].

Fixes: 0486a063b1ff ("tg3: prevent ifup/ifdown during PCI error recovery")
Fixes: dfc8f370316b ("net/tg3: Release IRQs on permanent error")
Tested-by: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
Signed-off-by: Milton Miller <miltonm@us.ibm.com>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
Acked-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/broadcom/tg3.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -18142,14 +18142,14 @@ static pci_ers_result_t tg3_io_error_det
 
 	rtnl_lock();
 
-	/* We needn't recover from permanent error */
-	if (state == pci_channel_io_frozen)
-		tp->pcierr_recovery = true;
-
 	/* We probably don't have netdev yet */
 	if (!netdev || !netif_running(netdev))
 		goto done;
 
+	/* We needn't recover from permanent error */
+	if (state == pci_channel_io_frozen)
+		tp->pcierr_recovery = true;
+
 	tg3_phy_stop(tp);
 
 	tg3_netif_stop(tp);
@@ -18246,7 +18246,7 @@ static void tg3_io_resume(struct pci_dev
 
 	rtnl_lock();
 
-	if (!netif_running(netdev))
+	if (!netdev || !netif_running(netdev))
 		goto done;
 
 	tg3_full_lock(tp, 0);

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Thread

[PATCH 4.4 00/34] 4.4.32-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-13 12:30 +0100
  [PATCH 4.4 15/34] ip6_tunnel: fix ip6_tnl_lookup Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-13 12:30 +0100
  [PATCH 4.4 04/34] tcp: fix a compile error in DBGUNDO() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-13 12:30 +0100
  [PATCH 4.4 07/34] tg3: Avoid NULL pointer dereference in tg3_io_error_detected() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-13 12:30 +0100
  [PATCH 4.4 21/34] ipv4: disable BH in set_ping_group_range() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-13 12:30 +0100
  [PATCH 4.4 32/34] drm/amdgpu: fix DP mode validation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-13 12:30 +0100
  [PATCH 4.4 10/34] net/sched: act_vlan: Push skb->data to mac_header prior calling skb_vlan_*() functions Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-13 12:30 +0100
    Re: [PATCH 4.4 10/34] net/sched: act_vlan: Push skb->data to  mac_header prior calling skb_vlan_*() functions Shmulik Ladkani <shmulik.ladkani@gmail.com> - 2016-11-14 08:10 +0100
  [PATCH 4.4 26/34] sctp: validate chunk len before actually using it Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-13 12:30 +0100
  [PATCH 4.4 03/34] tcp: fix wrong checksum calculation on MTU probing Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-13 12:30 +0100
  [PATCH 4.4 12/34] packet: call fanout_release, while UNREGISTERING a netdev Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-13 12:40 +0100
  [PATCH 4.4 11/34] net: Add netdev all_adj_list refcnt propagation to fix panic Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-13 12:40 +0100
  [PATCH 4.4 17/34] net: pktgen: remove rcu locking in pktgen_change_name() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-13 12:40 +0100
  Re: [PATCH 4.4 00/34] 4.4.32-stable review Guenter Roeck <linux@roeck-us.net> - 2016-11-13 21:50 +0100
  Re: [PATCH 4.4 00/34] 4.4.32-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-14 09:00 +0100
  Re: [PATCH 4.4 00/34] 4.4.32-stable review Shuah Khan <shuah.kh@samsung.com> - 2016-11-14 17:50 +0100

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