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linux/net/ax25
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Jarek Poplawski 215f7b08f2 [AX25]: Locking dependencies fix in ax25_disconnect(). 
Bernard Pidoux reported these lockdep warnings:

[ INFO: possible irq lock inversion dependency detected ]
2.6.23.1 #1
---------------------------------------------------------
fpac/4933 just changed the state of lock:
 (slock-AF_AX25){--..}, at: [<d8be3312>] ax25_disconnect+0x46/0xaf
 [ax25]
 but this lock was taken by another, soft-irq-safe lock in the past:
  (ax25_list_lock){-+..}

  and interrupts could create inverse lock ordering between them.
  [...]

[ INFO: inconsistent lock state ]
2.6.23.1 #1
---------------------------------
inconsistent {in-softirq-W} -> {softirq-on-W} usage.
ax25_call/4005 [HC0[0]:SC0[0]:HE1:SE1] takes:
 (slock-AF_AX25){-+..}, at: [<d8b79312>] ax25_disconnect+0x46/0xaf [ax25]
 [...]

This means slock-AF_AX25 could be taken both from softirq and process
context with softirqs enabled, so it's endangered itself, but also makes
ax25_list_lock vulnerable. It was not 100% verified if the real lockup
can happen, but this fix isn't very costly and looks safe anyway.
(It was tested by Bernard with 2.6.23.9 and 2.6.24-rc5 kernels.)


Reported_by: Bernard Pidoux <pidoux@ccr.jussieu.fr>
Tested_by: Bernard Pidoux <pidoux@ccr.jussieu.fr>
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-12-16 14:02:07 -08:00
..
af_ax25.c [NET]: Forget the zero_it argument of sk_alloc() 2007-11-01 00:39:31 -07:00
ax25_addr.c
ax25_dev.c
ax25_ds_in.c Convert files to UTF-8 and some cleanups 2007-10-19 23:21:04 +02:00
ax25_ds_subr.c Convert files to UTF-8 and some cleanups 2007-10-19 23:21:04 +02:00
ax25_ds_timer.c
ax25_iface.c [AX25]: don't free pointers to statically allocated data 2007-08-14 17:24:05 -07:00
ax25_in.c [NET]: Make packet reception network namespace safe 2007-10-10 16:49:08 -07:00
ax25_ip.c [NET]: Move hardware header operations out of netdevice. 2007-10-10 16:52:52 -07:00
ax25_out.c
ax25_route.c [NET]: Make all initialized struct seq_operations const. 2007-07-10 23:07:31 -07:00
ax25_std_in.c
ax25_std_subr.c
ax25_std_timer.c
ax25_subr.c [AX25]: Locking dependencies fix in ax25_disconnect(). 2007-12-16 14:02:07 -08:00
ax25_timer.c
ax25_uid.c [NET]: Make all initialized struct seq_operations const. 2007-07-10 23:07:31 -07:00
Kconfig [S390] Kconfig: unwanted menus for s390. 2007-05-10 15:46:07 +02:00
Makefile
sysctl_net_ax25.c
TODO