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The mesh_path_reclaim() function, called from an rcu callback, cancels the mesh_path_timer associated with a mesh path. Unfortunately, this call can happen much later, perhaps after the hash table itself is destroyed. Such a situation led to the following crash in mesh_path_send_to_gates() when dereferencing the tbl pointer: [ 23.901661] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 [ 23.905516] IP: [<ffffffff814c910b>] mesh_path_send_to_gates+0x2b/0x740 [ 23.908757] PGD 99ca067 PUD 99c4067 PMD 0 [ 23.910789] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC [ 23.913485] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.5.0-rc6-wt+ #43 [ 23.916675] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014 [ 23.920471] task: ffffffff81685500 ti: ffffffff81678000 task.ti: ffffffff81678000 [ 23.922619] RIP: 0010:[<ffffffff814c910b>] [<ffffffff814c910b>] mesh_path_send_to_gates+0x2b/0x740 [ 23.925237] RSP: 0018:ffff88000b403d30 EFLAGS: 00010286 [ 23.926739] RAX: 0000000000000000 RBX: ffff880009bc0d20 RCX: 0000000000000102 [ 23.928796] RDX: 000000000000002e RSI: 0000000000000001 RDI: ffff880009bc0d20 [ 23.930895] RBP: ffff88000b403e18 R08: 0000000000000001 R09: 0000000000000001 [ 23.932917] R10: 0000000000000000 R11: 0000000000000001 R12: ffff880009c20940 [ 23.936370] R13: ffff880009bc0e70 R14: ffff880009c21c40 R15: ffff880009bc0d20 [ 23.939823] FS: 0000000000000000(0000) GS:ffff88000b400000(0000) knlGS:0000000000000000 [ 23.943688] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 23.946429] CR2: 0000000000000008 CR3: 00000000099c5000 CR4: 00000000000006b0 [ 23.949861] Stack: [ 23.950840] 000000000000002e ffff880009c20940 ffff88000b403da8 ffffffff8109e551 [ 23.954467] ffffffff82711be2 000000000000002e 0000000000000000 ffffffff8166a5f5 [ 23.958141] 0000000000685ce8 0000000000000246 ffff880009bc0d20 ffff880009c20940 [ 23.961801] Call Trace: [ 23.962987] <IRQ> [ 23.963963] [<ffffffff8109e551>] ? vprintk_emit+0x351/0x5e0 [ 23.966782] [<ffffffff8109e8ff>] ? vprintk_default+0x1f/0x30 [ 23.969529] [<ffffffff810ffa41>] ? printk+0x48/0x50 [ 23.971956] [<ffffffff814ceef3>] mesh_path_timer+0x133/0x160 [ 23.974707] [<ffffffff814cedc0>] ? mesh_nexthop_resolve+0x230/0x230 [ 23.977775] [<ffffffff810b04ee>] call_timer_fn+0xce/0x330 [ 23.980448] [<ffffffff810b0425>] ? call_timer_fn+0x5/0x330 [ 23.983126] [<ffffffff814cedc0>] ? mesh_nexthop_resolve+0x230/0x230 [ 23.986091] [<ffffffff810b097c>] run_timer_softirq+0x22c/0x390 Instead of cancelling in the RCU callback, set a new flag to prevent the timer from being rearmed, and then cancel the timer synchronously when freeing the mesh path. This leaves mesh_path_reclaim() doing nothing but kfree, so switch to kfree_rcu(). Fixes: 3b302ada7f0a ("mac80211: mesh: move path tables into if_mesh") Signed-off-by: Bob Copeland <me@bobcopeland.com> Signed-off-by: Johannes Berg <johannes.berg@intel.com> |
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.. | ||
aes_ccm.c | ||
aes_ccm.h | ||
aes_cmac.c | ||
aes_cmac.h | ||
aes_gcm.c | ||
aes_gcm.h | ||
aes_gmac.c | ||
aes_gmac.h | ||
agg-rx.c | ||
agg-tx.c | ||
cfg.c | ||
chan.c | ||
debug.h | ||
debugfs_key.c | ||
debugfs_key.h | ||
debugfs_netdev.c | ||
debugfs_netdev.h | ||
debugfs_sta.c | ||
debugfs_sta.h | ||
debugfs.c | ||
debugfs.h | ||
driver-ops.c | ||
driver-ops.h | ||
ethtool.c | ||
ht.c | ||
ibss.c | ||
ieee80211_i.h | ||
iface.c | ||
Kconfig | ||
key.c | ||
key.h | ||
led.c | ||
led.h | ||
main.c | ||
Makefile | ||
mesh_hwmp.c | ||
mesh_pathtbl.c | ||
mesh_plink.c | ||
mesh_ps.c | ||
mesh_sync.c | ||
mesh.c | ||
mesh.h | ||
michael.c | ||
michael.h | ||
mlme.c | ||
ocb.c | ||
offchannel.c | ||
pm.c | ||
rate.c | ||
rate.h | ||
rc80211_minstrel_debugfs.c | ||
rc80211_minstrel_ht_debugfs.c | ||
rc80211_minstrel_ht.c | ||
rc80211_minstrel_ht.h | ||
rc80211_minstrel.c | ||
rc80211_minstrel.h | ||
rx.c | ||
scan.c | ||
spectmgmt.c | ||
sta_info.c | ||
sta_info.h | ||
status.c | ||
tdls.c | ||
tkip.c | ||
tkip.h | ||
trace_msg.h | ||
trace.c | ||
trace.h | ||
tx.c | ||
util.c | ||
vht.c | ||
wep.c | ||
wep.h | ||
wme.c | ||
wme.h | ||
wpa.c | ||
wpa.h |