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authorBob Copeland <me@bobcopeland.com>2016-03-18 22:03:24 -0400
committerJohannes Berg <johannes.berg@intel.com>2016-04-05 21:34:49 +0200
commit749329594b5e0fb612b2de642a692323ddf661dd (patch)
treeb8c360b3c7af4e979bbfacdda2f930d8fdf81438 /net/mac80211/mesh.h
parent52cfa1d6146c5aa48360b02533fc7e039a66086e (diff)
mac80211: mesh: fix crash in mesh_path_timer
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>
Diffstat (limited to 'net/mac80211/mesh.h')
-rw-r--r--net/mac80211/mesh.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/net/mac80211/mesh.h b/net/mac80211/mesh.h
index cc6854db156e..e1415c952e9c 100644
--- a/net/mac80211/mesh.h
+++ b/net/mac80211/mesh.h
@@ -32,6 +32,8 @@
* @MESH_PATH_RESOLVED: the mesh path can has been resolved
* @MESH_PATH_REQ_QUEUED: there is an unsent path request for this destination
* already queued up, waiting for the discovery process to start.
+ * @MESH_PATH_DELETED: the mesh path has been deleted and should no longer
+ * be used
*
* MESH_PATH_RESOLVED is used by the mesh path timer to
* decide when to stop or cancel the mesh path discovery.
@@ -43,6 +45,7 @@ enum mesh_path_flags {
MESH_PATH_FIXED = BIT(3),
MESH_PATH_RESOLVED = BIT(4),
MESH_PATH_REQ_QUEUED = BIT(5),
+ MESH_PATH_DELETED = BIT(6),
};
/**