| From 85bd839983778fcd0c1c043327b14a046e979b39 Mon Sep 17 00:00:00 2001 |
| From: Gu Zheng <guz.fnst@cn.fujitsu.com> |
| Date: Wed, 10 Jun 2015 11:14:43 -0700 |
| Subject: mm/memory_hotplug.c: set zone->wait_table to null after freeing it |
| |
| From: Gu Zheng <guz.fnst@cn.fujitsu.com> |
| |
| commit 85bd839983778fcd0c1c043327b14a046e979b39 upstream. |
| |
| Izumi found the following oops when hot re-adding a node: |
| |
| BUG: unable to handle kernel paging request at ffffc90008963690 |
| IP: __wake_up_bit+0x20/0x70 |
| Oops: 0000 [#1] SMP |
| CPU: 68 PID: 1237 Comm: rs:main Q:Reg Not tainted 4.1.0-rc5 #80 |
| Hardware name: FUJITSU PRIMEQUEST2800E/SB, BIOS PRIMEQUEST 2000 Series BIOS Version 1.87 04/28/2015 |
| task: ffff880838df8000 ti: ffff880017b94000 task.ti: ffff880017b94000 |
| RIP: 0010:[<ffffffff810dff80>] [<ffffffff810dff80>] __wake_up_bit+0x20/0x70 |
| RSP: 0018:ffff880017b97be8 EFLAGS: 00010246 |
| RAX: ffffc90008963690 RBX: 00000000003c0000 RCX: 000000000000a4c9 |
| RDX: 0000000000000000 RSI: ffffea101bffd500 RDI: ffffc90008963648 |
| RBP: ffff880017b97c08 R08: 0000000002000020 R09: 0000000000000000 |
| R10: 0000000000000000 R11: 0000000000000000 R12: ffff8a0797c73800 |
| R13: ffffea101bffd500 R14: 0000000000000001 R15: 00000000003c0000 |
| FS: 00007fcc7ffff700(0000) GS:ffff880874800000(0000) knlGS:0000000000000000 |
| CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 |
| CR2: ffffc90008963690 CR3: 0000000836761000 CR4: 00000000001407e0 |
| Call Trace: |
| unlock_page+0x6d/0x70 |
| generic_write_end+0x53/0xb0 |
| xfs_vm_write_end+0x29/0x80 [xfs] |
| generic_perform_write+0x10a/0x1e0 |
| xfs_file_buffered_aio_write+0x14d/0x3e0 [xfs] |
| xfs_file_write_iter+0x79/0x120 [xfs] |
| __vfs_write+0xd4/0x110 |
| vfs_write+0xac/0x1c0 |
| SyS_write+0x58/0xd0 |
| system_call_fastpath+0x12/0x76 |
| Code: 5d c3 66 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 48 83 ec 20 65 48 8b 04 25 28 00 00 00 48 89 45 f8 31 c0 48 8d 47 48 <48> 39 47 48 48 c7 45 e8 00 00 00 00 48 c7 45 f0 00 00 00 00 48 |
| RIP [<ffffffff810dff80>] __wake_up_bit+0x20/0x70 |
| RSP <ffff880017b97be8> |
| CR2: ffffc90008963690 |
| |
| Reproduce method (re-add a node):: |
| Hot-add nodeA --> remove nodeA --> hot-add nodeA (panic) |
| |
| This seems an use-after-free problem, and the root cause is |
| zone->wait_table was not set to *NULL* after free it in |
| try_offline_node. |
| |
| When hot re-add a node, we will reuse the pgdat of it, so does the zone |
| struct, and when add pages to the target zone, it will init the zone |
| first (including the wait_table) if the zone is not initialized. The |
| judgement of zone initialized is based on zone->wait_table: |
| |
| static inline bool zone_is_initialized(struct zone *zone) |
| { |
| return !!zone->wait_table; |
| } |
| |
| so if we do not set the zone->wait_table to *NULL* after free it, the |
| memory hotplug routine will skip the init of new zone when hot re-add |
| the node, and the wait_table still points to the freed memory, then we |
| will access the invalid address when trying to wake up the waiting |
| people after the i/o operation with the page is done, such as mentioned |
| above. |
| |
| Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com> |
| Reported-by: Taku Izumi <izumi.taku@jp.fujitsu.com> |
| Reviewed by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> |
| Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> |
| Cc: Tang Chen <tangchen@cn.fujitsu.com> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| mm/memory_hotplug.c | 4 +++- |
| 1 file changed, 3 insertions(+), 1 deletion(-) |
| |
| --- a/mm/memory_hotplug.c |
| +++ b/mm/memory_hotplug.c |
| @@ -1978,8 +1978,10 @@ void try_offline_node(int nid) |
| * wait_table may be allocated from boot memory, |
| * here only free if it's allocated by vmalloc. |
| */ |
| - if (is_vmalloc_addr(zone->wait_table)) |
| + if (is_vmalloc_addr(zone->wait_table)) { |
| vfree(zone->wait_table); |
| + zone->wait_table = NULL; |
| + } |
| } |
| } |
| EXPORT_SYMBOL(try_offline_node); |