From: Vishal Verma vishal.l.verma@intel.com
mainline inclusion from mainline-v5.8-rc1 commit fa6d9ec790550b758215b6c6fa9f940878c3e2a2 category: bugfix bugzilla: 36877 CVE: NA
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A misbehaving qemu created a situation where the ACPI SRAT table advertised one fewer proximity domains than intended. The NFIT table did describe all the expected proximity domains. This caused the device dax driver to assign an impossible target_node to the device, and when hotplugged as system memory, this would fail with the following signature:
BUG: kernel NULL pointer dereference, address: 0000000000000088 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 80000001767d4067 P4D 80000001767d4067 PUD 10e0c4067 PMD 0 Oops: 0000 [#1] SMP PTI CPU: 4 PID: 22737 Comm: kswapd3 Tainted: G O 5.6.0-rc5 #9 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 RIP: 0010:prepare_kswapd_sleep+0x7c/0xc0 Code: 89 df e8 87 fd ff ff 89 c2 31 c0 84 d2 74 e6 0f 1f 44 00 00 48 8b 05 fb af 7a 01 48 63 93 88 1d 01 00 48 8b 84 d0 20 0f 00 00 <48> 3b 98 88 00 00 00 75 28 f0 80 a0 80 00 00 00 fe f0 80 a3 38 20 RSP: 0018:ffffc900017a3e78 EFLAGS: 00010202 RAX: 0000000000000000 RBX: ffff8881209e0000 RCX: 0000000000000000 RDX: 0000000000000003 RSI: 0000000000000000 RDI: ffff8881209e0e80 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000008000 R10: 0000000000000000 R11: 0000000000000003 R12: 0000000000000003 R13: 0000000000000003 R14: 0000000000000000 R15: ffffc900017a3ec8 FS: 0000000000000000(0000) GS:ffff888318c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000088 CR3: 0000000120b50002 CR4: 00000000001606e0 Call Trace: kswapd+0x103/0x520 kthread+0x120/0x140 ret_from_fork+0x3a/0x50
Add a check in the add_memory path to fail if the node to which we are adding memory is in the node_possible_map
Signed-off-by: Vishal Verma vishal.l.verma@intel.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Acked-by: David Hildenbrand david@redhat.com Acked-by: Michal Hocko mhocko@suse.com Cc: David Hildenbrand david@redhat.com Cc: Dan Williams dan.j.williams@intel.com Cc: Dave Hansen dave.hansen@linux.intel.com Link: http://lkml.kernel.org/r/20200416225438.15208-1-vishal.l.verma@intel.com Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Liu Shixin liushixin2@huawei.com Reviewed-by: Kefeng Wang wangkefeng.wang@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- mm/memory_hotplug.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 0031c5063aa1..bdafc63ab789 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1058,6 +1058,11 @@ int __ref add_memory_resource(int nid, struct resource *res, bool online) if (ret) return ret;
+ if (!node_possible(nid)) { + WARN(1, "node %d was absent from the node_possible_map\n", nid); + return -EINVAL; + } + mem_hotplug_begin();
/*