Commits
Dave Young committed 22ef882e6b5
x86/mm/numa: Fix kernel stack corruption in numa_init()->numa_clear_kernel_node_hotplug() I got below kernel panic during kdump test on Thinkpad T420 laptop: [ 0.000000] No NUMA configuration found [ 0.000000] Faking a node at [mem 0x0000000000000000-0x0000000037ba4fff] [ 0.000000] Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: ffffffff81d21910 ... [ 0.000000] Call Trace: [ 0.000000] [<ffffffff817c2a26>] dump_stack+0x45/0x57 [ 0.000000] [<ffffffff817bc8d2>] panic+0xd0/0x204 [ 0.000000] [<ffffffff81d21910>] ? numa_clear_kernel_node_hotplug+0xe6/0xf2 [ 0.000000] [<ffffffff8107741b>] __stack_chk_fail+0x1b/0x20 [ 0.000000] [<ffffffff81d21910>] numa_clear_kernel_node_hotplug+0xe6/0xf2 [ 0.000000] [<ffffffff81d21e5d>] numa_init+0x1a5/0x520 [ 0.000000] [<ffffffff81d222b1>] x86_numa_init+0x19/0x3d [ 0.000000] [<ffffffff81d22460>] initmem_init+0x9/0xb [ 0.000000] [<ffffffff81d0d00c>] setup_arch+0x94f/0xc82 [ 0.000000] [<ffffffff81d05120>] ? early_idt_handlers+0x120/0x120 [ 0.000000] [<ffffffff817bd0bb>] ? printk+0x55/0x6b [ 0.000000] [<ffffffff81d05120>] ? early_idt_handlers+0x120/0x120 [ 0.000000] [<ffffffff81d05d9b>] start_kernel+0xe8/0x4d6 [ 0.000000] [<ffffffff81d05120>] ? early_idt_handlers+0x120/0x120 [ 0.000000] [<ffffffff81d05120>] ? early_idt_handlers+0x120/0x120 [ 0.000000] [<ffffffff81d055ee>] x86_64_start_reservations+0x2a/0x2c [ 0.000000] [<ffffffff81d05751>] x86_64_start_kernel+0x161/0x184 [ 0.000000] ---[ end Kernel panic - not syncing: stack-protector: Kernel sta This is caused by writing over the end of numa mask bitmap in numa_clear_kernel_node(). numa_clear_kernel_node() tries to set the node id in a mask bitmap, by iterating all reserved regions and assuming that every region has a valid nid. This assumption is not true because there's an exception for some graphic memory quirks. See trim_snb_memory() in arch/x86/kernel/setup.c It is easily to reproduce the bug in the kdump kernel because kdump kernel use pre-reserved memory instead of the whole memory, but kexec pass other reserved memory ranges to 2nd kernel as well. like below in my test: kdump kernel ram 0x2d000000 - 0x37bfffff One of the reserved regions: 0x40000000 - 0x40100000 which includes 0x40004000, a page excluded in trim_snb_memory(). For this memblock reserved region the nid is not set, it is still default value MAX_NUMNODES. later node_set will set bit MAX_NUMNODES thus stack corruption happen. This also happens when booting with mem= kernel commandline during my test. Fixing it by adding a check, do not call node_set in case nid is MAX_NUMNODES. Signed-off-by: Dave Young <dyoung@redhat.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Borislav Petkov <bp@alien8.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: bhe@redhat.com Cc: qiuxishi@huawei.com Link: http://lkml.kernel.org/r/20150407134132.GA23522@dhcp-16-198.nay.redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>