• Dave Young's avatar
    x86/mm/numa: Fix kernel stack corruption in numa_init()->numa_clear_kernel_node_hotplug() · 22ef882e
    Dave Young authored
    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: default avatarDave Young <dyoung@redhat.com>
    Reviewed-by: default avatarYasuaki 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.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    22ef882e
numa.c 21.7 KB