• Michael S. Tsirkin's avatar
    virtio: fix out of range array access · 31198159
    Michael S. Tsirkin authored
    I have observed the following error on virtio-net module unload:
    
    ------------[ cut here ]------------
    WARNING: at kernel/irq/manage.c:858 __free_irq+0xa0/0x14c()
    Hardware name: Bochs
    Trying to free already-free IRQ 0
    Modules linked in: virtio_net(-) virtio_blk virtio_pci virtio_ring
    virtio af_packet e1000 shpchp aacraid uhci_hcd ohci_hcd ehci_hcd [last
    unloaded: scsi_wait_scan]
    Pid: 1957, comm: rmmod Not tainted 2.6.33-rc8-vhost #24
    Call Trace:
     [<ffffffff8103e195>] warn_slowpath_common+0x7c/0x94
     [<ffffffff8103e204>] warn_slowpath_fmt+0x41/0x43
     [<ffffffff810a7a36>] ? __free_pages+0x5a/0x70
     [<ffffffff8107cc00>] __free_irq+0xa0/0x14c
     [<ffffffff8107cceb>] free_irq+0x3f/0x65
     [<ffffffffa0081424>] vp_del_vqs+0x81/0xb1 [virtio_pci]
     [<ffffffffa0091d29>] virtnet_remove+0xda/0x10b [virtio_net]
     [<ffffffffa0075200>] virtio_dev_remove+0x22/0x4a [virtio]
     [<ffffffff812709ee>] __device_release_driver+0x66/0xac
     [<ffffffff81270ab7>] driver_detach+0x83/0xa9
     [<ffffffff8126fc66>] bus_remove_driver+0x91/0xb4
     [<ffffffff81270fcf>] driver_unregister+0x6c/0x74
     [<ffffffffa0075418>] unregister_virtio_driver+0xe/0x10 [virtio]
     [<ffffffffa0091c4d>] fini+0x15/0x17 [virtio_net]
     [<ffffffff8106997b>] sys_delete_module+0x1c3/0x230
     [<ffffffff81007465>] ? old_ich_force_enable_hpet+0x117/0x164
     [<ffffffff813bb720>] ? do_page_fault+0x29c/0x2cc
     [<ffffffff81028e58>] sysenter_dispatch+0x7/0x27
    ---[ end trace 15e88e4c576cc62b ]---
    
    The bug is in virtio-pci: we use msix_vector as array index to get irq
    entry, but some vqs do not have a dedicated vector so this causes an out
    of bounds access.  By chance, we seem to often get 0 value, which
    results in this error.
    
    Fix by verifying that vector is legal before using it as index.
    Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
    Acked-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
    Acked-by: default avatarShirley Ma <xma@us.ibm.com>
    Acked-by: default avatarAmit Shah <amit.shah@redhat.com>
    31198159
virtio_pci.c 19.5 KB