• Munehisa Kamata's avatar
    xen-blkfront: use a right index when checking requests · 33f1d0c7
    Munehisa Kamata authored
    commit b15bd8cb upstream.
    
    Since commit d05d7f40 ("Merge branch 'for-4.8/core' of
    git://git.kernel.dk/linux-block") and 3fc9d690 ("Merge branch
    'for-4.8/drivers' of git://git.kernel.dk/linux-block"), blkfront_resume()
    has been using an index for iterating ring_info to check request when
    iterating blk_shadow in an inner loop. This seems to have been
    accidentally introduced during the massive rewrite of the block layer
    macros in the commits.
    
    This may cause crash like this:
    
    [11798.057074] BUG: unable to handle kernel NULL pointer dereference at 0000000000000048
    [11798.058832] IP: [<ffffffff814411fa>] blkfront_resume+0x10a/0x610
    ....
    [11798.061063] Call Trace:
    [11798.061063]  [<ffffffff8139ce93>] xenbus_dev_resume+0x53/0x140
    [11798.061063]  [<ffffffff8139ce40>] ? xenbus_dev_probe+0x150/0x150
    [11798.061063]  [<ffffffff813f359e>] dpm_run_callback+0x3e/0x110
    [11798.061063]  [<ffffffff813f3a08>] device_resume+0x88/0x190
    [11798.061063]  [<ffffffff813f4cc0>] dpm_resume+0x100/0x2d0
    [11798.061063]  [<ffffffff813f5221>] dpm_resume_end+0x11/0x20
    [11798.061063]  [<ffffffff813950a8>] do_suspend+0xe8/0x1a0
    [11798.061063]  [<ffffffff813954bd>] shutdown_handler+0xfd/0x130
    [11798.061063]  [<ffffffff8139aba0>] ? split+0x110/0x110
    [11798.061063]  [<ffffffff8139ac26>] xenwatch_thread+0x86/0x120
    [11798.061063]  [<ffffffff810b4570>] ? prepare_to_wait_event+0x110/0x110
    [11798.061063]  [<ffffffff8108fe57>] kthread+0xd7/0xf0
    [11798.061063]  [<ffffffff811da811>] ? kfree+0x121/0x170
    [11798.061063]  [<ffffffff8108fd80>] ? kthread_park+0x60/0x60
    [11798.061063]  [<ffffffff810863b0>] ?  call_usermodehelper_exec_work+0xb0/0xb0
    [11798.061063]  [<ffffffff810864ea>] ?  call_usermodehelper_exec_async+0x13a/0x140
    [11798.061063]  [<ffffffff81534a45>] ret_from_fork+0x25/0x30
    
    Use the right index in the inner loop.
    
    Fixes: d05d7f40 ("Merge branch 'for-4.8/core' of git://git.kernel.dk/linux-block")
    Fixes: 3fc9d690 ("Merge branch 'for-4.8/drivers' of git://git.kernel.dk/linux-block")
    Signed-off-by: default avatarMunehisa Kamata <kamatam@amazon.com>
    Reviewed-by: default avatarThomas Friebel <friebelt@amazon.de>
    Reviewed-by: default avatarEduardo Valentin <eduval@amazon.com>
    Reviewed-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
    Cc: Juergen Gross <jgross@suse.com>
    Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    Reviewed-by: default avatarRoger Pau Monne <roger.pau@citrix.com>
    Cc: xen-devel@lists.xenproject.org
    Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    33f1d0c7
xen-blkfront.c 72.7 KB