• Ken Xue's avatar
    SCSI: Fix NULL pointer dereference in runtime PM · 2bfa7bba
    Ken Xue authored
    commit 4fd41a85 upstream.
    
    The routines in scsi_pm.c assume that if a runtime-PM callback is
    invoked for a SCSI device, it can only mean that the device's driver
    has asked the block layer to handle the runtime power management (by
    calling blk_pm_runtime_init(), which among other things sets q->dev).
    
    However, this assumption turns out to be wrong for things like the ses
    driver.  Normally ses devices are not allowed to do runtime PM, but
    userspace can override this setting.  If this happens, the kernel gets
    a NULL pointer dereference when blk_post_runtime_resume() tries to use
    the uninitialized q->dev pointer.
    
    This patch fixes the problem by checking q->dev in block layer before
    handle runtime PM. Since ses doesn't define any PM callbacks and call
    blk_pm_runtime_init(), the crash won't occur.
    
    This fixes Bugzilla #101371.
    https://bugzilla.kernel.org/show_bug.cgi?id=101371
    
    More discussion can be found from below link.
    http://marc.info/?l=linux-scsi&m=144163730531875&w=2Signed-off-by: default avatarKen Xue <Ken.Xue@amd.com>
    Acked-by: default avatarAlan Stern <stern@rowland.harvard.edu>
    Cc: Xiangliang Yu <Xiangliang.Yu@amd.com>
    Cc: James E.J. Bottomley <JBottomley@odin.com>
    Cc: Jens Axboe <axboe@kernel.dk>
    Cc: Michael Terry <Michael.terry@canonical.com>
    Signed-off-by: default avatarJens Axboe <axboe@fb.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    2bfa7bba
blk-core.c 86.6 KB