On Monday, January 20, 2014 7:26 PM Dan Williams <dan.j.williams@xxxxxxxxx> wrote: > On Mon, Jan 20, 2014 at 8:54 AM, Lukasz Dorau <lukasz.dorau@xxxxxxxxx> wrote: > > In the first place, the loop 'for' in the macro 'for_each_isci_host' > > (drivers/scsi/isci/host.h:314) is incorrect, because it accesses > > the 3rd element of 2 element array. After the 2nd iteration it executes > > the instruction: > > ihost = to_pci_info(pdev)->hosts[2] > > (while the size of the 'hosts' array equals 2) and reads an > > out of range element. > > > > In the second place, because of the following GCC v4.8 bug: > > http://marc.info/?l=linux-kernel&m=138998871911336&w=2 > > this loop is incorrectly compiled by GCC v4.8. > > As a result, on platforms with two SCU controllers, > > the loop at drivers/scsi/isci/init.c:717 is executed > > more times than it can be (for i=0,1 and 2). > > It causes the following oops after 'rmmod isci': > > > > Surprised those bugs lasted this long... some comments below. > > > BUG: unable to handle kernel NULL pointer dereference at (null) > > IP: [<ffffffff8131360b>] __list_add+0x1b/0xc0 > > Oops: 0000 [#1] SMP > > RIP: 0010:[<ffffffff8131360b>] [<ffffffff8131360b>] __list_add+0x1b/0xc0 > > Call Trace: > > [<ffffffff81661b84>] __mutex_lock_slowpath+0x114/0x1b0 > > [<ffffffff81661c3f>] mutex_lock+0x1f/0x30 > > [<ffffffffa03e97cb>] sas_disable_events+0x1b/0x50 [libsas] > > [<ffffffffa03e9818>] sas_unregister_ha+0x18/0x60 [libsas] > > [<ffffffffa040316e>] isci_unregister+0x1e/0x40 [isci] > > [<ffffffffa0403efd>] isci_pci_remove+0x5d/0x100 [isci] > > [<ffffffff813391cb>] pci_device_remove+0x3b/0xb0 > > [<ffffffff813fbf7f>] __device_release_driver+0x7f/0xf0 > > [<ffffffff813fc8f8>] driver_detach+0xa8/0xb0 > > [<ffffffff813fbb8b>] bus_remove_driver+0x9b/0x120 > > [<ffffffff813fcf2c>] driver_unregister+0x2c/0x50 > > [<ffffffff813381f3>] pci_unregister_driver+0x23/0x80 > > [<ffffffffa04152f8>] isci_exit+0x10/0x1e [isci] > > [<ffffffff810d199b>] SyS_delete_module+0x16b/0x2d0 > > [<ffffffff81012a21>] ? do_notify_resume+0x61/0xa0 > > [<ffffffff8166ce29>] system_call_fastpath+0x16/0x1b > > > > The loop has been corrected. > > This patch fixes the above oops. > > > > Signed-off-by: Lukasz Dorau <lukasz.dorau@xxxxxxxxx> > > Reviewed-by: Maciej Patelczyk <maciej.patelczyk@xxxxxxxxx> > > Tested-by: Lukasz Dorau <lukasz.dorau@xxxxxxxxx> > > Cc: Dan Williams <dan.j.williams@xxxxxxxxx> > > Cc: Dave Jiang <dave.jiang@xxxxxxxxx> > > Cc: <stable@xxxxxxxxxxxxxxx> > > --- > > drivers/scsi/isci/host.h | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/scsi/isci/host.h b/drivers/scsi/isci/host.h > > index 4911310..95adf31 100644 > > --- a/drivers/scsi/isci/host.h > > +++ b/drivers/scsi/isci/host.h > > @@ -311,9 +311,9 @@ static inline struct Scsi_Host *to_shost(struct isci_host > *ihost) > > } > > > > #define for_each_isci_host(id, ihost, pdev) \ > > - for (id = 0, ihost = to_pci_info(pdev)->hosts[id]; \ > > - id < ARRAY_SIZE(to_pci_info(pdev)->hosts) && ihost; \ > > - ihost = to_pci_info(pdev)->hosts[++id]) > > + for (id = 0, ihost = to_pci_info(pdev)->hosts[0]; \ > > No need to initialize ihost here since we assign and check it later. > > > + (id < ARRAY_SIZE(to_pci_info(pdev)->hosts)) && \ > > Just use SCI_MAX_CONTROLLERS here. > > > + (ihost = to_pci_info(pdev)->hosts[id]); id++) > > -- Thanks, Dan. I will submit the second version of the patch. Lukasz -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
