On Fri, 9 Mar 2018, Fredrik Noring wrote: > Scatter-gather needs to be disabled when using dma_declare_coherent_memory > and HCD_LOCAL_MEM. Andrea Righi made the equivalent fix for EHCI drivers > in commit 4307a28eb01284 "USB: EHCI: fix NULL pointer dererence in HCDs > that use HCD_LOCAL_MEM". > > The following NULL pointer WARN_ON_ONCE triggered with OHCI drivers: > > ------------[ cut here ]------------ > WARNING: CPU: 0 PID: 49 at drivers/usb/core/hcd.c:1379 hcd_alloc_coherent+0x4c/0xc8 > Modules linked in: > CPU: 0 PID: 49 Comm: usb-storage Not tainted 4.15.0+ #1014 > Stack : 00000000 00000000 805a78d2 0000003a 81f5c2cc 8053d367 804d77fc 00000031 > 805a3a08 00000563 81ee9400 805a0000 00000000 10058c00 81f61b10 805c0000 > 00000000 00000000 805a0000 00d9038e 00000004 803ee818 00000006 312e3420 > 805c0000 00000000 00000073 81f61958 00000000 00000000 802eb380 804fd538 > 00000009 00000563 81ee9400 805a0000 00000002 80056148 00000000 805a0000 > ... > Call Trace: > [<578af360>] show_stack+0x74/0x104 > [<2f3702c6>] __warn+0x118/0x120 > [<ae93fc9e>] warn_slowpath_null+0x44/0x58 > [<a891a517>] hcd_alloc_coherent+0x4c/0xc8 > [<3578fa36>] usb_hcd_map_urb_for_dma+0x4d8/0x534 > [<110bc94c>] usb_hcd_submit_urb+0x82c/0x834 > [<02eb5baf>] usb_sg_wait+0x14c/0x1a0 > [<ccd09e85>] usb_stor_bulk_transfer_sglist.part.1+0xac/0x124 > [<87a5c34c>] usb_stor_bulk_srb+0x40/0x60 > [<ff1792ac>] usb_stor_Bulk_transport+0x160/0x37c > [<b9e2709c>] usb_stor_invoke_transport+0x3c/0x500 > [<004754f4>] usb_stor_control_thread+0x258/0x28c > [<22edf42e>] kthread+0x134/0x13c > [<a419ffd0>] ret_from_kernel_thread+0x14/0x1c > ---[ end trace bcdb825805eefdcc ]--- > > Signed-off-by: Fredrik Noring <noring@xxxxxxxxxx> > > diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c > --- a/drivers/usb/host/ohci-hcd.c > +++ b/drivers/usb/host/ohci-hcd.c > @@ -446,7 +446,8 @@ static int ohci_init (struct ohci_hcd *ohci) > struct usb_hcd *hcd = ohci_to_hcd(ohci); > > /* Accept arbitrarily long scatter-gather lists */ > - hcd->self.sg_tablesize = ~0; > + if (!(hcd->driver->flags & HCD_LOCAL_MEM)) > + hcd->self.sg_tablesize = ~0; > > if (distrust_firmware) > ohci->flags |= OHCI_QUIRK_HUB_POWER; Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
