From 4307a28eb0128417d9a2b9d858d2bce70ee5b383 Mon Sep 17 00:00:00 2001 From: Andrea Righi Date: Mon, 28 Jun 2010 16:56:45 +0200 Subject: [PATCH] USB: EHCI: fix NULL pointer dererence in HCDs that use HCD_LOCAL_MEM If we use the HCD_LOCAL_MEM flag and dma_declare_coherent_memory() to enforce the host controller's local memory utilization we also need to disable native scatter-gather support, otherwise hcd_alloc_coherent() in map_urb_for_dma() is called with urb->transfer_buffer == NULL, that triggers a NULL pointer dereference. We can also consider to add a WARN_ON() and return an error code to better catch this problem in the future. At the moment no driver seems to hit this bug, so I should consider this a low-priority fix. Signed-off-by: Andrea Righi Acked-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/hcd.c | 5 +++++ drivers/usb/host/ehci-hcd.c | 3 ++- 2 files changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c index 0358c05e6e8a..c5753c797735 100644 --- a/drivers/usb/core/hcd.c +++ b/drivers/usb/core/hcd.c @@ -1218,6 +1218,11 @@ static int hcd_alloc_coherent(struct usb_bus *bus, { unsigned char *vaddr; + if (*vaddr_handle == NULL) { + WARN_ON_ONCE(1); + return -EFAULT; + } + vaddr = hcd_buffer_alloc(bus, size + sizeof(vaddr), mem_flags, dma_handle); if (!vaddr) diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c index 2a19336c9824..2e704fa3cedf 100644 --- a/drivers/usb/host/ehci-hcd.c +++ b/drivers/usb/host/ehci-hcd.c @@ -629,7 +629,8 @@ static int ehci_init(struct usb_hcd *hcd) ehci->command = temp; /* Accept arbitrarily long scatter-gather lists */ - hcd->self.sg_tablesize = ~0; + if (!(hcd->driver->flags & HCD_LOCAL_MEM)) + hcd->self.sg_tablesize = ~0; return 0; } -- 2.20.1