| Message ID | 1465483000-26759-1-git-send-email-kamal@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/drivers/misc/cxl/fault.c b/drivers/misc/cxl/fault.c index 25a5418..e4080ce 100644 --- a/drivers/misc/cxl/fault.c +++ b/drivers/misc/cxl/fault.c @@ -152,7 +152,7 @@ static void cxl_handle_page_fault(struct cxl_context *ctx, access = _PAGE_PRESENT; if (dsisr & CXL_PSL_DSISR_An_S) access |= _PAGE_RW; - if ((!ctx->kernel) || ~(dar & (1ULL << 63))) + if ((!ctx->kernel) || (REGION_ID(dar) == USER_REGION_ID)) access |= _PAGE_USER; if (dsisr & DSISR_NOHPTE)
This is a note to let you know that I have just added a patch titled cxl: Fix DAR check & use REGION_ID instead of opencoding to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree which can be found at: https://git.launchpad.net/~canonical-kernel/linux/+git/linux-stable-ckt/log/?h=linux-4.2.y-queue This patch is scheduled to be released in version 4.2.8-ckt12. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 4.2.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From 192d823774d27982bb255cd4a300d7f339fc5ae7 Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Date: Wed, 20 Apr 2016 03:59:47 -0400 Subject: cxl: Fix DAR check & use REGION_ID instead of opencoding commit 3b1dbfa14f97188ec33fdfc7acb66bea59a3bb21 upstream. The current code will set _PAGE_USER to the access flags for any fault address, because the ~ operation will be true for all address we take a fault on. But setting _PAGE_USER also means that the fault will be handled only if the page table have _PAGE_USER set. Hence there is no security hole with the current code. Now if it is an user space access, then the change in this patch really don't have an impact because we have (!ctx->kernel) set true and we take the if condition true. Now kernel context created fault on an address in the kernel range will result in a fault loop because we will not insert the hash pte due to access and pte permission mismatch. This patch fix the above issue. Fixes: f204e0b8cedd ("cxl: Driver code for powernv PCIe based cards for userspace access") Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> Acked-by: Ian Munsie <imunsie@au1.ibm.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/misc/cxl/fault.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) -- 2.7.4