From bcdb72ac7c00d2b56359fc82bcc8fe50454717d5 Mon Sep 17 00:00:00 2001 From: Imre Deak Date: Fri, 14 Feb 2014 20:23:54 +0200 Subject: [PATCH] drm/i915: fix pch pci device enumeration pci_get_class(class, from) drops the refcount for 'from', so the extra pci_dev_put we do on it will result in a use after free bug starting with the WARN below. Regression introduced in commit 6a9c4b35e6696a63805b6da5e4889c6986e9ee1b Author: Rui Guo Date: Wed Jun 19 21:10:23 2013 +0800 drm/i915: Fix PCH detect with multiple ISA bridges in VM [ 164.338460] WARNING: CPU: 1 PID: 2094 at include/linux/kref.h:47 klist_next+0xae/0x110() [ 164.347731] CPU: 1 PID: 2094 Comm: modprobe Tainted: G O 3.13.0-imre+ #354 [ 164.356468] Hardware name: Intel Corp. VALLEYVIEW B0 PLATFORM/NOTEBOOK, BIOS BYTICRB1.X64.0062.R70.1310112051 10/11/2013 [ 164.368796] Call Trace: [ 164.371609] [] dump_stack+0x4e/0x7a [ 164.377447] [] warn_slowpath_common+0x7d/0xa0 [ 164.384238] [] warn_slowpath_null+0x1a/0x20 [ 164.390851] [] klist_next+0xae/0x110 [ 164.396777] [] ? pci_do_find_bus+0x70/0x70 [ 164.403286] [] bus_find_device+0x89/0xc0 [ 164.409719] [] pci_get_dev_by_id+0x63/0xa0 [ 164.416238] [] pci_get_class+0x44/0x50 [ 164.422433] [] intel_dsm_detect+0x16f/0x1f0 [i915] [ 164.429801] [] intel_register_dsm_handler+0xe/0x10 [i915] [ 164.437831] [] i915_driver_load+0xafe/0xf30 [i915] [ 164.445126] [] ? intel_alloc_coherent+0x110/0x110 [ 164.452340] [] drm_dev_register+0xc7/0x150 [drm] [ 164.459462] [] drm_get_pci_dev+0x11f/0x1f0 [drm] [ 164.466554] [] ? _raw_spin_unlock_irqrestore+0x51/0x70 [ 164.474287] [] i915_pci_probe+0x56/0x60 [i915] [ 164.481185] [] pci_device_probe+0x78/0xf0 [ 164.487603] [] driver_probe_device+0x155/0x350 [ 164.494505] [] __driver_attach+0x6e/0xa0 [ 164.500826] [] ? __device_attach+0x50/0x50 [ 164.507333] [] bus_for_each_dev+0x6e/0xc0 [ 164.513752] [] driver_attach+0x1e/0x20 [ 164.519870] [] bus_add_driver+0x138/0x260 [ 164.526289] [] ? 0xffffffffa0187fff [ 164.532116] [] driver_register+0x98/0xe0 [ 164.538558] [] ? 0xffffffffa0187fff [ 164.544389] [] __pci_register_driver+0x60/0x70 [ 164.551336] [] drm_pci_init+0x6d/0x120 [drm] [ 164.558040] [] ? 0xffffffffa0187fff [ 164.563928] [] i915_init+0x6a/0x6c [i915] [ 164.570363] [] do_one_initcall+0xaa/0x160 [ 164.576783] [] ? set_memory_nx+0x40/0x50 [ 164.583100] [] load_module+0x1fb5/0x2550 [ 164.589410] [] ? store_uevent+0x40/0x40 [ 164.595628] [] SyS_init_module+0xed/0x100 [ 164.602048] [] system_call_fastpath+0x16/0x1b v2: simplify the loop further (Chris) Signed-off-by: Imre Deak Cc: Jesse Barnes Reported-by: Jesse Barnes Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=65652 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=74161 Reviewed-by: Chris Wilson Cc: stable@vger.kernel.org Signed-off-by: Jani Nikula --- drivers/gpu/drm/i915/i915_drv.c | 23 +++++++++-------------- 1 file changed, 9 insertions(+), 14 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c index 04f1f02c4019..ec7bb0fc71bc 100644 --- a/drivers/gpu/drm/i915/i915_drv.c +++ b/drivers/gpu/drm/i915/i915_drv.c @@ -403,7 +403,7 @@ MODULE_DEVICE_TABLE(pci, pciidlist); void intel_detect_pch(struct drm_device *dev) { struct drm_i915_private *dev_priv = dev->dev_private; - struct pci_dev *pch; + struct pci_dev *pch = NULL; /* In all current cases, num_pipes is equivalent to the PCH_NOP setting * (which really amounts to a PCH but no South Display). @@ -424,12 +424,9 @@ void intel_detect_pch(struct drm_device *dev) * all the ISA bridge devices and check for the first match, instead * of only checking the first one. */ - pch = pci_get_class(PCI_CLASS_BRIDGE_ISA << 8, NULL); - while (pch) { - struct pci_dev *curr = pch; + while ((pch = pci_get_class(PCI_CLASS_BRIDGE_ISA << 8, pch))) { if (pch->vendor == PCI_VENDOR_ID_INTEL) { - unsigned short id; - id = pch->device & INTEL_PCH_DEVICE_ID_MASK; + unsigned short id = pch->device & INTEL_PCH_DEVICE_ID_MASK; dev_priv->pch_id = id; if (id == INTEL_PCH_IBX_DEVICE_ID_TYPE) { @@ -461,18 +458,16 @@ void intel_detect_pch(struct drm_device *dev) DRM_DEBUG_KMS("Found LynxPoint LP PCH\n"); WARN_ON(!IS_HASWELL(dev)); WARN_ON(!IS_ULT(dev)); - } else { - goto check_next; - } - pci_dev_put(pch); + } else + continue; + break; } -check_next: - pch = pci_get_class(PCI_CLASS_BRIDGE_ISA << 8, curr); - pci_dev_put(curr); } if (!pch) - DRM_DEBUG_KMS("No PCH found?\n"); + DRM_DEBUG_KMS("No PCH found.\n"); + + pci_dev_put(pch); } bool i915_semaphore_is_enabled(struct drm_device *dev) -- 2.20.1