linux-kernel - [PATCH] drm/amdgpu/virt: don't dereference undefined 'module' struct

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Message-Id: <20171102112619.72157-1-arnd@arndb.de>
Date:   Thu,  2 Nov 2017 12:25:39 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>
Cc:     Arnd Bergmann <arnd@...db.de>, David Airlie <airlied@...ux.ie>,
        Monk Liu <Monk.Liu@....com>,
        Xiangliang Yu <Xiangliang.Yu@....com>,
        Horace Chen <horace.chen@....com>,
        amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] drm/amdgpu/virt: don't dereference undefined 'module' struct

Accessing the THIS_MODULE directly is only possible when modules
are enabled, otherwise we get a build failure:

drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c: In function 'amdgpu_virt_init_data_exchange':
drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c:331:20: error: dereferencing pointer to incomplete type 'struct module'

Further, THIS_MODULE is NULL when the driver is built-in, so the
code would likely cause a NULL pointer dereference.

This adds an #ifdef check to avoid the compile-time error, plus
a NULL pointer check before dereferencing THIS_MODULE. It might
be better to find a way to avoid using the module version
altogether.

Fixes: 2dc8f81e4f82 ("drm/amdgpu: SR-IOV data exchange between PF&VF")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
index e97f80f86005..4e4a476593e8 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
@@ -328,9 +328,11 @@ void amdgpu_virt_init_data_exchange(struct amdgpu_device *adev)
 					sizeof(amdgim_vf2pf_info));
 				AMDGPU_FW_VRAM_VF2PF_READ(adev, driver_version,
 					&str);
+#ifdef MODULE
 				if (THIS_MODULE->version != NULL)
 					strcpy(str, THIS_MODULE->version);
 				else
+#endif
 					strcpy(str, "N/A");
 				AMDGPU_FW_VRAM_VF2PF_WRITE(adev, driver_cert,
 					0);
-- 
2.9.0