drm/amdgpu: integer overflow in amdgpu_info_ioctl()

The "alloc_size" calculation can overflow leading to memory corruption.

Reviewed-by: Christian König <christian.koenig@amd.com>
Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
index 22367939ebf1..8c735f544b66 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
@@ -390,7 +390,7 @@ static int amdgpu_info_ioctl(struct drm_device *dev, void *data, struct drm_file
                                     min((size_t)size, sizeof(vram_gtt))) ? -EFAULT : 0;
         }
         case AMDGPU_INFO_READ_MMR_REG: {
-                unsigned n, alloc_size = info->read_mmr_reg.count * 4;
+                unsigned n, alloc_size;
                 uint32_t *regs;
                 unsigned se_num = (info->read_mmr_reg.instance >>
                                    AMDGPU_INFO_MMR_SE_INDEX_SHIFT) &
@@ -406,9 +406,10 @@ static int amdgpu_info_ioctl(struct drm_device *dev, void *data, struct drm_file
                 if (sh_num == AMDGPU_INFO_MMR_SH_INDEX_MASK)
                         sh_num = 0xffffffff;
 
-                regs = kmalloc(alloc_size, GFP_KERNEL);
+                regs = kmalloc_array(info->read_mmr_reg.count, sizeof(*regs), GFP_KERNEL);
                 if (!regs)
                         return -ENOMEM;
+                alloc_size = info->read_mmr_reg.count * sizeof(*regs);
 
                 for (i = 0; i < info->read_mmr_reg.count; i++)
                         if (amdgpu_asic_read_register(adev, se_num, sh_num,