[PATCH] drm/amd/amdgpu: Fix amdgpu_debugfs_gpr_read debugfs entry

[Tom St Denis]

We don't need to check the alignment of the offset and there was
potential a buffer overflow as well.

Signed-off-by: Tom St Denis <tom.stdenis at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
index c98e59721444..b1ea300008e5 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
@@ -507,6 +507,9 @@ static ssize_t amdgpu_debugfs_wave_read(struct file *f, char __user *buf,
 	return result;
 }
 
+// read at most 1024 words
+#define AMDGPU_DEBUGFS_MAX_SGPR_READ 1024
+
 static ssize_t amdgpu_debugfs_gpr_read(struct file *f, char __user *buf,
 					size_t size, loff_t *pos)
 {
@@ -515,7 +518,7 @@ static ssize_t amdgpu_debugfs_gpr_read(struct file *f, char __user *buf,
 	ssize_t result = 0;
 	uint32_t offset, se, sh, cu, wave, simd, thread, bank, *data;
 
-	if (size & 3 || *pos & 3)
+	if (size & 3 || size > (4 * AMDGPU_DEBUGFS_MAX_SGPR_READ))
 		return -EINVAL;
 
 	/* decode offset */
@@ -528,7 +531,8 @@ static ssize_t amdgpu_debugfs_gpr_read(struct file *f, char __user *buf,
 	thread = (*pos & GENMASK_ULL(59, 52)) >> 52;
 	bank = (*pos & GENMASK_ULL(61, 60)) >> 60;
 
-	data = kmalloc_array(1024, sizeof(*data), GFP_KERNEL);
+	data = kmalloc_array(AMDGPU_DEBUGFS_MAX_SGPR_READ, sizeof(*data),
+						 GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
 
-- 
2.14.3