From 5bbc6604a62814511c32f2e39bc9ffb2c1b92cbe Mon Sep 17 00:00:00 2001
From: Tom St Denis <tom.stdenis@amd.com>
Date: Tue, 10 Mar 2020 08:40:41 -0400
Subject: drm/amd/amdgpu: Fix GPR read from debugfs (v2)
MIME-Version: 1.0
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Content-Transfer-Encoding: 8bit
Git-commit: 5bbc6604a62814511c32f2e39bc9ffb2c1b92cbe
Patch-mainline: v5.6-rc7
References: bsc#1113956

The offset into the array was specified in bytes but should
be in terms of 32-bit words.  Also prevent large reads that
would also cause a buffer overread.

v2:  Read from correct offset from internal storage buffer.

Signed-off-by: Tom St Denis <tom.stdenis@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
index f24ed9a1a3e56..337d7cdce8e9c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
@@ -781,11 +781,11 @@ 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 > 4096 || size & 3 || *pos & 3)
 		return -EINVAL;
 
 	/* decode offset */
-	offset = *pos & GENMASK_ULL(11, 0);
+	offset = (*pos & GENMASK_ULL(11, 0)) >> 2;
 	se = (*pos & GENMASK_ULL(19, 12)) >> 12;
 	sh = (*pos & GENMASK_ULL(27, 20)) >> 20;
 	cu = (*pos & GENMASK_ULL(35, 28)) >> 28;
@@ -823,7 +823,7 @@ static ssize_t amdgpu_debugfs_gpr_read(struct file *f, char __user *buf,
 	while (size) {
 		uint32_t value;
 
-		value = data[offset++];
+		value = data[result >> 2];
 		r = put_user(value, (uint32_t *)buf);
 		if (r) {
 			result = r;
-- 
2.26.0