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From:   trix@redhat.com
To:     alexander.deucher@amd.com, christian.koenig@amd.com,
        Xinhui.Pan@amd.com, airlied@linux.ie, daniel@ffwll.ch,
        nathan@kernel.org, ndesaulniers@google.com, lijo.lazar@amd.com,
        nirmoy.das@amd.com, kevin1.wang@amd.com, tom.stdenis@amd.com,
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Cc:     amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
        Tom Rix <trix@redhat.com>
Subject: [PATCH v2] drm/amdgpu: Fix realloc of ptr
Date:   Sun, 27 Feb 2022 07:33:42 -0800
Message-Id: <20220227153342.79546-1-trix@redhat.com>
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From: Tom Rix <trix@redhat.com>

Clang static analysis reports this error
amdgpu_debugfs.c:1690:9: warning: 1st function call
  argument is an uninitialized value
  tmp = krealloc_array(tmp, i + 1,
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~

realloc uses tmp, so tmp can not be garbage.
And the return needs to be checked.

Fixes: 5ce5a584cb82 ("drm/amdgpu: add debugfs for reset registers list")
Signed-off-by: Tom Rix <trix@redhat.com>
---
v2:
  use 'new' to hold/check the ralloc return
  fix commit log mistake on ralloc freeing to using input ptr
  
 drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
index 9eb9b440bd438..2f4f8c5618d81 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
@@ -1676,7 +1676,7 @@ static ssize_t amdgpu_reset_dump_register_list_write(struct file *f,
 {
 	struct amdgpu_device *adev = (struct amdgpu_device *)file_inode(f)->i_private;
 	char reg_offset[11];
-	uint32_t *tmp;
+	uint32_t *new, *tmp = NULL;
 	int ret, i = 0, len = 0;
 
 	do {
@@ -1687,7 +1687,12 @@ static ssize_t amdgpu_reset_dump_register_list_write(struct file *f,
 			goto error_free;
 		}
 
-		tmp = krealloc_array(tmp, i + 1, sizeof(uint32_t), GFP_KERNEL);
+		new = krealloc_array(tmp, i + 1, sizeof(uint32_t), GFP_KERNEL);
+		if (!new) {
+			ret = -ENOMEM;
+			goto error_free;
+		}
+		tmp = new;
 		if (sscanf(reg_offset, "%X %n", &tmp[i], &ret) != 1) {
 			ret = -EINVAL;
 			goto error_free;
-- 
2.26.3