[PATCHv2 -next] drm/amdgpu: double free error and freeing uninitialized null pointer

[Sebin Sebastian]

Fix a double free and an uninitialized pointer read error. Both tmp and
new are pointing at same address and both are freed which leads to
double free. Adding a check to verify if new and tmp are free in the
error_free label fixes the double free issue. new is not initialized to
null which also leads to a free on an uninitialized pointer.

Suggested by: S. Amaranath <amaranath.somalapu...@amd.com>
Signed-off-by: Sebin Sebastian <mailmesebi...@gmail.com>
---
Changes in v2:
Updated patch body as suggested by André Almeida <andrealm...@igalia.com>
Reworked to implement a check in error_free for fixing double free error
as suggested by S. Amaranath <amaranath.somalapu...@amd.com>

 drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
index e2eec985adb3..cb00c7d6f50b 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
@@ -1705,7 +1705,7 @@ 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 *new, *tmp = NULL;
+       uint32_t *new = NULL, *tmp = NULL;
        int ret, i = 0, len = 0;
 
        do {
@@ -1747,7 +1747,8 @@ static ssize_t 
amdgpu_reset_dump_register_list_write(struct file *f,
        ret = size;
 
 error_free:
-       kfree(tmp);
+       if (tmp != new)
+               kfree(tmp);
        kfree(new);
        return ret;
 }
-- 
2.34.1