Às 12:06 de 14/07/22, Sebin Sebastian escreveu:
> On Tue, Jul 12, 2022 at 12:14:27PM -0300, André Almeida wrote:
>> Hi Sebin,
>>
>> Às 10:29 de 10/07/22, Sebin Sebastian escreveu:
>>> Fix two coverity warning's double free and and an uninitialized pointer
>>> read. Both tmp and new are pointing at same address and both are freed
>>> which leads to double free. Freeing tmp in the condition after new is
>>> assigned with new address fixes the double free issue. new is not
>>> initialized to null which also leads to a free on an uninitialized
>>> pointer.
>>> Coverity issue: 1518665 (uninitialized pointer read)
>>> 1518679 (double free)
>>
>> What are those numbers?
>>
> These numbers are the issue ID's for the errors that are being reported
> by the coverity static analyzer tool.
>
I see, but I don't know which tool was used, so those seem like random
number to me. I would just remove this part of your commit message, but
if you want to keep it, you need to at least mention what's the tool.
>>>
>>> Signed-off-by: Sebin Sebastian <mailmesebin00@xxxxxxxxx>
>>> ---
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c | 8 +++++---
>>> 1 file changed, 5 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
>>> index f3b3c688e4e7..d82fe0e1b06b 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
>>> @@ -1660,7 +1660,7 @@ 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 {
>>> @@ -1692,17 +1692,19 @@ static ssize_t amdgpu_reset_dump_register_list_write(struct file *f,
>>> goto error_free;
>>> }
>>
>> If the `if (!new) {` above this line is true, will be tmp freed?
>>
> Yes, It doesn't seem to free tmp here. Should I free tmp immediately
> after the do while loop and remove `kfree(tmp)` from the `if (ret)`
> block? Thanks for pointing out the errors.
If you free immediately after the while loop, then you would risk a use
after free here:
swap(adev->reset_dump_reg_list, tmp);
So this isn't the solution either.
>
>>> ret = down_write_killable(&adev->reset_domain->sem);
>>> - if (ret)
>>> + if (ret) {
>>> + kfree(tmp);
>>> goto error_free;
>>> + }
>>>
>>> swap(adev->reset_dump_reg_list, tmp);
>>> swap(adev->reset_dump_reg_value, new);
>>> adev->num_regs = i;
>>> up_write(&adev->reset_domain->sem);
>>> + kfree(tmp);
>>> ret = size;
>>>
>>> error_free:
>>> - kfree(tmp);
>>> kfree(new);
>>> return ret;
>>> }
