Re: [PATCH] drm/amd/amdkfd: Fix a resource leak in svm_range_validate_and_map()

[Felix Kuehling]

On 2024-04-30 19:29, Ramesh Errabolu wrote:
Analysis of code by Coverity, a static code analyser, has identified
a resource leak in the symbol hmm_range. This leak occurs when one of
the prior steps before it is released encounters an error.

Signed-off-by: Ramesh Errabolu <ramesh.errab...@amd.com>
---
  drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 6 ++++--
  1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c 
b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
index 386875e6eb96..dcb1d5d3f860 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
@@ -1658,7 +1658,7 @@ static int svm_range_validate_and_map(struct mm_struct 
*mm,
        start = map_start << PAGE_SHIFT;
        end = (map_last + 1) << PAGE_SHIFT;
        for (addr = start; !r && addr < end; ) {
-               struct hmm_range *hmm_range;
+               struct hmm_range *hmm_range = NULL;
                unsigned long map_start_vma;
                unsigned long map_last_vma;
                struct vm_area_struct *vma;
@@ -1696,7 +1696,9 @@ static int svm_range_validate_and_map(struct mm_struct 
*mm,
                }
  
  		svm_range_lock(prange);
-               if (!r && amdgpu_hmm_range_get_pages_done(hmm_range)) {
+
+               // Free backing memory of hmm_range if it was initialized
+               if (hmm_range && amdgpu_hmm_range_get_pages_done(hmm_range)) {
                        pr_debug("hmm update the range, need validate again\n");
                        r = -EAGAIN;

Nack! This can now override other error codes that aren't meant to be 
overridden with -EAGAIN.

I think a better solution would be to just revserse this condition to 
ensure that amdgpu_hmm_range_get_pages_done is always called:

                if (amdgpu_hmm_range_get_pages_done(hmm_range) && !r) {
                        ...
                        r = -EAGAIN;
                }

Regards,
  Felix

                }