diff options
| author | Srinivasan Shanmugam <srinivasan.shanmugam@amd.com> | 2025-10-23 19:54:16 +0530 |
|---|---|---|
| committer | Alex Deucher <alexander.deucher@amd.com> | 2025-10-28 10:02:21 -0400 |
| commit | dfc74e37bdb487eed5ad90d0eac4055f60217fb0 (patch) | |
| tree | a5ab38641b9567c87d68cfabca0952d7421bb3ca | |
| parent | 1017e393ad6d61756f7f35a6eb059a42a40818e6 (diff) | |
drm/amdkfd: Fix use-after-free of HMM range in svm_range_validate_and_map()
The function svm_range_validate_and_map() was freeing `range` when
amdgpu_hmm_range_get_pages() failed. But later, the code still used the
same `range` pointer and freed it again. This could cause a
use-after-free and double-free issue.
The fix sets `range = NULL` right after it is freed and checks for
`range` before using or freeing it again.
v2: Removed duplicate !r check in the condition for clarity.
v3: In amdgpu_hmm_range_get_pages(), when hmm_range_fault() fails, we
kvfree(pfns) but leave the pointer in hmm_range->hmm_pfns still pointing
to freed memory. The caller (or amdgpu_hmm_range_free(range)) may try to
free range->hmm_range.hmm_pfns again, causing a double free, Setting
hmm_range->hmm_pfns = NULL immediately after kvfree(pfns) prevents both
double free. (Philip)
In svm_range_validate_and_map(), When r == 0, it means success → range
is not NULL. When r != 0, it means failure → already made range = NULL.
So checking both (!r && range) is unnecessary because the moment r == 0,
we automatically know range exists and is safe to use. (Philip)
Fixes: 737da5363cc0 ("drm/amdgpu: update the functions to use amdgpu version of hmm")
Reported by: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Philip Yang <Philip.Yang@amd.com>
Cc: Sunil Khatri <sunil.khatri@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Philip Yang<Philip.Yang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
| -rw-r--r-- | drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.c | 1 | ||||
| -rw-r--r-- | drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 6 |
2 files changed, 5 insertions, 2 deletions
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.c index 7e5a09b0bc78..518ca3f4db2b 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.c @@ -221,6 +221,7 @@ retry: out_free_pfns: kvfree(pfns); + hmm_range->hmm_pfns = NULL; out_free_range: if (r == -EBUSY) r = -EAGAIN; diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c index 729aac81563c..ffb7b36e577c 100644 --- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c +++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c @@ -1746,6 +1746,7 @@ static int svm_range_validate_and_map(struct mm_struct *mm, WRITE_ONCE(p->svms.faulting_task, NULL); if (r) { amdgpu_hmm_range_free(range); + range = NULL; pr_debug("failed %d to get svm range pages\n", r); } } else { @@ -1763,7 +1764,7 @@ static int svm_range_validate_and_map(struct mm_struct *mm, svm_range_lock(prange); /* Free backing memory of hmm_range if it was initialized - * Overrride return value to TRY AGAIN only if prior returns + * Override return value to TRY AGAIN only if prior returns * were successful */ if (range && !amdgpu_hmm_range_valid(range) && !r) { @@ -1771,7 +1772,8 @@ static int svm_range_validate_and_map(struct mm_struct *mm, r = -EAGAIN; } /* Free the hmm range */ - amdgpu_hmm_range_free(range); + if (range) + amdgpu_hmm_range_free(range); if (!r && !list_empty(&prange->child_list)) { |