linux-kernel - [PATCH 1/3] drm/msm/a6xx: Fix kvzalloc vs state

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Date:   Thu, 13 Oct 2022 15:55:13 -0700
From:   Rob Clark <robdclark@...il.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     linux-arm-msm@...r.kernel.org, freedreno@...ts.freedesktop.org,
        Rob Clark <robdclark@...omium.org>,
        Rob Clark <robdclark@...il.com>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Akhil P Oommen <quic_akhilpo@...cinc.com>,
        Douglas Anderson <dianders@...omium.org>,
        Emma Anholt <emma@...olt.net>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 1/3] drm/msm/a6xx: Fix kvzalloc vs state_kcalloc usage

From: Rob Clark <robdclark@...omium.org>

adreno_show_object() is a trap!  It will re-allocate the pointer it is
passed on first call, when the data is ascii85 encoded, using kvmalloc/
kvfree().  Which means the data *passed* to it must be kvmalloc'd, ie.
we cannot use the state_kcalloc() helper.

This partially reverts
ec8f1813bf8d ("drm/msm/a6xx: Replace kcalloc() with kvzalloc()"), but
fix the missing kvfree() to fix the memory leak that was present
previously.  And adds a warning comment.

Fixes: ec8f1813bf8d ("drm/msm/a6xx: Replace kcalloc() with kvzalloc()")
Closes: https://gitlab.freedesktop.org/drm/msm/-/issues/20
Signed-off-by: Rob Clark <robdclark@...omium.org>
---
 drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c | 11 ++++++++++-
 drivers/gpu/drm/msm/adreno/adreno_gpu.c     |  7 ++++++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c
index 3c112a6cc8a2..730355f9e2d4 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c
@@ -819,7 +819,7 @@ static struct msm_gpu_state_bo *a6xx_snapshot_gmu_bo(
 
 	snapshot->iova = bo->iova;
 	snapshot->size = bo->size;
-	snapshot->data = state_kcalloc(a6xx_state, 1, snapshot->size);
+	snapshot->data = kvzalloc(snapshot->size, GFP_KERNEL);
 	if (!snapshot->data)
 		return NULL;
 
@@ -1034,6 +1034,15 @@ static void a6xx_gpu_state_destroy(struct kref *kref)
 	struct a6xx_gpu_state *a6xx_state = container_of(state,
 			struct a6xx_gpu_state, base);
 
+	if (a6xx_state->gmu_log)
+		kvfree(a6xx_state->gmu_log->data);
+
+	if (a6xx_state->gmu_hfi)
+		kvfree(a6xx_state->gmu_hfi->data);
+
+	if (a6xx_state->gmu_debug)
+		kvfree(a6xx_state->gmu_debug->data);
+
 	list_for_each_entry_safe(obj, tmp, &a6xx_state->objs, node)
 		kvfree(obj);
 
diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
index 382fb7f9e497..5a0e8491cd3a 100644
--- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
@@ -729,7 +729,12 @@ static char *adreno_gpu_ascii85_encode(u32 *src, size_t len)
 	return buf;
 }
 
-/* len is expected to be in bytes */
+/* len is expected to be in bytes
+ *
+ * WARNING: *ptr should be allocated with kvmalloc or friends.  It can be free'd
+ * with kvfree() and replaced with a newly kvmalloc'd buffer on the first call
+ * when the unencoded raw data is encoded
+ */
 void adreno_show_object(struct drm_printer *p, void **ptr, int len,
 		bool *encoded)
 {
-- 
2.37.3