The heap ID is used to index the heap context pool, and allocating
in the [1:MAX_HEAPS_PER_POOL] leads to an off-by-one. This was
originally to avoid returning a zero heap handle, but given the handle
is formed with (vm_id << 16) | heap_id, with vm_id > 0, we already can't
end up with a valid heap handle that's zero.
v3:
- Allocate in the [0:MAX_HEAPS_PER_POOL-1] range
v2:
- New patch
Fixes: 9cca48fa4f89 ("drm/panthor: Add the heap logical block")
Reported-by: Eric Smith <eric.smith@xxxxxxxxxxxxx>
Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
Tested-by: Eric Smith <eric.smith@xxxxxxxxxxxxx>
---
drivers/gpu/drm/panthor/panthor_heap.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/panthor/panthor_heap.c b/drivers/gpu/drm/panthor/panthor_heap.c
index 683bb94761bc..252332f5390f 100644
--- a/drivers/gpu/drm/panthor/panthor_heap.c
+++ b/drivers/gpu/drm/panthor/panthor_heap.c
@@ -323,7 +323,8 @@ int panthor_heap_create(struct panthor_heap_pool *pool,
if (!pool->vm) {
ret = -EINVAL;
} else {
- ret = xa_alloc(&pool->xa, &id, heap, XA_LIMIT(1, MAX_HEAPS_PER_POOL), GFP_KERNEL);
+ ret = xa_alloc(&pool->xa, &id, heap,
+ XA_LIMIT(0, MAX_HEAPS_PER_POOL - 1), GFP_KERNEL);
if (!ret) {
void *gpu_ctx = panthor_get_heap_ctx(pool, id);
--
2.44.0
