drm/ttm: fix bulk_move corruption when adding a entry

commit 4481913607e58196c48a4fef5e6f45350684ec3c upstream.

When the resource is the first in the bulk_move range, adding it again
(thus moving it to the tail) will corrupt the list since the first
pointer is not moved. This eventually lead to null pointer deref in
ttm_lru_bulk_move_del()

Fixes: fee2ede15542 ("drm/ttm: rework bulk move handling v5")
Signed-off-by: Yunxiang Li <Yunxiang.Li@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
CC: stable@vger.kernel.org
Link: https://patchwork.freedesktop.org/patch/msgid/20230622141902.28718-3-Yunxiang.Li@amd.com
Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/ttm/ttm_resource.c b/drivers/gpu/drm/ttm/ttm_resource.c
index a729c32a1e48a6995169c1269caa59a4b39b34d6..3287032a2f8e8ee817a3b6c8ce4354abfec94b4b 100644 (file)
--- a/drivers/gpu/drm/ttm/ttm_resource.c
+++ b/drivers/gpu/drm/ttm/ttm_resource.c
@@ -85,6 +85,8 @@ static void ttm_lru_bulk_move_pos_tail(struct ttm_lru_bulk_move_pos *pos,
                                       struct ttm_resource *res)
 {
        if (pos->last != res) {
+               if (pos->first == res)
+                       pos->first = list_next_entry(res, lru);
                list_move(&res->lru, &pos->last->lru);
                pos->last = res;
        }
@@ -110,7 +112,8 @@ static void ttm_lru_bulk_move_del(struct ttm_lru_bulk_move *bulk,
 {
        struct ttm_lru_bulk_move_pos *pos = ttm_lru_bulk_move_pos(bulk, res);
 
-       if (unlikely(pos->first == res && pos->last == res)) {
+       if (unlikely(WARN_ON(!pos->first || !pos->last) ||
+                    (pos->first == res && pos->last == res))) {
                pos->first = NULL;
                pos->last = NULL;
        } else if (pos->first == res) {