6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Abdurrahman Hussain commit 44081d708b5b885487bac792db78324b7b4c267d upstream. of_overlay_fdt_apply() stores the idr_alloc() return value in ovcs->id before checking it. On failure the stored id is negative, free_overlay_changeset()'s "if (ovcs->id)" check passes, idr_remove() is called with a negative id and list_del() runs on ovcs->ovcs_list, which is not initialized until after the id allocation. An allocation failure at that point dereferences NULL. Make free_overlay_changeset() treat only a strict-positive id as registered. The rest of the function already copes with a partially-initialized ovcs, so the error path stays a plain goto err_free_ovcs. Fixes: 61b4de4e0b38 ("of: overlay: minor restructuring") Cc: stable@vger.kernel.org Suggested-by: Geert Uytterhoeven Assisted-by: Claude:claude-fable-5 [Claude Code] Reviewed-by: Geert Uytterhoeven Signed-off-by: Abdurrahman Hussain Link: https://patch.msgid.link/20260831-nh-of-alias-overlay-v7-5-02754604805a@nexthop.ai Signed-off-by: Rob Herring (Arm) Signed-off-by: Greg Kroah-Hartman --- drivers/of/overlay.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/of/overlay.c +++ b/drivers/of/overlay.c @@ -861,7 +861,8 @@ static void free_overlay_changeset(struc if (ovcs->cset.entries.next) of_changeset_destroy(&ovcs->cset); - if (ovcs->id) { + /* a failed idr_alloc() leaves its negative error in ovcs->id */ + if (ovcs->id > 0) { idr_remove(&ovcs_idr, ovcs->id); list_del(&ovcs->ovcs_list); ovcs->id = 0;