Use After Free in the drag source path of the drag and drop protocol in kitty from 0.47.0 before 0.49.0 allows a program writing to the terminal to cause the terminal to read from and write to freed heap memory, because drag_remote_file_data() in kitty/dnd.c holds a DragRemoteItem pointer into an array it does not own, calls toplevel_data_for_drag() or subdir_data_for_drag(), and then continues to use that pointer. Those helpers, and add_payload() and populate_dir_entries() which they call, report errors through the abrt() macro, which expands to cancel_drag() followed by a plain return, and cancel_drag() calls drag_free_offer(), which frees the array the pointer refers to. The helpers return void, so the caller receives no indication that the teardown happened, and proceeds to call all_children_complete() on the freed pointer, which dereferences it, and then to write through it. That dereference is guarded by a local flag that is set when the request carries no payload and announces no further data, which is the same condition that selects the finalisation block of add_payload(), so the error paths in that block reach it: a create that fails because an entry of the same name already exists, because the client may declare two entries with one name and the create operations use O_CREAT with O_EXCL and symlinkat(), a mkdirat() failure other than EEXIST, and the directory entry allocation paths. Both branches reach it. In the top level branch the caller's pointer is never clear…

Use After Free in the drag source path of the drag and drop protocol in kitty from 0.47.0 before 0.49.0 allows a program writing to the terminal to cause the terminal to read from and write to freed heap memory, because drag_remote_file_data() in kitty/dnd.c holds a DragRemoteItem pointer into an array it does not own, calls toplevel_data_for_drag() or subdir_data_for_drag(), and then continues to use that pointer. Those helpers, and add_payload() and populate_dir_entries() which they call, report errors through the abrt() macro, which expands to cancel_drag() followed by a plain return, and cancel_drag() calls drag_free_offer(), which frees the array the pointer refers to. The helpers return void, so the caller receives no indication that the teardown happened, and proceeds to call all_children_complete() on the freed pointer, which dereferences it, and then to write through it. That dereference is guarded by a local flag that is set when the request carries no payload and announces no further data, which is the same condition that selects the finalisation block of add_payload(), so the error paths in that block reach it: a create that fails because an entry of the same name already exists, because the client may declare two entries with one name and the create operations use O_CREAT with O_EXCL and symlinkat(), a mkdirat() failure other than EEXIST, and the directory entry allocation paths. Both branches reach it. In the top level branch the caller's pointer is never clear…