Another undo list UAF

[Grisha Levit]

Another undo list UAF. Related, I think, to edit-and-execute-command.

HISTFILE= INPUTRC=/ bash --norc -in <<< $' \n\cP \cN\cP\cU\cX\cE\n\e<'

AddressSanitizer: heap-use-after-free on address 0xe09245621f48
READ of size 4 at 0xe09245621f48 thread T0
    #0 0xb168908a6edc in rl_do_undo lib/readline/undo.c:188:25
    #1 0xb168908a8c50 in rl_revert_line lib/readline/undo.c:339:2
    #2 0xb168907c7cb8 in readline_common_teardown lib/readline/readline.c:493:7
    ...