From 85f4cf41a852b5983ca436615a019315f6dc7301 Mon Sep 17 00:00:00 2001 From: Tom de Vries Date: Sun, 28 May 2023 10:17:57 +0200 Subject: [readline] Fix double free in _rl_scxt_dispose Consider the following scenario. We start gdb in TUI mode: ... $ gdb -q -tui ... and type ^R which gives us the reverse-isearch prompt in the cmd window: ... (reverse-i-search)`': ... and then type "foo", right-arrow-key, and ^C. In TUI mode, gdb uses a custom rl_getc_function tui_getc. When pressing the right-arrow-key, tui_getc: - attempts to scroll the TUI src window, without any effect, and - returns 0. The intention of returning 0 is mentioned here in tui_dispatch_ctrl_char: ... /* We intercepted the control character, so return 0 (which readline will interpret as a no-op). */ return 0; ... However, after this 0 is returned by the rl_read_key () call in _rl_search_getchar, _rl_read_mbstring is called, which incorrectly interprets 0 as the first part of an utf-8 multibyte char, and tries to read the next char. In this state, the ^C takes effect and we run into a double free because _rl_isearch_cleanup is called twice. Both these issues need fixing independently, though after fixing the first we no longer trigger the second. The first issue is caused by the subtle difference between: - a char array containing 0 chars, which is zero-terminated, and - a char array containing 1 char, which is zero. In mbrtowc terms, this is the difference between: ... mbrtowc (&wc, "", 0, &ps); ... which returns -2, and: ... mbrtowc (&wc, "", 1, &ps); ... which returns 0. Note that _rl_read_mbstring calls _rl_get_char_len without passing it an explicit length parameter, and consequently it cannot distinguish between the two, and defaults to the "0 chars" choice. Note that the same problem doesn't exist in _rl_read_mbchar. Fix this by defaulting to the "1 char" choice in _rl_get_char_len: ... - if (_rl_utf8locale && l > 0 && UTF8_SINGLEBYTE(*src)) + if (_rl_utf8locale && l >= 0 && UTF8_SINGLEBYTE(*src)) ... The second problem happens when the call to _rl_search_getchar in _rl_isearch_callback returns. At that point _rl_isearch_cleanup has already been called from the signal handler, but we proceed regardless, using a cxt pointer that has been freed. Fix this by checking for "RL_ISSTATE (RL_STATE_ISEARCH)" after the call to _rl_search_getchar: ... c = _rl_search_getchar (cxt); + if (!RL_ISSTATE (RL_STATE_ISEARCH)) + return 1; ... Tested on x86_64-linux. Approved-By: Chet Ramey PR tui/30056 Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30056 --- readline/readline/isearch.c | 3 +++ readline/readline/mbutil.c | 2 +- 2 files changed, 4 insertions(+), 1 deletion(-) (limited to 'readline') diff --git a/readline/readline/isearch.c b/readline/readline/isearch.c index 080ba3c..941078f 100644 --- a/readline/readline/isearch.c +++ b/readline/readline/isearch.c @@ -882,6 +882,9 @@ _rl_isearch_callback (_rl_search_cxt *cxt) int c, r; c = _rl_search_getchar (cxt); + if (!RL_ISSTATE (RL_STATE_ISEARCH)) + return 1; + /* We might want to handle EOF here */ r = _rl_isearch_dispatch (cxt, cxt->lastc); diff --git a/readline/readline/mbutil.c b/readline/readline/mbutil.c index dc62b4c..7da3ff1 100644 --- a/readline/readline/mbutil.c +++ b/readline/readline/mbutil.c @@ -363,7 +363,7 @@ _rl_get_char_len (char *src, mbstate_t *ps) /* Look at no more than MB_CUR_MAX characters */ l = (size_t)strlen (src); - if (_rl_utf8locale && l > 0 && UTF8_SINGLEBYTE(*src)) + if (_rl_utf8locale && l >= 0 && UTF8_SINGLEBYTE(*src)) tmp = (*src != 0) ? 1 : 0; else { -- cgit v1.1