From b49cb0ab9c165c1e861b5dfac5eb7ef6cb9e4e3a Mon Sep 17 00:00:00 2001 From: Noam Postavsky Date: Sat, 4 Jun 2016 09:02:20 -0400 Subject: [PATCH] Fbackward_prefix_chars: stay within buffer bounds The commit 1fd3172d "(Fbackward_prefix_chars): Set point properly while scanning" (1998-03-18), moved the check against of the position against the buffer beginning out the loop condition so that we might end up checking the syntax of characters before the beginning of the buffer. This can cause segfaults or trigger a "Point before start of properties" error in `update_interval' (called indirectly from `char_quoted'). * src/syntax.c (Fbackward_prefix_chars): Stop the loop when beginning of buffer is reached (Bug #3552, Bug #17132, Bug #19379). --- src/syntax.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/src/syntax.c b/src/syntax.c index 0af2a21a220..6e133ad9c27 100644 --- a/src/syntax.c +++ b/src/syntax.c @@ -3098,8 +3098,9 @@ the prefix syntax flag (p). */) opoint = pos; opoint_byte = pos_byte; - if (pos + 1 > beg) - DEC_BOTH (pos, pos_byte); + if (pos <= beg) + break; + DEC_BOTH (pos, pos_byte); } SET_PT_BOTH (opoint, opoint_byte); -- 2.11.4.GIT