From 93005cd9dc2bab882e66ac7b81f593cd6c021e43 Mon Sep 17 00:00:00 2001 From: Stefan Monnier Date: Tue, 9 May 2023 22:30:52 -0400 Subject: [PATCH] with-display-message: Workaround for bug#63253 Running arbitrary ELisp code from an atimer is still dangerous, at least because the regexp engine is not-reentrant, so let's patch up the case we bumped into. There are probably many other such holes :-( * src/alloc.c (garbage_collection_inhibited): Make it non-static. * src/xdisp.c (garbage_collection_inhibited): Declare it. (set_message, clear_message): Use it as a proxy for "we're in a dangerous context like within `probably_quit`". --- src/alloc.c | 2 +- src/xdisp.c | 12 ++++++++++-- 2 files changed, 11 insertions(+), 3 deletions(-) diff --git a/src/alloc.c b/src/alloc.c index 05a19f0b7e9..7ff2cd3b100 100644 --- a/src/alloc.c +++ b/src/alloc.c @@ -367,7 +367,7 @@ static ptrdiff_t pure_bytes_used_non_lisp; /* If positive, garbage collection is inhibited. Otherwise, zero. */ -static intptr_t garbage_collection_inhibited; +intptr_t garbage_collection_inhibited; /* The GC threshold in bytes, the last time it was calculated from gc-cons-threshold and gc-cons-percentage. */ diff --git a/src/xdisp.c b/src/xdisp.c index 43847544396..e960901d5dc 100644 --- a/src/xdisp.c +++ b/src/xdisp.c @@ -12810,6 +12810,8 @@ truncate_message_1 (void *a1, Lisp_Object a2) return false; } +extern intptr_t garbage_collection_inhibited; + /* Set the current message to STRING. */ static void @@ -12819,7 +12821,11 @@ set_message (Lisp_Object string) eassert (STRINGP (string)); - if (FUNCTIONP (Vset_message_function)) + if (FUNCTIONP (Vset_message_function) + /* FIXME: (bug#63253) We should really make the regexp engine re-entrant, + but in the mean time, let's ignore `set-message-function` when + called from `probably_quit`. */ + && !garbage_collection_inhibited) { specpdl_ref count = SPECPDL_INDEX (); specbind (Qinhibit_quit, Qt); @@ -12896,7 +12902,9 @@ clear_message (bool current_p, bool last_displayed_p) if (current_p) { - if (FUNCTIONP (Vclear_message_function)) + if (FUNCTIONP (Vclear_message_function) + /* FIXME: (bug#63253) Same as for `set-message-function` above. */ + && !garbage_collection_inhibited) { specpdl_ref count = SPECPDL_INDEX (); specbind (Qinhibit_quit, Qt); -- 2.39.2