Created attachment 1328 [details]
HTML part that causes lockup in css_value_list_append

For mails sent by twitter, yammer and the odd spammer, the gtkhtml2 plugin goes into an infinite loop, consuming 100% CPU.  I suspect it has to do with @media optional sections in CSS.

claws-mail does not respond to a kill -TERM signal during this condition, which is a little odd.

Backtrace:

(gdb) bt
#0  0x00007f84d2aec857 in css_value_list_append () from /usr/lib/claws-mail/plugins/gtkhtml2_viewer.so
#1  0x00007f84d2aec08f in css_parser_parse_stylesheet () from /usr/lib/claws-mail/plugins/gtkhtml2_viewer.so
#2  0x00007f84d2aed599 in ?? () from /usr/lib/claws-mail/plugins/gtkhtml2_viewer.so
#3  0x00007f84d2aedb91 in ?? () from /usr/lib/claws-mail/plugins/gtkhtml2_viewer.so
#4  0x00007f84fbc60257 in g_cclosure_marshal_VOID__OBJECTv () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#5  0x00007f84fbc5d3b7 in ?? () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#6  0x00007f84fbc75e82 in g_signal_emit_valist () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#7  0x00007f84fbc76ae2 in g_signal_emit () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#8  0x00007f84d27d8389 in ?? () from /usr/lib/x86_64-linux-gnu/libxml2.so.2
#9  0x00007f84d27dd513 in htmlParseChunk () from /usr/lib/x86_64-linux-gnu/libxml2.so.2
#10 0x00007f84d2b11d75 in html_stream_write () from /usr/lib/claws-mail/plugins/gtkhtml2_viewer.so
#11 0x00007f84d2ae3f89 in ?? () from /usr/lib/claws-mail/plugins/gtkhtml2_viewer.so
#12 0x00007f84fb994f13 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#13 0x00007f84fb9943b6 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#14 0x00007f84fb994708 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#15 0x00007f84fb994b0a in g_main_loop_run () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#16 0x00007f84fdd1a277 in gtk_main () from /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
#17 0x00000000004473d8 in main (argc=1, argv=0x7fff64c7bce8) at main.c:1686
(gdb) n
Single stepping until exit from function css_value_list_append,
which has no line number information.
(never returns)