Did you recompile antispam plugin? Is it the latest antispam? This line doesn't seem to match the current code.
You are correct, it had not been compiled in a while. Here is a new backtrace:
(gdb) bt full #0 0x0000000010709ebc in kill () from /lib/libc.so.7 No symbol table info available. #1 0x0000000010708e43 in abort () from /lib/libc.so.7 No symbol table info available. #2 0x00000000105b8e65 in default_fatal_finish.14395 () from /usr/lib/dovecot/libdovecot.so.0 No symbol table info available. #3 0x0000000010588e3d in i_internal_fatal_handler.14399 () from /usr/lib/dovecot/libdovecot.so.0 No symbol table info available. #4 0x00000000105e4941 in i_panic () from /usr/lib/dovecot/libdovecot.so.0 No symbol table info available. #5 0x00000000105e7c77 in buffer_check_limits.13467 () from /usr/lib/dovecot/libdovecot.so.0 No symbol table info available. #6 0x00000000105e7a6a in buffer_write () from /usr/lib/dovecot/libdovecot.so.0 No symbol table info available. #7 0x00000000105ce9f9 in array_idx_set_i () from /usr/lib/dovecot/libdovecot.so.0 No symbol table info available. #8 0x0000000010e2a1b5 in antispam_user_created (user=0x10a83040) at user.c:96 _module_tmp = (void *) 0x10a84d18 asu = (struct antispam_user *) 0x10a84d18 tmp = Variable "tmp" is not available.
Cheers,
Olivier