From db3476aff19b75c4fdefbe65fcd5f0a90588ba51 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Thu, 23 Jun 2016 20:01:40 +0200 Subject: libio: Implement vtable verification [BZ #20191] This commit puts all libio vtables in a dedicated, read-only ELF section, so that they are consecutive in memory. Before any indirect jump, the vtable pointer is checked against the section boundaries, and the process is terminated if the vtable pointer does not fall into the special ELF section. To enable backwards compatibility, a special flag variable (_IO_accept_foreign_vtables), protected by the pointer guard, avoids process termination if libio stream object constructor functions have been called earlier. Such constructor functions are called by the GCC 2.95 libstdc++ library, and this mechanism ensures compatibility with old binaries. Existing callers inside glibc of these functions are adjusted to call the original functions, not the wrappers which enable vtable compatiblity. The compatibility mechanism is used to enable passing FILE * objects across a static dlopen boundary, too. --- libio/strops.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'libio/strops.c') diff --git a/libio/strops.c b/libio/strops.c index 0932d4c1b1..2ba3704dd2 100644 --- a/libio/strops.c +++ b/libio/strops.c @@ -323,7 +323,7 @@ _IO_str_finish (_IO_FILE *fp, int dummy) _IO_default_finish (fp, 0); } -const struct _IO_jump_t _IO_str_jumps = +const struct _IO_jump_t _IO_str_jumps libio_vtable = { JUMP_INIT_DUMMY, JUMP_INIT(finish, _IO_str_finish), -- cgit v1.2.3