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authorFlorian Weimer <fweimer@redhat.com>2016-06-23 20:01:40 +0200
committerFlorian Weimer <fweimer@redhat.com>2016-06-23 20:01:52 +0200
commitdb3476aff19b75c4fdefbe65fcd5f0a90588ba51 (patch)
tree5cefd4971a0e6b5d5f9eacf6d3532c6aedc7b352 /libio/iofdopen.c
parent64ba17317dc9343f0958755ad04af71ec3da637b (diff)
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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.
Diffstat (limited to 'libio/iofdopen.c')
-rw-r--r--libio/iofdopen.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/libio/iofdopen.c b/libio/iofdopen.c
index e00f337..a4b6757 100644
--- a/libio/iofdopen.c
+++ b/libio/iofdopen.c
@@ -153,15 +153,15 @@ _IO_new_fdopen (int fd, const char *mode)
(use_mmap && (read_write & _IO_NO_WRITES)) ? &_IO_file_jumps_maybe_mmap :
#endif
&_IO_file_jumps;
- _IO_file_init (&new_f->fp);
+ _IO_new_file_init_internal (&new_f->fp);
#if !_IO_UNIFIED_JUMPTABLES
new_f->fp.vtable = NULL;
#endif
- /* We only need to record the fd because _IO_file_init will have unset the
- offset. It is important to unset the cached offset because the real
- offset in the file could change between now and when the handle is
- activated and we would then mislead ftell into believing that we have a
- valid offset. */
+ /* We only need to record the fd because _IO_file_init_internal will
+ have unset the offset. It is important to unset the cached
+ offset because the real offset in the file could change between
+ now and when the handle is activated and we would then mislead
+ ftell into believing that we have a valid offset. */
new_f->fp.file._fileno = fd;
new_f->fp.file._flags &= ~_IO_DELETE_DONT_CLOSE;