Clean up and apply the fix for PR 83477. The calculation for locating

the start of the section headers has to take into account the fact
that the image_nt_header is really variable sized. It happens that
the existing calculation is correct for _most_ production binaries
produced by the Windows DDK, but if we get a binary with oddball
offsets, the PE loader could crash.

Changes from the supplied patch are:

- We don't really need to use the IMAGE_SIZEOF_NT_HEADER() macro when
  computing how much of the header to return to callers of
  pe_get_optional_header(). While it's important to take the variable
  size of the header into account in other calculations, we never
  actually look at anything outside the non-variable portion of the
  header. This saves callers from having to allocate a variable sized
  buffer off the heap (I purposely tried to avoid using malloc()
  in subr_pe.c to make it easier to compile in both the -D_KERNEL and
  !-D_KERNEL case), and since we're copying into a buffer on the
  stack, we always have to copy the same amount of data or else
  we'll trash the stack something fierce.

- We need <stddef.h> to get offsetof() in the !-D_KERNEL case.

- ndiscvt.c needs the IMAGE_FIRST_SECTION() macro too, since it does
  a little bit of section pre-processing.

PR: kern/83477

1 files changed, 2 insertions, 2 deletions

diff --git a/usr.sbin/ndiscvt/ndiscvt.c b/usr.sbin/ndiscvt/ndiscvt.c
index 090f0834f660..80eae836f080 100644
--- a/usr.sbin/ndiscvt/ndiscvt.c
+++ b/usr.sbin/ndiscvt/ndiscvt.c
@@ -38,6 +38,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/socket.h>
 #include <net/if.h>
 #include <stdlib.h>
+#include <stddef.h>
 #include <unistd.h>
 #include <stdio.h>
 #include <errno.h>
@@ -88,8 +89,7 @@ extern const char *__progname;
 #define SET_HDRS(x)	\
 	dos_hdr = (image_dos_header *)x;				\
 	nt_hdr = (image_nt_header *)(x + dos_hdr->idh_lfanew);		\
-	sect_hdr = (image_section_header *)((vm_offset_t)nt_hdr +	\
-	    sizeof(image_nt_header));
+	sect_hdr = IMAGE_FIRST_SECTION(nt_hdr);
 
 static
 int insert_padding(imgbase, imglen)