Index: libexec/rtld-elf/map_object.c
===================================================================
--- libexec/rtld-elf/map_object.c
+++ libexec/rtld-elf/map_object.c
@@ -38,7 +38,7 @@
 #include "debug.h"
 #include "rtld.h"
 
-static Elf_Ehdr *get_elf_header(int, const char *, const struct stat *);
+static int get_elf_header(int, const char *, Elf_Ehdr **, size_t *);
 static int convert_flags(int); /* Elf flags -> mmap flags */
 
 int __getosreldate(void);
@@ -56,6 +56,7 @@
 {
     Obj_Entry *obj;
     Elf_Ehdr *hdr;
+    size_t hdrsize;
     int i;
     Elf_Phdr *phdr;
     Elf_Phdr *phlimit;
@@ -91,9 +92,10 @@
     Elf_Addr note_end;
     char *note_map;
     size_t note_map_len;
+    int error;
 
-    hdr = get_elf_header(fd, path, sb);
-    if (hdr == NULL)
+    error = get_elf_header(fd, path, &hdr, &hdrsize);
+    if (error != 0)
 	return (NULL);
 
     /*
@@ -153,8 +155,8 @@
 	    break;
 
 	case PT_NOTE:
-	    if (phdr->p_offset > PAGE_SIZE ||
-	      phdr->p_offset + phdr->p_filesz > PAGE_SIZE) {
+	    if (phdr->p_offset > hdrsize ||
+	      phdr->p_offset + phdr->p_filesz > hdrsize) {
 		note_map_len = round_page(phdr->p_offset +
 		  phdr->p_filesz) - trunc_page(phdr->p_offset);
 		note_map = mmap(NULL, note_map_len, PROT_READ,
@@ -315,7 +317,7 @@
 	digest_notes(obj, note_start, note_end);
     if (note_map != NULL)
 	munmap(note_map, note_map_len);
-    munmap(hdr, PAGE_SIZE);
+    free(hdr);
     return (obj);
 
 error1:
@@ -323,26 +325,37 @@
 error:
     if (note_map != NULL && note_map != MAP_FAILED)
 	munmap(note_map, note_map_len);
-    munmap(hdr, PAGE_SIZE);
+    free(hdr);
     return (NULL);
 }
 
-static Elf_Ehdr *
-get_elf_header(int fd, const char *path, const struct stat *sbp)
+static int
+get_elf_header(int fd, const char *path, Elf_Ehdr **hdrp, size_t *hdrsizep)
 {
 	Elf_Ehdr *hdr;
+	size_t hdrsize;
+	ssize_t retval;
 
-	/* Make sure file has enough data for the ELF header */
-	if (sbp != NULL && sbp->st_size < sizeof(Elf_Ehdr)) {
-		_rtld_error("%s: invalid file format", path);
-		return (NULL);
-	}
+	hdr = xmalloc(PAGE_SIZE);
 
-	hdr = mmap(NULL, PAGE_SIZE, PROT_READ, MAP_PRIVATE | MAP_PREFAULT_READ,
-	    fd, 0);
-	if (hdr == (Elf_Ehdr *)MAP_FAILED) {
-		_rtld_error("%s: read error: %s", path, rtld_strerror(errno));
-		return (NULL);
+	/*
+	 * The value "14" was chosen rather arbitrarily, to (almost)
+	 * match GNU/libc, which just hardcodes buffer size of 832.
+	 */
+	hdrsize = sizeof(Elf_Ehdr) + sizeof(Elf_Phdr) * 14;
+
+	retval = pread(fd, hdr, hdrsize, 0);
+	if (retval != hdrsize) {
+		if (retval < 0) {
+			_rtld_error("%s: read error: %s",
+			    path, rtld_strerror(errno));
+			goto error;
+		}
+		if (retval < sizeof(Elf_Ehdr)) {
+			_rtld_error("%s: invalid file format", path);
+			goto error;
+		}
+		hdrsize = retval;
 	}
 
 	/* Make sure the file is valid */
@@ -384,11 +397,26 @@
 		_rtld_error("%s: program header too large", path);
 		goto error;
 	}
-	return (hdr);
+	if (hdr->e_phoff + hdr->e_phnum * sizeof(Elf_Phdr) > hdrsize) {
+		retval = pread(fd, (char *)hdr + hdrsize,
+		    PAGE_SIZE - hdrsize, hdrsize);
+		if (retval != PAGE_SIZE - hdrsize) {
+			if (retval < 0) {
+				_rtld_error("%s: read error: %s",
+				    path, rtld_strerror(errno));
+				goto error;
+			}
+		}
+		hdrsize += retval;
+	}
 
+	*hdrp = hdr;
+	*hdrsizep = hdrsize;
+	return (0);
+
 error:
-	munmap(hdr, PAGE_SIZE);
-	return (NULL);
+	free(hdr);
+	return (-1);
 }
 
 void