Fix incorrect reading of 32-bit modinfo by 64-bit loaders.

The various structures in the mod_metadata set of a FreeBSD kernel and
modules contain pointers. The FreeBSD loader correctly deals with a
mismatch in loader and kernel pointer size (e.g. 32-bit i386/ppc
loader, loading 64-bit amd64/ppc64 kernels), but wasn't dealing with
the inverse case where a 64-bit loader was loading a 32-bit kernel.

Reported by:	ktcallbox@gmail.com with a bhyve/i386 and ZFS root install
Differential Revision:	https://reviews.freebsd.org/D1129
Reviewed by:	neel, jhb
MFC after:	1 week

1 files changed, 22 insertions, 0 deletions

diff --git a/sys/boot/common/load_elf.c b/sys/boot/common/load_elf.c
index 04a7dbe..62ae747 100644
--- a/sys/boot/common/load_elf.c
+++ b/sys/boot/common/load_elf.c
@@ -640,6 +640,14 @@ struct mod_metadata64 {
 	u_int64_t	md_cval;	/* common string label */
 };
 #endif
+#if defined(__amd64__) && __ELF_WORD_SIZE == 32
+struct mod_metadata32 {
+	int		md_version;	/* structure version MDTV_* */  
+	int		md_type;	/* type of entry MDT_* */
+	u_int32_t	md_data;	/* specific data */
+	u_int32_t	md_cval;	/* common string label */
+};
+#endif
 
 int
 __elfN(parse_modmetadata)(struct preloaded_file *fp, elf_file_t ef)
@@ -647,6 +655,8 @@ __elfN(parse_modmetadata)(struct preloaded_file *fp, elf_file_t ef)
     struct mod_metadata md;
 #if (defined(__i386__) || defined(__powerpc__)) && __ELF_WORD_SIZE == 64
     struct mod_metadata64 md64;
+#elif defined(__amd64__) && __ELF_WORD_SIZE == 32
+    struct mod_metadata32 md32;
 #endif
     struct mod_depend *mdepend;
     struct mod_version mver;
@@ -682,6 +692,18 @@ __elfN(parse_modmetadata)(struct preloaded_file *fp, elf_file_t ef)
 	md.md_type = md64.md_type;
 	md.md_cval = (const char *)(uintptr_t)md64.md_cval;
 	md.md_data = (void *)(uintptr_t)md64.md_data;
+#elif defined(__amd64__) && __ELF_WORD_SIZE == 32
+	COPYOUT(v, &md32, sizeof(md32));
+	error = __elfN(reloc_ptr)(fp, ef, v, &md32, sizeof(md32));
+	if (error == EOPNOTSUPP) {
+	    md32.md_cval += ef->off;
+	    md32.md_data += ef->off;
+	} else if (error != 0)
+	    return (error);
+	md.md_version = md32.md_version;
+	md.md_type = md32.md_type;
+	md.md_cval = (const char *)(uintptr_t)md32.md_cval;
+	md.md_data = (void *)(uintptr_t)md32.md_data;
 #else
 	COPYOUT(v, &md, sizeof(md));
 	error = __elfN(reloc_ptr)(fp, ef, v, &md, sizeof(md));