git: 5e4279a8f35a - main - loader: fix multiboot loading on UEFI

[Roger Pau Monné]

The branch main has been updated by royger:

URL: https://cgit.FreeBSD.org/src/commit/?id=5e4279a8f35aa4b46debf728d3f743d64f15aaf8

commit 5e4279a8f35aa4b46debf728d3f743d64f15aaf8
Author:     Roger Pau Monné <royger at FreeBSD.org>
AuthorDate: 2021-08-11 14:55:10 +0000
Commit:     Roger Pau Monné <royger at FreeBSD.org>
CommitDate: 2021-08-12 07:18:33 +0000

    loader: fix multiboot loading on UEFI
    
    The Xen kernel has no symbol tables, so calling lookup_symbol against
    it triggers the following Divide by Zero fault:
    
    Loading Xen kernel...
    /boot/xen data=0x2809c8+0x149638 |
    !!!! X64 Exception Type - 00(#DE - Divide Error)  CPU Apic ID - 00000000 !!!!
    
    Fix lookup_symbol to prevent the #DE fault from happening if the
    symbol table is not loaded and also fix loadfile_raw to mark multiboot
    kernels as relocatable, since the only multiboot kernel supported is
    Xen and was already unconditionally booted as relocatable.
    
    Fixes: f75caed644a5 ('amd64 UEFI loader: stop copying staging area to 2M physical')
    Reviewed by: imp, kib
    Differential Revision: https://reviews.freebsd.org/D31507
---
 stand/common/load_elf.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/stand/common/load_elf.c b/stand/common/load_elf.c
index 9ae91036dbb4..c163b50c9737 100644
--- a/stand/common/load_elf.c
+++ b/stand/common/load_elf.c
@@ -447,7 +447,7 @@ __elfN(loadfile_raw)(char *filename, uint64_t dest,
 	*result = (struct preloaded_file *)fp;
 	err = 0;
 #ifdef __amd64__
-	fp->f_kernphys_relocatable = is_kernphys_relocatable(&ef);
+	fp->f_kernphys_relocatable = multiboot || is_kernphys_relocatable(&ef);
 #endif
 	goto out;
 
@@ -1253,6 +1253,11 @@ __elfN(lookup_symbol)(elf_file_t ef, const char* name, Elf_Sym *symp,
 	char *strp;
 	unsigned long hash;
 
+	if (ef->nbuckets == 0) {
+		printf(__elfN(bad_symtable));
+		return ENOENT;
+	}
+
 	hash = elf_hash(name);
 	COPYOUT(&ef->buckets[hash % ef->nbuckets], &symnum, sizeof(symnum));