fix divide by zero in old glibc dynamic loader

R=r
CC=iant
http://go/go-review/1018024

diff --git a/src/cmd/8l/asm.c b/src/cmd/8l/asm.c
index 559d816bd7017ce3423a017c8421bbbc21d94a9c..6dfdc387a869ca66fa1045bfd91b45b518a03b91 100644 (file)
--- a/src/cmd/8l/asm.c
+++ b/src/cmd/8l/asm.c
@@ -307,14 +307,21 @@ doelf(void)
 
                /*
                 * hash table - empty for now.
-                * we should have to fill it out with an entry for every
-                * symbol in .dynsym, but it seems to work not to,
-                * which is fine with me.
+                * only entries that other objects need to find when
+                * linking us need to be in this table.  right now that
+                * is no entries.
+                *
+                * must have at least 1 bucket, though, to avoid
+                * a divide by zero bug in some copies of the
+                * glibc dynamic loader.
                 */
                s = lookup(".hash", 0);
                s->type = SDATA;        // TODO: rodata
                s->reachable = 1;
-               s->value += 8;  // two leading zeros
+               adduint32(s, 1);        // nbucket
+               adduint32(s, 1);        // nchain
+               adduint32(s, 0);        // bucket[0]
+               adduint32(s, 0);        // chain[0]
 
                /* dynamic symbol table - first entry all zeros */
                s = lookup(".dynsym", 0);