modpost: fix inverted logic in is_extable_fault_address().

As Guenter pointed out, we want to assert that extable_entry_size has been discovered and not the other way around. Moreover, this sanity check is only valid when we're not dealing with the first relocation in __ex_table, since we have not discovered the extable entry size at that point. This was leading to a divide-by-zero on some architectures and make the build fail. Signed-off-by: Quentin Casasnovas <[email protected]> Reported-by: Guenter Roeck <[email protected]> CC: Rusty Russell <[email protected]> Signed-off-by: Rusty Russell <[email protected]>
TechNexion · Apr 22, 2015 · d3df4de · d3df4de
1 parent 6c730bf
commit d3df4de
Showing 1 changed file with 6 additions and 1 deletion.
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
@@ -1529,7 +1529,12 @@ static void find_extable_entry_size(const char* const sec, const Elf_Rela* r,
 }
 static inline bool is_extable_fault_address(Elf_Rela *r)
 {
-	if (!extable_entry_size == 0)
+	/*
+	 * extable_entry_size is only discovered after we've handled the
+	 * _second_ relocation in __ex_table, so only abort when we're not
+	 * handling the first reloc and extable_entry_size is zero.
+	 */
+	if (r->r_offset && extable_entry_size == 0)
 		fatal("extable_entry size hasn't been discovered!\n");
 
 	return ((r->r_offset == 0) ||