objtool: skip non-text sections when adding return-thunk sites

stable inclusion
from stable-v5.10.133
commit 446eb6f08936e6f87bea9f35be05556a7211df9b
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5PTAS
CVE: CVE-2022-29900,CVE-2022-23816,CVE-2022-29901

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=446eb6f08936e6f87bea9f35be05556a7211df9b

--------------------------------

The .discard.text section is added in order to reserve BRK, with a
temporary function just so it can give it a size. This adds a relocation to
the return thunk, which objtool will add to the .return_sites section.
Linking will then fail as there are references to the .discard.text
section.

Do not add instructions from non-text sections to the list of return thunk
calls, avoiding the reference to .discard.text.
Signed-off-by: NThadeu Lima de Souza Cascardo <cascardo@canonical.com>
Acked-by: NJosh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: NBen Hutchings <ben@decadent.org.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NLin Yujun <linyujun809@huawei.com>
Reviewed-by: NZhang Jianhua <chris.zjh@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

tools/objtool/check.c

@@ -1089,7 +1089,9 @@ static void add_return_call(struct objtool_file *file, struct instruction *insn)
 	insn->type = INSN_RETURN;
 	insn->retpoline_safe = true;
 
-	list_add_tail(&insn->call_node, &file->return_thunk_list);
+	/* Skip the non-text sections, specially .discard ones */
+	if (insn->sec->text)
+		list_add_tail(&insn->call_node, &file->return_thunk_list);
 }
 
 /*