[tip: objtool/core] objtool/klp: Explicitly disallow patching or referencing init code/data

[tip-bot2 for Josh Poimboeuf]

The following commit has been merged into the objtool/core branch of tip:

Commit-ID:     69f361b8a7a2f65c1bb236ea0899cdaad7267653
Gitweb:        https://git.kernel.org/tip/69f361b8a7a2f65c1bb236ea0899cdaad7267653
Author:        Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
AuthorDate:    Fri, 07 Aug 2026 14:37:49 -07:00
Committer:     Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
CommitterDate: Tue, 11 Aug 2026 16:10:38 -07:00

objtool/klp: Explicitly disallow patching or referencing init code/data

Explicitly disallow the patching and referencing of init code/data.
Otherwise it could potentially introduce some odd edge cases depending
on whether the target object's init section has been freed yet (note
that the init code still exists in the target module when doing late
module patching).

Such edge cases include sympos calculation and the patching and/or
referencing of non-existent (init-freed) code/data.  Not to mention the
inherent differences in behavior that occur when the init code is only
patched *some* of the time depending on module loading order or kernel
config.

Acked-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
Acked-by: Song Liu <song@xxxxxxxxxx>
Link: https://patch.msgid.link/516e14f84cfbffa27dc19d3dcf35097504097966.1786138493.git.jpoimboe@xxxxxxxxxx
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
---
 tools/objtool/klp-sympos.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tools/objtool/klp-sympos.c b/tools/objtool/klp-sympos.c
index bbfae51..dfca9dd 100644
--- a/tools/objtool/klp-sympos.c
+++ b/tools/objtool/klp-sympos.c
@@ -367,6 +367,11 @@ static unsigned long find_vmlinux_sympos(struct symbol *sym)
 	return sympos;
 }
 
+static bool is_init_sym(struct symbol *sym)
+{
+	return strstarts(sym->sec->name, ".init");
+}
+
 /*
  * "sympos" is used by livepatch to disambiguate duplicate symbol names.
  */
@@ -376,6 +381,11 @@ unsigned long klp_find_sympos(struct elf *elf, struct symbol *sym)
 	bool has_dup = false;
 	struct symbol *s;
 
+	if (is_init_sym(sym)) {
+		ERROR("%s: can't patch or reference init code/data", sym->name);
+		return ULONG_MAX;
+	}
+
 	if (sym->bind != STB_LOCAL)
 		return 0;