From 69f361b8a7a2f65c1bb236ea0899cdaad7267653 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Fri, 7 Aug 2026 14:37:49 -0700 Subject: [PATCH] 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 Acked-by: Song Liu Link: https://patch.msgid.link/516e14f84cfbffa27dc19d3dcf35097504097966.1786138493.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf --- 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 bbfae516d339..dfca9dd74681 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;