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Message-ID: <20211202204534.GA16608@worktop.programming.kicks-ass.net>
Date: Thu, 2 Dec 2021 21:45:34 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Josh Poimboeuf <jpoimboe@...hat.com>, x86@...nel.org
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH] objtool: Fix pv_ops noinstr validation
Boris reported that in one of this randconfig builds, objtool got
infinitely stuck. Turns out there's trivial list corruption in the
pv_ops tracking when a function is both in a static table and in a
code assignment.
Avoid re-adding function to the pv_ops[] lists when they're already on
it.
Fixes: db2b0c5d7b6f ("objtool: Support pv_opsindirect calls for noinstr")
Reported-by: Borislav Petkov <bp@...en8.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Tested-by: Borislav Petkov <bp@...en8.de>
---
tools/objtool/elf.c | 1 +
tools/objtool/objtool.c | 4 ++++
2 files changed, 5 insertions(+)
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -375,6 +375,7 @@ static int read_symbols(struct elf *elf)
return -1;
}
memset(sym, 0, sizeof(*sym));
+ INIT_LIST_HEAD(&sym->pv_target);
sym->alias = sym;
sym->idx = i;
--- a/tools/objtool/objtool.c
+++ b/tools/objtool/objtool.c
@@ -153,6 +153,10 @@ void objtool_pv_add(struct objtool_file
!strcmp(func->name, "_paravirt_ident_64"))
return;
+ /* already added this function */
+ if (!list_empty(&func->pv_target))
+ return;
+
list_add(&func->pv_target, &f->pv_ops[idx].targets);
f->pv_ops[idx].clean = false;
}
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