linux-kernel - [PATCH v3 1/2] objtool: fix failed cold symbol doublefree

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Date:   Mon, 12 Nov 2018 13:55:18 +0100
From:   Artem Savkov <asavkov@...hat.com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        linux-kernel@...r.kernel.org, Artem Savkov <asavkov@...hat.com>
Subject: [PATCH v3 1/2] objtool: fix failed cold symbol doublefree

If read_symbols() fails during second list traversal (the one dealing
with ".cold" subfunctions) it frees the symbol, but never deletes it
from the list/hash_table resulting in symbol being freed again in
elf_close().

Fixes: 13810435b9a7 "objtool: Support GCC 8's cold subfunctions"
Signed-off-by: Artem Savkov <asavkov@...hat.com>
---
 tools/objtool/elf.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 6dbb9fae0f9d..3decd43477df 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -312,7 +312,7 @@ static int read_symbols(struct elf *elf)
 			if (!pfunc) {
 				WARN("%s(): can't find parent function",
 				     sym->name);
-				goto err;
+				goto cold_err;
 			}
 
 			sym->pfunc = pfunc;
@@ -336,6 +336,9 @@ static int read_symbols(struct elf *elf)
 
 	return 0;
 
+cold_err:
+	list_del(&sym->list);
+	hash_del(&sym->hash);
 err:
 	free(sym);
 	return -1;
-- 
2.17.2