linux-kernel - [PATCH v2 13/62] objtool: Fix broken error handling in read

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Message-ID: <16c0fcf02cdce0b93666e853070086d5e40be0e6.1746821544.git.jpoimboe@kernel.org>
Date: Fri,  9 May 2025 13:16:37 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
	Petr Mladek <pmladek@...e.com>,
	Miroslav Benes <mbenes@...e.cz>,
	Joe Lawrence <joe.lawrence@...hat.com>,
	live-patching@...r.kernel.org,
	Song Liu <song@...nel.org>,
	laokz <laokz@...mail.com>,
	Jiri Kosina <jikos@...nel.org>,
	Marcos Paulo de Souza <mpdesouza@...e.com>,
	Weinan Liu <wnliu@...gle.com>,
	Fazla Mehrab <a.mehrab@...edance.com>,
	Chen Zhongjin <chenzhongjin@...wei.com>,
	Puranjay Mohan <puranjay@...nel.org>
Subject: [PATCH v2 13/62] objtool: Fix broken error handling in read_symbols()

The free(sym) call in the read_symbols() error path is fundamentally
broken: 'sym' doesn't point to any allocated block.  If triggered,
things would go from bad to worse.

Remove the free() and simplify the error paths.  Freeing memory isn't
necessary here anyway, these are fatal errors which lead to an immediate
exit().

Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 tools/objtool/elf.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 1c1bb2cb960d..b009d9feed76 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -492,14 +492,14 @@ static int read_symbols(struct elf *elf)
 		if (!gelf_getsymshndx(symtab->data, shndx_data, i, &sym->sym,
 				      &shndx)) {
 			ERROR_ELF("gelf_getsymshndx");
-			goto err;
+			return -1;
 		}
 
 		sym->name = elf_strptr(elf->elf, symtab->sh.sh_link,
 				       sym->sym.st_name);
 		if (!sym->name) {
 			ERROR_ELF("elf_strptr");
-			goto err;
+			return -1;
 		}
 
 		if ((sym->sym.st_shndx > SHN_UNDEF &&
@@ -511,7 +511,7 @@ static int read_symbols(struct elf *elf)
 			sym->sec = find_section_by_index(elf, shndx);
 			if (!sym->sec) {
 				ERROR("couldn't find section for symbol %s", sym->name);
-				goto err;
+				return -1;
 			}
 			if (GELF_ST_TYPE(sym->sym.st_info) == STT_SECTION) {
 				sym->name = sym->sec->name;
@@ -581,10 +581,6 @@ static int read_symbols(struct elf *elf)
 	}
 
 	return 0;
-
-err:
-	free(sym);
-	return -1;
 }
 
 static int mark_group_syms(struct elf *elf)
-- 
2.49.0