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From: Josh Poimboeuf <jpoimboe@redhat.com>
To: x86@kernel.org
Cc: linux-kernel@vger.kernel.org,
	Peter Zijlstra <peterz@infradead.org>,
	Sami Tolvanen <samitolvanen@google.com>,
	Sedat Dilek <sedat.dilek@gmail.com>,
	Kees Cook <keescook@chromium.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	clang-built-linux@googlegroups.com,
	Miroslav Benes <mbenes@suse.cz>
Subject: [PATCH 01/21] objtool: Fix seg fault in BT_FUNC() with fake jump
Date: Thu, 14 Jan 2021 13:39:57 -0600	[thread overview]
Message-ID: <c6bd154e55739c332c21ca4a91a66787cc3e104c.1610652862.git.jpoimboe@redhat.com> (raw)
In-Reply-To: <cover.1610652862.git.jpoimboe@redhat.com>

Objtool appends a temporary fake jump at the end of alternative
replacement instructions.  If the replacement code is empty -- resulting
in patched nops -- the fake jump doesn't have a section.  When running
objtool with '--backtrace', the fake jump's missing section can cause
BT_FUNC() to trigger a seg fault when the NULL insn->sec is passed to
offstr().

Fix it by ensuring fake jumps always have a section.

Fixes: 7697eee3ddd7 ("objtool: Add --backtrace support")
Reported-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
 tools/objtool/check.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 5f8d3eed78a1..ed26c22c8244 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1017,7 +1017,7 @@ static int handle_group_alt(struct objtool_file *file,
 		INIT_LIST_HEAD(&fake_jump->stack_ops);
 		init_cfi_state(&fake_jump->cfi);
 
-		fake_jump->sec = special_alt->new_sec;
+		fake_jump->sec = special_alt->new_sec ? : orig_insn->sec;
 		fake_jump->offset = FAKE_JUMP_OFFSET;
 		fake_jump->type = INSN_JUMP_UNCONDITIONAL;
 		fake_jump->jump_dest = list_next_entry(last_orig_insn, list);
-- 
2.29.2


  reply	other threads:[~2021-01-14 19:42 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-14 19:39 [PATCH 00/21] objtool: vmlinux.o and CLANG LTO support Josh Poimboeuf
2021-01-14 19:39 ` Josh Poimboeuf [this message]
2021-01-14 20:04   ` [PATCH 01/21] objtool: Fix seg fault in BT_FUNC() with fake jump Josh Poimboeuf
2021-01-14 19:39 ` [PATCH 02/21] objtool: Fix error handling for STD/CLD warnings Josh Poimboeuf
2021-01-14 19:39 ` [PATCH 03/21] objtool: Fix retpoline detection in asm code Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 04/21] objtool: Fix ".cold" section suffix check for newer versions of GCC Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 05/21] objtool: Support retpoline jump detection for vmlinux.o Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 06/21] x86/ftrace: Add UNWIND_HINT_FUNC annotation for ftrace_stub Josh Poimboeuf
2021-01-14 20:42   ` Steven Rostedt
2021-01-14 19:40 ` [PATCH 07/21] objtool: Assume only ELF functions do sibling calls Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 08/21] objtool: Add asm version of STACK_FRAME_NON_STANDARD Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 09/21] objtool: Combine UNWIND_HINT_RET_OFFSET and UNWIND_HINT_FUNC Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 10/21] objtool: Add xen_start_kernel() to noreturn list Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 11/21] objtool: Move unsuffixed symbol conversion to a helper function Josh Poimboeuf
2021-01-14 20:55   ` [PATCH v1.1 " Josh Poimboeuf
2021-01-14 21:30     ` Sedat Dilek
2021-01-14 19:40 ` [PATCH 12/21] objtool: Add CONFIG_CFI_CLANG support Josh Poimboeuf
2021-01-14 20:49   ` Sami Tolvanen
2021-01-14 20:52     ` Josh Poimboeuf
2021-01-14 20:56   ` [PATCH v1.1 " Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 13/21] x86/xen: Support objtool validation in xen-asm.S Josh Poimboeuf
2021-01-15  0:31   ` boris.ostrovsky
2021-01-14 19:40 ` [PATCH 14/21] x86/xen: Support objtool vmlinux.o validation in xen-head.S Josh Poimboeuf
2021-01-15  0:32   ` boris.ostrovsky
2021-01-15  5:17   ` Jürgen Groß
2021-01-15 19:46     ` Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 15/21] x86/xen/pvh: Convert indirect jump to retpoline Josh Poimboeuf
2021-01-15  0:33   ` boris.ostrovsky
2021-01-15  5:24   ` Jürgen Groß
2021-01-15 15:08     ` Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 16/21] x86/ftrace: Support objtool vmlinux.o validation in ftrace_64.S Josh Poimboeuf
2021-01-14 20:42   ` Steven Rostedt
2021-01-14 19:40 ` [PATCH 17/21] x86/acpi: Convert indirect jump to retpoline Josh Poimboeuf
2021-01-14 22:59   ` Andrew Cooper
2021-01-14 23:47     ` Josh Poimboeuf
2021-01-15  0:54       ` Andrew Cooper
2021-01-14 19:40 ` [PATCH 18/21] x86/acpi: Support objtool validation in wakeup_64.S Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 19/21] x86/power: Convert indirect jumps to retpolines Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 20/21] x86/power: Move restore_registers() to top of the file Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 21/21] x86/power: Support objtool validation in hibernate_asm_64.S Josh Poimboeuf
2021-01-15  0:41 ` [PATCH 00/21] objtool: vmlinux.o and CLANG LTO support Sami Tolvanen
2021-01-15  0:49   ` Nick Desaulniers
2021-01-15 19:52   ` Josh Poimboeuf
2021-01-15 20:19     ` Sedat Dilek
2021-01-15 20:59       ` Josh Poimboeuf
2021-01-15 21:01         ` Sedat Dilek
2021-01-18 17:22   ` Josh Poimboeuf
2021-01-19 21:29     ` Nick Desaulniers
2021-01-20 15:37       ` Josh Poimboeuf
2021-01-15  4:51 ` Sedat Dilek
2021-01-15  5:18   ` Sedat Dilek
2021-01-15 15:30   ` Sedat Dilek
2021-01-15 18:54     ` Sedat Dilek
2021-01-15 19:28       ` Josh Poimboeuf

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