From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
Randy Dunlap <rdunlap@infradead.org>,
Borislav Petkov <bp@suse.de>, Kees Cook <keescook@chromium.org>,
Miroslav Benes <mbenes@suse.cz>,
Peter Zijlstra <peterz@infradead.org>,
Sasha Levin <sashal@kernel.org>
Subject: [PATCH AUTOSEL 5.6 19/38] objtool: Fix CONFIG_UBSAN_TRAP unreachable warnings
Date: Fri, 24 Apr 2020 08:22:17 -0400 [thread overview]
Message-ID: <20200424122237.9831-19-sashal@kernel.org> (raw)
In-Reply-To: <20200424122237.9831-1-sashal@kernel.org>
From: Josh Poimboeuf <jpoimboe@redhat.com>
[ Upstream commit bd841d6154f5f41f8a32d3c1b0bc229e326e640a ]
CONFIG_UBSAN_TRAP causes GCC to emit a UD2 whenever it encounters an
unreachable code path. This includes __builtin_unreachable(). Because
the BUG() macro uses __builtin_unreachable() after it emits its own UD2,
this results in a double UD2. In this case objtool rightfully detects
that the second UD2 is unreachable:
init/main.o: warning: objtool: repair_env_string()+0x1c8: unreachable instruction
We weren't able to figure out a way to get rid of the double UD2s, so
just silence the warning.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/6653ad73c6b59c049211bd7c11ed3809c20ee9f5.1585761021.git.jpoimboe@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/objtool/check.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 2b765bbbef922..95c485d3d4d83 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2307,14 +2307,27 @@ static bool ignore_unreachable_insn(struct instruction *insn)
!strcmp(insn->sec->name, ".altinstr_aux"))
return true;
+ if (!insn->func)
+ return false;
+
+ /*
+ * CONFIG_UBSAN_TRAP inserts a UD2 when it sees
+ * __builtin_unreachable(). The BUG() macro has an unreachable() after
+ * the UD2, which causes GCC's undefined trap logic to emit another UD2
+ * (or occasionally a JMP to UD2).
+ */
+ if (list_prev_entry(insn, list)->dead_end &&
+ (insn->type == INSN_BUG ||
+ (insn->type == INSN_JUMP_UNCONDITIONAL &&
+ insn->jump_dest && insn->jump_dest->type == INSN_BUG)))
+ return true;
+
/*
* Check if this (or a subsequent) instruction is related to
* CONFIG_UBSAN or CONFIG_KASAN.
*
* End the search at 5 instructions to avoid going into the weeds.
*/
- if (!insn->func)
- return false;
for (i = 0; i < 5; i++) {
if (is_kasan_insn(insn) || is_ubsan_insn(insn))
--
2.20.1
next prev parent reply other threads:[~2020-04-24 12:32 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-24 12:21 [PATCH AUTOSEL 5.6 01/38] libbpf: Initialize *nl_pid so gcc 10 is happy Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 02/38] net: fec: set GPR bit on suspend by DT configuration Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 03/38] x86: hyperv: report value of misc_features Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 04/38] signal: check sig before setting info in kill_pid_usb_asyncio Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 05/38] hwmon: (drivetemp) Use drivetemp's true module name in Kconfig section Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 06/38] hwmon: (drivetemp) Return -ENODATA for invalid temperatures Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 07/38] afs: Fix length of dump of bad YFSFetchStatus record Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 08/38] xfs: acquire superblock freeze protection on eofblocks scans Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 09/38] xfs: fix partially uninitialized structure in xfs_reflink_remap_extent Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 10/38] ALSA: hda: Release resources at error in delayed probe Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 11/38] ALSA: hda: Keep the controller initialization even if no codecs found Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 12/38] ALSA: hda: Skip controller resume if not needed Sasha Levin
2020-04-24 12:44 ` Takashi Iwai
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 13/38] ALSA: hda: Explicitly permit using autosuspend if runtime PM is supported Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 14/38] drm/amdgpu: fix wrong vram lost counter increment V2 Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 15/38] scsi: target: fix PR IN / READ FULL STATUS for FC Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 16/38] scsi: target: tcmu: reset_ring should reset TCMU_DEV_BIT_BROKEN Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 17/38] clk: asm9260: fix __clk_hw_register_fixed_rate_with_accuracy typo Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 18/38] efi/x86: Don't remap text<->rodata gap read-only for mixed mode Sasha Levin
2020-04-24 12:22 ` Sasha Levin [this message]
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 20/38] objtool: Support Clang non-section symbols in ORC dump Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 21/38] xen/xenbus: ensure xenbus_map_ring_valloc() returns proper grant status Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 22/38] ALSA: hda: call runtime_allow() for all hda controllers Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 23/38] net: stmmac: socfpga: Allow all RGMII modes Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 24/38] net/cxgb4: Check the return from t4_query_params properly Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 25/38] mac80211: fix channel switch trigger from unknown mesh peer Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 26/38] sched/isolation: Allow "isolcpus=" to skip unknown sub-parameters Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 27/38] sched/vtime: Work around an unitialized variable warning Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 28/38] i2c: remove i2c_new_probed_device API Sasha Levin
2020-04-24 13:36 ` Wolfram Sang
2020-04-25 1:51 ` Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 29/38] arm64: Delete the space separator in __emit_inst Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 30/38] i2c: tegra: Better handle case where CPU0 is busy for a long time Sasha Levin
2020-04-27 7:22 ` Thierry Reding
2020-05-01 0:59 ` Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 31/38] i2c: tegra: Synchronize DMA before termination Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 32/38] ext4: use matching invalidatepage in ext4_writepage Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 33/38] ext4: increase wait time needed before reuse of deleted inode numbers Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 34/38] ext4: convert BUG_ON's to WARN_ON's in mballoc.c Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 35/38] irqchip/gic-v4.1: Add support for VPENDBASER's Dirty+Valid signaling Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 36/38] blk-mq: Put driver tag in blk_mq_dispatch_rq_list() when no budget Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 37/38] irqchip/meson-gpio: Fix HARDIRQ-safe -> HARDIRQ-unsafe lock order Sasha Levin
2020-04-24 12:22 ` [PATCH AUTOSEL 5.6 38/38] hwmon: (jc42) Fix name to have no illegal characters Sasha Levin
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