From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Andrew Cooper <andrew.cooper3@citrix.com>,
Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Borislav Petkov <bp@suse.de>,
Daniel Sneddon <daniel.sneddon@linux.intel.com>
Subject: [PATCH 5.18 35/35] x86/speculation: Add LFENCE to RSB fill sequence
Date: Tue, 9 Aug 2022 20:01:04 +0200 [thread overview]
Message-ID: <20220809175516.425509841@linuxfoundation.org> (raw)
In-Reply-To: <20220809175515.046484486@linuxfoundation.org>
From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
commit ba6e31af2be96c4d0536f2152ed6f7b6c11bca47 upstream.
RSB fill sequence does not have any protection for miss-prediction of
conditional branch at the end of the sequence. CPU can speculatively
execute code immediately after the sequence, while RSB filling hasn't
completed yet.
#define __FILL_RETURN_BUFFER(reg, nr, sp) \
mov $(nr/2), reg; \
771: \
ANNOTATE_INTRA_FUNCTION_CALL; \
call 772f; \
773: /* speculation trap */ \
UNWIND_HINT_EMPTY; \
pause; \
lfence; \
jmp 773b; \
772: \
ANNOTATE_INTRA_FUNCTION_CALL; \
call 774f; \
775: /* speculation trap */ \
UNWIND_HINT_EMPTY; \
pause; \
lfence; \
jmp 775b; \
774: \
add $(BITS_PER_LONG/8) * 2, sp; \
dec reg; \
jnz 771b; <----- CPU can miss-predict here.
Before RSB is filled, RETs that come in program order after this macro
can be executed speculatively, making them vulnerable to RSB-based
attacks.
Mitigate it by adding an LFENCE after the conditional branch to prevent
speculation while RSB is being filled.
Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/include/asm/nospec-branch.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -60,7 +60,9 @@
774: \
add $(BITS_PER_LONG/8) * 2, sp; \
dec reg; \
- jnz 771b;
+ jnz 771b; \
+ /* barrier for jnz misprediction */ \
+ lfence;
#ifdef __ASSEMBLY__
next prev parent reply other threads:[~2022-08-09 18:29 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-09 18:00 [PATCH 5.18 00/35] 5.18.17-rc1 review Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 01/35] x86/speculation: Make all RETbleed mitigations 64-bit only Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 02/35] block: fix default IO priority handling again Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 03/35] tools/vm/slabinfo: Handle files in debugfs Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 04/35] ACPI: video: Force backlight native for some TongFang devices Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 05/35] ACPI: video: Shortening quirk list by identifying Clevo by board_name only Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 06/35] ACPI: APEI: Better fix to avoid spamming the console with old error logs Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 07/35] crypto: arm64/poly1305 - fix a read out-of-bound Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 08/35] KVM: x86: do not report a vCPU as preempted outside instruction boundaries Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 09/35] KVM: x86: do not set st->preempted when going back to user space Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 10/35] KVM: selftests: Make hyperv_clock selftest more stable Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 11/35] KVM: x86/MMU: Zap non-leaf SPTEs when disabling dirty logging Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 12/35] entry/kvm: Exit to user mode when TIF_NOTIFY_SIGNAL is set Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 13/35] KVM: x86: disable preemption while updating apicv inhibition Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 14/35] KVM: x86: disable preemption around the call to kvm_arch_vcpu_{un|}blocking Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 15/35] KVM: selftests: Restrict test region to 48-bit physical addresses when using nested Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 16/35] tools/kvm_stat: fix display of error when multiple processes are found Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 17/35] selftests: KVM: Handle compiler optimizations in ucall Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 18/35] KVM: x86/svm: add __GFP_ACCOUNT to __sev_dbg_{en,de}crypt_user() Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 19/35] arm64: set UXN on swapper page tables Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 20/35] btrfs: zoned: prevent allocation from previous data relocation BG Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 21/35] btrfs: zoned: fix critical section of relocation inode writeback Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 22/35] btrfs: zoned: drop optimization of zone finish Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 23/35] Bluetooth: hci_qca: Return wakeup for qca_wakeup Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 24/35] Bluetooth: hci_bcm: Add BCM4349B1 variant Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 25/35] Bluetooth: hci_bcm: Add DT compatible for CYW55572 Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 26/35] dt-bindings: bluetooth: broadcom: Add BCM4349B1 DT binding Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 27/35] Bluetooth: btusb: Add support of IMC Networks PID 0x3568 Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 28/35] Bluetooth: btusb: Add Realtek RTL8852C support ID 0x04CA:0x4007 Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 29/35] Bluetooth: btusb: Add Realtek RTL8852C support ID 0x04C5:0x1675 Greg Kroah-Hartman
2022-08-09 18:00 ` [PATCH 5.18 30/35] Bluetooth: btusb: Add Realtek RTL8852C support ID 0x0CB8:0xC558 Greg Kroah-Hartman
2022-08-09 18:01 ` [PATCH 5.18 31/35] Bluetooth: btusb: Add Realtek RTL8852C support ID 0x13D3:0x3587 Greg Kroah-Hartman
2022-08-09 18:01 ` [PATCH 5.18 32/35] Bluetooth: btusb: Add Realtek RTL8852C support ID 0x13D3:0x3586 Greg Kroah-Hartman
2022-08-09 18:01 ` [PATCH 5.18 33/35] macintosh/adb: fix oob read in do_adb_query() function Greg Kroah-Hartman
2022-08-09 18:01 ` [PATCH 5.18 34/35] x86/speculation: Add RSB VM Exit protections Greg Kroah-Hartman
2022-08-09 18:01 ` Greg Kroah-Hartman [this message]
2022-08-09 21:47 ` [PATCH 5.18 00/35] 5.18.17-rc1 review Florian Fainelli
2022-08-10 6:16 ` Naresh Kamboju
2022-08-10 12:54 ` Ron Economos
2022-08-10 13:26 ` Sudip Mukherjee (Codethink)
2022-08-10 13:33 ` Guenter Roeck
2022-08-10 14:17 ` Justin Forbes
2022-08-10 14:31 ` Shuah Khan
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