April 2023 - Kernel - mailweb.openeuler.org

[PATCH openEuler-1.0-LTS 0/6] efi: fix crash due to EFI runtime service page faults
by Ding Hui 20 Apr '23

20 Apr '23

For both arm64 and x86, handle and recovery from page faults due to EFI runtime service, and disable subsequent invoking, we can avoid crash the whole system when running on buggy EFI firmware, and get log like this: kernel: [Firmware Bug]: Unable to handle paging request in EFI runtime service kernel: CPU: 54 PID: 8 Comm: kworker/u256:0 Kdump: loaded Tainted: G IOE 4.19.90-2112.8.0.0131.oe1.aarch64.debug #66 kernel: Hardware name: O.D.M FT-2500 Platform/T1DMFT-E4 , BIOS KL4.26.ODM.S.032.210904.R 09/04/21 13:28:40 kernel: Workqueue: efi_rts_wq efi_call_rts kernel: Call trace: kernel: dump_backtrace+0x0/0x170 kernel: show_stack+0x24/0x30 kernel: dump_stack+0xa4/0xe8 kernel: efi_runtime_fixup_exception+0x74/0x8c kernel: __do_kernel_fault+0x8c/0x150 kernel: do_page_fault+0x78/0x4c8 kernel: do_translation_fault+0xa8/0xbc kernel: do_mem_abort+0x50/0xe0 kernel: el1_da+0x20/0x94 kernel: 0x213f0c24 kernel: 0x213f0d64 kernel: 0x213f044c kernel: 0x213f04b4 kernel: 0x213f0178 kernel: 0x212e0664 kernel: __efi_rt_asm_wrapper+0x50/0x6c kernel: efi_call_rts+0x414/0x430 kernel: process_one_work+0x1f8/0x490 kernel: worker_thread+0x50/0x4b8 kernel: kthread+0x134/0x138 kernel: ret_from_fork+0x10/0x18 kernel: [Firmware Bug]: Synchronous exception occurred in EFI runtime service get_time() kernel: rtc-efi rtc-efi: can't read time kernel: efi: EFI Runtime Services are disabled! Anders Roxell (1): efi: Fix build error due to enum collision between efi.h and ima.h Ard Biesheuvel (1): arm64: efi: Recover from synchronous exceptions occurring in firmware Sai Praneeth (2): efi: Make efi_rts_work accessible to efi page fault handler efi/x86: Handle page faults occurring while running EFI runtime services Sami Tolvanen (1): arm64: efi: Restore register x18 if it was corrupted Waiman Long (1): efi: Fix debugobjects warning on 'efi_rts_work' arch/arm64/include/asm/efi.h | 9 ++ arch/arm64/kernel/efi-rt-wrapper.S | 46 +++++++++- arch/arm64/kernel/efi.c | 26 ++++++ arch/arm64/mm/fault.c | 4 + arch/x86/include/asm/efi.h | 1 + arch/x86/mm/fault.c | 9 ++ arch/x86/platform/efi/quirks.c | 78 +++++++++++++++++ drivers/firmware/efi/runtime-wrappers.c | 107 +++++++++--------------- include/linux/efi.h | 42 ++++++++++ 9 files changed, 252 insertions(+), 70 deletions(-) -- 2.17.1

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[PATCH openEuler-1.0-LTS] iommu/arm-smmu-v3: Fix UAF when handle evt during iommu group removing
by Ding Hui 20 Apr '23

20 Apr '23

driver inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I6WKM7 CVE: NA -------- A use-after-free issue like following: [ 2257.819189] arm-smmu-v3 arm-smmu-v3.4.auto: EVTQ overflow detected -- events lost [ 2257.819197] arm-smmu-v3 arm-smmu-v3.4.auto: event 0x10 received: [ 2257.819199] arm-smmu-v3 arm-smmu-v3.4.auto: 0x0000820000000010 [ 2257.819201] arm-smmu-v3 arm-smmu-v3.4.auto: 0x0000020000000000 [ 2257.819202] arm-smmu-v3 arm-smmu-v3.4.auto: 0x00000000dfea7218 [ 2257.819206] iommu: Removing device 0000:82:00.0 from group 49 [ 2257.819207] arm-smmu-v3 arm-smmu-v3.4.auto: 0x00000000dfea7000 [ 2257.819211] arm-smmu-v3 arm-smmu-v3.4.auto: event 0x10 received: [ 2257.819212] arm-smmu-v3 arm-smmu-v3.4.auto: 0x0000820000000010 [ 2257.819214] arm-smmu-v3 arm-smmu-v3.4.auto: 0x0000020000000000 [ 2257.819215] arm-smmu-v3 arm-smmu-v3.4.auto: 0x00000000dfea722c [ 2257.819216] arm-smmu-v3 arm-smmu-v3.4.auto: 0x00000000dfea7000 [ 2257.819218] ================================================================== [ 2257.819228] BUG: KASAN: use-after-free in iommu_report_device_fault+0x520/0x5c0 [ 2257.819230] Read of size 8 at addr ffffa02c516c1320 by task irq/63-arm-smmu/483 [ 2257.819231] [ 2257.819235] CPU: 25 PID: 483 Comm: irq/63-arm-smmu Kdump: loaded Tainted: G OE 4.19.90-2205.3.0.0149.oe1.aarch64+debug #1 [ 2257.819236] Hardware name: Huawei S920S00/BC82AMDGK, BIOS 1.68 11/10/2020 [ 2257.819237] Call trace: [ 2257.819240] dump_backtrace+0x0/0x320 [ 2257.819242] show_stack+0x24/0x30 [ 2257.819246] dump_stack+0xdc/0x128 [ 2257.819251] print_address_description+0x68/0x278 [ 2257.819253] kasan_report+0x1e4/0x308 [ 2257.819254] __asan_report_load8_noabort+0x30/0x40 [ 2257.819257] iommu_report_device_fault+0x520/0x5c0 [ 2257.819260] arm_smmu_handle_evt+0x300/0x428 [ 2257.819261] arm_smmu_evtq_thread+0x27c/0x460 [ 2257.819264] irq_thread_fn+0x88/0x140 [ 2257.819266] irq_thread+0x190/0x318 [ 2257.819268] kthread+0x2a4/0x320 [ 2257.819270] ret_from_fork+0x10/0x18 [ 2257.819271] [ 2257.819273] Allocated by task 95166: [ 2257.819275] kasan_kmalloc+0xd0/0x178 [ 2257.819277] kmem_cache_alloc_trace+0x100/0x210 [ 2257.819279] iommu_group_add_device+0x254/0xe18 [ 2257.819280] iommu_group_get_for_dev+0x198/0x480 [ 2257.819282] arm_smmu_add_device+0x424/0x988 [ 2257.819284] iort_iommu_configure+0x33c/0x5b8 [ 2257.819287] acpi_dma_configure+0x9c/0xf8 [ 2257.819289] pci_dma_configure+0x124/0x158 [ 2257.819291] dma_configure+0x5c/0x80 [ 2257.819294] really_probe+0xcc/0x920 [ 2257.819296] driver_probe_device+0x224/0x308 [ 2257.819298] __device_attach_driver+0x154/0x260 [ 2257.819299] bus_for_each_drv+0xe4/0x178 [ 2257.819301] __device_attach+0x1bc/0x2a8 [ 2257.819302] device_attach+0x24/0x30 [ 2257.819304] pci_bus_add_device+0x7c/0xe8 [ 2257.819305] pci_bus_add_devices+0x70/0x168 [ 2257.819307] pci_bus_add_devices+0x114/0x168 [ 2257.819308] pci_rescan_bus+0x38/0x48 [ 2257.819310] bus_rescan_store+0xc4/0xe8 [ 2257.819312] bus_attr_store+0x70/0x98 [ 2257.819314] sysfs_kf_write+0x104/0x170 [ 2257.819316] kernfs_fop_write+0x23c/0x430 [ 2257.819319] __vfs_write+0x7c/0xe8 [ 2257.819320] vfs_write+0x12c/0x3d0 [ 2257.819321] ksys_write+0xd4/0x1d8 [ 2257.819322] __arm64_sys_write+0x70/0xa0 [ 2257.819325] el0_svc_common+0xfc/0x278 [ 2257.819327] el0_svc_handler+0x50/0xc0 [ 2257.819329] el0_svc+0x8/0x1b0 [ 2257.819329] [ 2257.819330] Freed by task 95166: [ 2257.819332] __kasan_slab_free+0x114/0x200 [ 2257.819334] kasan_slab_free+0x10/0x18 [ 2257.819335] kfree+0x80/0x1f0 [ 2257.819337] iommu_group_remove_device+0x27c/0x560 [ 2257.819338] arm_smmu_remove_device+0xe8/0x190 [ 2257.819339] iommu_bus_notifier+0x134/0x248 [ 2257.819342] notifier_call_chain+0xb0/0x140 [ 2257.819343] blocking_notifier_call_chain+0x6c/0xd8 [ 2257.819344] device_del+0x578/0x940 [ 2257.819346] pci_remove_bus_device+0x114/0x290 [ 2257.819347] pci_stop_and_remove_bus_device_locked+0x2c/0x40 [ 2257.819349] remove_store+0xdc/0xe8 [ 2257.819352] dev_attr_store+0x60/0x80 [ 2257.819353] sysfs_kf_write+0x104/0x170 [ 2257.819354] kernfs_fop_write+0x23c/0x430 [ 2257.819355] __vfs_write+0x7c/0xe8 [ 2257.819357] vfs_write+0x12c/0x3d0 [ 2257.819358] ksys_write+0xd4/0x1d8 [ 2257.819359] __arm64_sys_write+0x70/0xa0 [ 2257.819361] el0_svc_common+0xfc/0x278 [ 2257.819362] el0_svc_handler+0x50/0xc0 [ 2257.819364] el0_svc+0x8/0x1b0 [ 2257.819364] T0 T1 --------------------------------- --------------------------------- |- arm_smmu_evtq_thread |- arm_smmu_remove_device |- arm_smmu_handle_evt |- iommu_group_remove_device |- kfree(dev->iommu_param) |- arm_smmu_find_master |- iommu_report_device_fault |- arm_smmu_remove_master |- mutex_lock( \ &dev->iommu_param->lock) // UAF Reference upstream mainline commit 395ad89d11fd93f79a6b942e91fc409807a63c4b, move arm_smmu_remove_master() before iommu_group_remove_device(), and hold mutex to protect finding master and subsequent handling. Fixes: b525f0a6f9b0 ("iommu/arm-smmu-v3: Add stall support for platform devices") Signed-off-by: Ding Hui <dinghui(a)sangfor.com.cn> --- drivers/iommu/arm-smmu-v3.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c index 3309ae6ebc0b..05cb92da6836 100644 --- a/drivers/iommu/arm-smmu-v3.c +++ b/drivers/iommu/arm-smmu-v3.c @@ -1742,7 +1742,8 @@ arm_smmu_find_master(struct arm_smmu_device *smmu, u32 sid) struct arm_smmu_stream *stream; struct arm_smmu_master_data *master = NULL; - mutex_lock(&smmu->streams_mutex); + lockdep_assert_held(&smmu->streams_mutex); + node = smmu->streams.rb_node; while (node) { stream = rb_entry(node, struct arm_smmu_stream, node); @@ -1755,7 +1756,6 @@ arm_smmu_find_master(struct arm_smmu_device *smmu, u32 sid) break; } } - mutex_unlock(&smmu->streams_mutex); return master; } @@ -1791,9 +1791,12 @@ static int arm_smmu_handle_evt(struct arm_smmu_device *smmu, u64 *evt) if (evt[1] & EVTQ_1_S2) return -EFAULT; + mutex_lock(&smmu->streams_mutex); master = arm_smmu_find_master(smmu, sid); - if (!master) - return -EINVAL; + if (!master) { + ret = -EINVAL; + goto out_unlock; + } /* * The domain is valid until the fault returns, because detach() flushes @@ -1833,6 +1836,8 @@ static int arm_smmu_handle_evt(struct arm_smmu_device *smmu, u64 *evt) arm_smmu_page_response(master->dev, &resp); } +out_unlock: + mutex_unlock(&smmu->streams_mutex); return ret; } @@ -2935,8 +2940,8 @@ static void arm_smmu_remove_device(struct device *dev) iopf_queue_remove_device(dev); if (master->ste.assigned) arm_smmu_detach_dev(dev); - iommu_group_remove_device(dev); arm_smmu_remove_master(smmu, master); + iommu_group_remove_device(dev); iommu_device_unlink(&smmu->iommu, dev); kfree(master); iommu_fwspec_free(dev); -- 2.17.1

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ODD2023-Kernel SIG 开放工作会议
by openEuler conference 19 Apr '23

19 Apr '23

您好！ Kernel SIG 邀请您参加 2023-04-21 16:00 召开的Zoom会议(自动录制) 会议主题：ODD2023-Kernel SIG 开放工作会议会议内容： 1. 华中大网安学院内核贡献团队组建经验分享 2. 互联网领域的挑战与技术 3. ext4文件系统问题（一致性、稳定性）的挖掘和定位 4. 可编程内核技术落地场景分享和未来畅想欢迎继续申报议题~ 会议链接：https://us06web.zoom.us/j/88277699752?pwd=VTB3ZjhFR1pKd0syc3NpMDVDcVRvZz09 会议纪要：https://etherpad.openeuler.org/p/ODD2023_Kernel_SIG 温馨提醒：建议接入会议后修改参会人的姓名，也可以使用您在gitee.com的ID 更多资讯尽在：https://openeuler.org/zh/ Hello! openEuler Kernel SIG invites you to attend the Zoom conference(auto recording) will be held at 2023-04-21 16:00, The subject of the conference is ODD2023-Kernel SIG 开放工作会议, Summary: 1. 华中大网安学院内核贡献团队组建经验分享 2. 互联网领域的挑战与技术 3. ext4文件系统问题（一致性、稳定性）的挖掘和定位 4. 可编程内核技术落地场景分享和未来畅想欢迎继续申报议题~ You can join the meeting at https://us06web.zoom.us/j/88277699752?pwd=VTB3ZjhFR1pKd0syc3NpMDVDcVRvZz09. Add topics at https://etherpad.openeuler.org/p/ODD2023_Kernel_SIG. Note: You are advised to change the participant name after joining the conference or use your ID at gitee.com. More information: https://openeuler.org/en/

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一文解锁 → openEuler Developer Day 2023 游玩指南
by openEuler 19 Apr '23

19 Apr '23

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[PATCH openEuler-1.0-LTS 1/2] x86/speculation: Allow enabling STIBP with legacy IBRS
by Yongqiang Liu 19 Apr '23

19 Apr '23

From: KP Singh <kpsingh(a)kernel.org> stable inclusion from stable-v4.19.276 commit 10543fb3c9b019e45e2045f08f46fdf526add593 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I6V7TU CVE: CVE-2023-1998 -------------------------------- commit 6921ed9049bc7457f66c1596c5b78aec0dae4a9d upstream. When plain IBRS is enabled (not enhanced IBRS), the logic in spectre_v2_user_select_mitigation() determines that STIBP is not needed. The IBRS bit implicitly protects against cross-thread branch target injection. However, with legacy IBRS, the IBRS bit is cleared on returning to userspace for performance reasons which leaves userspace threads vulnerable to cross-thread branch target injection against which STIBP protects. Exclude IBRS from the spectre_v2_in_ibrs_mode() check to allow for enabling STIBP (through seccomp/prctl() by default or always-on, if selected by spectre_v2_user kernel cmdline parameter). [ bp: Massage. ] Fixes: 7c693f54c873 ("x86/speculation: Add spectre_v2=ibrs option to support Kernel IBRS") Reported-by: José Oliveira <joseloliveira11(a)gmail.com> Reported-by: Rodrigo Branco <rodrigo(a)kernelhacking.com> Signed-off-by: KP Singh <kpsingh(a)kernel.org> Signed-off-by: Borislav Petkov (AMD) <bp(a)alien8.de> Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/r/20230220120127.1975241-1-kpsingh@kernel.org Link: https://lore.kernel.org/r/20230221184908.2349578-1-kpsingh@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Signed-off-by: Wei Li <liwei391(a)huawei.com> Reviewed-by: Wang Weiyang <wangweiyang2(a)huawei.com> Reviewed-by: Xiongfeng Wang <wangxiongfeng2(a)huawei.com> Signed-off-by: Yongqiang Liu <liuyongqiang13(a)huawei.com> --- arch/x86/kernel/cpu/bugs.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 836000481438..a7becbe9a890 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -973,14 +973,18 @@ spectre_v2_parse_user_cmdline(void) return SPECTRE_V2_USER_CMD_AUTO; } -static inline bool spectre_v2_in_ibrs_mode(enum spectre_v2_mitigation mode) +static inline bool spectre_v2_in_eibrs_mode(enum spectre_v2_mitigation mode) { - return mode == SPECTRE_V2_IBRS || - mode == SPECTRE_V2_EIBRS || + return mode == SPECTRE_V2_EIBRS || mode == SPECTRE_V2_EIBRS_RETPOLINE || mode == SPECTRE_V2_EIBRS_LFENCE; } +static inline bool spectre_v2_in_ibrs_mode(enum spectre_v2_mitigation mode) +{ + return spectre_v2_in_eibrs_mode(mode) || mode == SPECTRE_V2_IBRS; +} + static void __init spectre_v2_user_select_mitigation(void) { @@ -1043,12 +1047,19 @@ spectre_v2_user_select_mitigation(void) } /* - * If no STIBP, IBRS or enhanced IBRS is enabled, or SMT impossible, - * STIBP is not required. + * If no STIBP, enhanced IBRS is enabled, or SMT impossible, STIBP + * is not required. + * + * Enhanced IBRS also protects against cross-thread branch target + * injection in user-mode as the IBRS bit remains always set which + * implicitly enables cross-thread protections. However, in legacy IBRS + * mode, the IBRS bit is set only on kernel entry and cleared on return + * to userspace. This disables the implicit cross-thread protection, + * so allow for STIBP to be selected in that case. */ if (!boot_cpu_has(X86_FEATURE_STIBP) || !smt_possible || - spectre_v2_in_ibrs_mode(spectre_v2_enabled)) + spectre_v2_in_eibrs_mode(spectre_v2_enabled)) return; /* @@ -2084,7 +2095,7 @@ static ssize_t mmio_stale_data_show_state(char *buf) static char *stibp_state(void) { - if (spectre_v2_in_ibrs_mode(spectre_v2_enabled)) + if (spectre_v2_in_eibrs_mode(spectre_v2_enabled)) return ""; switch (spectre_v2_user_stibp) { -- 2.25.1

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[PATCH openEuler-22.03-LTS 00/26] Backport CVEs and bugfixes
by Jialin Zhang 18 Apr '23

18 Apr '23

Pull new CVEs: CVE-2023-1829 CVE-2022-36280 CVE-2022-1015 CVE-2023-1989 CVE-2023-30456 CVE-2023-1990 xfs bugfixes from Long Li and yangerkun

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[PATCH openEuler-22.03-LTS-SP1 00/26] Backport CVEs and bugfixes
by Jialin Zhang 18 Apr '23

18 Apr '23

Pull new CVEs: CVE-2023-1829 CVE-2022-36280 CVE-2022-1015 CVE-2023-1989 CVE-2023-30456 CVE-2023-1990 xfs bugfixes from Long Li and yangerkun

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[PATCH OLK-5.10 00/26] Backport CVEs and bugfixes
by Jialin Zhang 18 Apr '23

18 Apr '23

Pull new CVEs: CVE-2023-1829 CVE-2022-36280 CVE-2022-1015 CVE-2023-1989 CVE-2023-30456 CVE-2023-1990 xfs bugfixes from Long Li and yangerkun

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[PATCH OLK-5.10 000/370] Backport 5.10.150 LTS
by Jialin Zhang 18 Apr '23

18 Apr '23

Backport 5.10.150 LTS patches from upstream. Conflicts: Already merged(19): f039b43cbaea inet: fully convert sk->sk_rx_dst to RCU rules 45c33966759e mm: hugetlb: fix UAF in hugetlb_handle_userfault c378c479c517 io_uring/af_unix: defer registered files gc to io_uring release 67cbc8865a66 io_uring: correct pinned_vm accounting 904f881b5736 arm64: topology: fix possible overflow in amu_fie_setup() dbcca76435a6 HID: roccat: Fix use-after-free in roccat_read() 484400d433ca r8152: Rate limit overflow messages d88b88514ef2 crypto: hisilicon/zip - fix mismatch in get/set sgl_sge_nr 657de36c72f5 arm64: ftrace: fix module PLTs with mcount 29f50bcf0f8b net: mvpp2: fix mvpp2 debugfs leak 6cc0e2afc6a1 bnx2x: fix potential memory leak in bnx2x_tpa_stop() 2a1d03632085 mISDN: fix use-after-free bugs in l1oip timer handlers 0cf6c09dafee ring-buffer: Fix race between reset page and reading page fbb0e601bd51 ext4: ext4_read_bh_lock() should submit IO if the buffer isn't uptodate 483831ad0440 ext4: fix check for block being out of directory size f34ab9516276 ext4: fix null-ptr-deref in ext4_write_info e50472949604 fbdev: smscufx: Fix use-after-free in ufx_ops_open() 7d551b7d6114 block: fix inflight statistics of part0 6b7ae4a904a4 quota: Check next/prev free block number after reading from quota file Context conflict(1): c13d0d2f5a48 usb: host: xhci-plat: suspend and resume clocks Total patches: 389 - 19 = 370

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[PATCH OLK-5.10] x86/speculation: Allow enabling STIBP with legacy IBRS
by Wei Li 18 Apr '23

18 Apr '23

From: KP Singh <kpsingh(a)kernel.org> stable inclusion from stable-v5.10.173 commit abfed855f05863d292de2d0ebab4656791bab9c8 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I6V7TU CVE: CVE-2023-1998 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id… -------------------------------- commit 6921ed9049bc7457f66c1596c5b78aec0dae4a9d upstream. When plain IBRS is enabled (not enhanced IBRS), the logic in spectre_v2_user_select_mitigation() determines that STIBP is not needed. The IBRS bit implicitly protects against cross-thread branch target injection. However, with legacy IBRS, the IBRS bit is cleared on returning to userspace for performance reasons which leaves userspace threads vulnerable to cross-thread branch target injection against which STIBP protects. Exclude IBRS from the spectre_v2_in_ibrs_mode() check to allow for enabling STIBP (through seccomp/prctl() by default or always-on, if selected by spectre_v2_user kernel cmdline parameter). [ bp: Massage. ] Fixes: 7c693f54c873 ("x86/speculation: Add spectre_v2=ibrs option to support Kernel IBRS") Reported-by: José Oliveira <joseloliveira11(a)gmail.com> Reported-by: Rodrigo Branco <rodrigo(a)kernelhacking.com> Signed-off-by: KP Singh <kpsingh(a)kernel.org> Signed-off-by: Borislav Petkov (AMD) <bp(a)alien8.de> Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/r/20230220120127.1975241-1-kpsingh@kernel.org Link: https://lore.kernel.org/r/20230221184908.2349578-1-kpsingh@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Signed-off-by: Wei Li <liwei391(a)huawei.com> --- arch/x86/kernel/cpu/bugs.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 25f3fad210e0..0dd4f8a8d821 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1051,14 +1051,18 @@ spectre_v2_parse_user_cmdline(void) return SPECTRE_V2_USER_CMD_AUTO; } -static inline bool spectre_v2_in_ibrs_mode(enum spectre_v2_mitigation mode) +static inline bool spectre_v2_in_eibrs_mode(enum spectre_v2_mitigation mode) { - return mode == SPECTRE_V2_IBRS || - mode == SPECTRE_V2_EIBRS || + return mode == SPECTRE_V2_EIBRS || mode == SPECTRE_V2_EIBRS_RETPOLINE || mode == SPECTRE_V2_EIBRS_LFENCE; } +static inline bool spectre_v2_in_ibrs_mode(enum spectre_v2_mitigation mode) +{ + return spectre_v2_in_eibrs_mode(mode) || mode == SPECTRE_V2_IBRS; +} + static void __init spectre_v2_user_select_mitigation(void) { @@ -1121,12 +1125,19 @@ spectre_v2_user_select_mitigation(void) } /* - * If no STIBP, IBRS or enhanced IBRS is enabled, or SMT impossible, - * STIBP is not required. + * If no STIBP, enhanced IBRS is enabled, or SMT impossible, STIBP + * is not required. + * + * Enhanced IBRS also protects against cross-thread branch target + * injection in user-mode as the IBRS bit remains always set which + * implicitly enables cross-thread protections. However, in legacy IBRS + * mode, the IBRS bit is set only on kernel entry and cleared on return + * to userspace. This disables the implicit cross-thread protection, + * so allow for STIBP to be selected in that case. */ if (!boot_cpu_has(X86_FEATURE_STIBP) || !smt_possible || - spectre_v2_in_ibrs_mode(spectre_v2_enabled)) + spectre_v2_in_eibrs_mode(spectre_v2_enabled)) return; /* @@ -2220,7 +2231,7 @@ static ssize_t mmio_stale_data_show_state(char *buf) static char *stibp_state(void) { - if (spectre_v2_in_ibrs_mode(spectre_v2_enabled)) + if (spectre_v2_in_eibrs_mode(spectre_v2_enabled)) return ""; switch (spectre_v2_user_stibp) { -- 2.25.1

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Kernel April 2023