arm64: fix oops in concurrently setting insn_emulation sysctls
stable inclusion from stable-v5.10.137 commit 353b4673d01c512303c45cf2346f630cda73b5c9 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I5U71M?from=project-issue CVE: CVE-2022-20422 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=353b4673d01c512303c45cf2346f630cda73b5c9 --------------------------- [ Upstream commit af483947 ] emulation_proc_handler() changes table->data for proc_dointvec_minmax and can generate the following Oops if called concurrently with itself: | Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010 | Internal error: Oops: 96000006 [#1] SMP | Call trace: | update_insn_emulation_mode+0xc0/0x148 | emulation_proc_handler+0x64/0xb8 | proc_sys_call_handler+0x9c/0xf8 | proc_sys_write+0x18/0x20 | __vfs_write+0x20/0x48 | vfs_write+0xe4/0x1d0 | ksys_write+0x70/0xf8 | __arm64_sys_write+0x20/0x28 | el0_svc_common.constprop.0+0x7c/0x1c0 | el0_svc_handler+0x2c/0xa0 | el0_svc+0x8/0x200 To fix this issue, keep the table->data as &insn->current_mode and use container_of() to retrieve the insn pointer. Another mutex is used to protect against the current_mode update but not for retrieving insn_emulation as table->data is no longer changing. Co-developed-by: Nhewenliang <hewenliang4@huawei.com> Signed-off-by: Nhewenliang <hewenliang4@huawei.com> Signed-off-by: NHaibin Zhang <haibinzhang@tencent.com> Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20220128090324.2727688-1-hewenliang4@huawei.com Link: https://lore.kernel.org/r/9A004C03-250B-46C5-BF39-782D7551B00E@tencent.comSigned-off-by: NWill Deacon <will@kernel.org> Signed-off-by: NSasha Levin <sashal@kernel.org> Signed-off-by: Nruanjinjie <ruanjinjie@huawei.com> Reviewed-by: NZhang Jianhua <chris.zjh@huawei.com> Reviewed-by: NLiao Chang <liaochang1@huawei.com> Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
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