projects / pve-kernel.git / blame
| Commit | Line | Data |
|---|---|---|
| 035dbe67 FG |
1 | From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 |
| 2 | From: Tim Chen <tim.c.chen@linux.intel.com> | |
| 3 | Date: Tue, 19 Sep 2017 15:21:40 -0700 | |
| 4 | Subject: [PATCH] x86/syscall: Clear unused extra registers on syscall entrance | |
| 5 | MIME-Version: 1.0 | |
| 6 | Content-Type: text/plain; charset=UTF-8 | |
| 7 | Content-Transfer-Encoding: 8bit | |
| 8 | ||
| 9 | CVE-2017-5753 | |
| 10 | CVE-2017-5715 | |
| 11 | ||
| 12 | To prevent the unused registers %r12-%r15, %rbp and %rbx from | |
| 13 | being used speculatively, we clear them upon syscall entrance | |
| 14 | for code hygiene. | |
| 15 | ||
| 16 | Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> | |
| 17 | Signed-off-by: Andy Whitcroft <apw@canonical.com> | |
| 18 | Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com> | |
| 19 | (cherry picked from commit 7b5ea16f42b5e4860cf9033897bcdfa3e1209033) | |
| 20 | Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com> | |
| 21 | --- | |
| 22 | arch/x86/entry/calling.h | 9 +++++++++ | |
| 23 | arch/x86/entry/entry_64.S | 12 ++++++++---- | |
| 24 | 2 files changed, 17 insertions(+), 4 deletions(-) | |
| 25 | ||
| 26 | diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h | |
| 27 | index 015e0a84bb99..d537818ad285 100644 | |
| 28 | --- a/arch/x86/entry/calling.h | |
| 29 | +++ b/arch/x86/entry/calling.h | |
| 30 | @@ -155,6 +155,15 @@ For 32-bit we have the following conventions - kernel is built with | |
| 31 | popq %rbx | |
| 32 | .endm | |
| 33 | ||
| 34 | + .macro CLEAR_EXTRA_REGS | |
| 35 | + xorq %r15, %r15 | |
| 36 | + xorq %r14, %r14 | |
| 37 | + xorq %r13, %r13 | |
| 38 | + xorq %r12, %r12 | |
| 39 | + xorq %rbp, %rbp | |
| 40 | + xorq %rbx, %rbx | |
| 41 | + .endm | |
| 42 | + | |
| 43 | .macro POP_C_REGS | |
| 44 | popq %r11 | |
| 45 | popq %r10 | |
| 46 | diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S | |
| 47 | index f6ec4ad5b114..1118a6256c69 100644 | |
| 48 | --- a/arch/x86/entry/entry_64.S | |
| 49 | +++ b/arch/x86/entry/entry_64.S | |
| 50 | @@ -231,10 +231,16 @@ GLOBAL(entry_SYSCALL_64_after_hwframe) | |
| 51 | pushq %r9 /* pt_regs->r9 */ | |
| 52 | pushq %r10 /* pt_regs->r10 */ | |
| 53 | pushq %r11 /* pt_regs->r11 */ | |
| 54 | - sub $(6*8), %rsp /* pt_regs->bp, bx, r12-15 not saved */ | |
| 55 | + sub $(6*8), %rsp /* pt_regs->bp, bx, r12-15 not used */ | |
| 56 | UNWIND_HINT_REGS extra=0 | |
| 57 | ||
| 58 | ENABLE_IBRS | |
| 59 | + /* | |
| 60 | + * Clear the unused extra regs for code hygiene. | |
| 61 | + * Will restore the callee saved extra regs at end of syscall. | |
| 62 | + */ | |
| 63 | + SAVE_EXTRA_REGS | |
| 64 | + CLEAR_EXTRA_REGS | |
| 65 | ||
| 66 | STUFF_RSB | |
| 67 | ||
| 68 | @@ -292,7 +298,7 @@ entry_SYSCALL_64_fastpath: | |
| 69 | movq RIP(%rsp), %rcx | |
| 70 | movq EFLAGS(%rsp), %r11 | |
| 71 | DISABLE_IBRS | |
| 72 | - addq $6*8, %rsp /* skip extra regs -- they were preserved */ | |
| 73 | + POP_EXTRA_REGS | |
| 74 | UNWIND_HINT_EMPTY | |
| 75 | jmp .Lpop_c_regs_except_rcx_r11_and_sysret | |
| 76 | ||
| 77 | @@ -304,14 +310,12 @@ entry_SYSCALL_64_fastpath: | |
| 78 | */ | |
| 79 | TRACE_IRQS_ON | |
| 80 | ENABLE_INTERRUPTS(CLBR_ANY) | |
| 81 | - SAVE_EXTRA_REGS | |
| 82 | movq %rsp, %rdi | |
| 83 | call syscall_return_slowpath /* returns with IRQs disabled */ | |
| 84 | jmp return_from_SYSCALL_64 | |
| 85 | ||
| 86 | entry_SYSCALL64_slow_path: | |
| 87 | /* IRQs are off. */ | |
| 88 | - SAVE_EXTRA_REGS | |
| 89 | movq %rsp, %rdi | |
| 90 | call do_syscall_64 /* returns with IRQs disabled */ | |
| 91 | ||
| 92 | -- | |
| 93 | 2.14.2 | |
| 94 |