hulk inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I9GCZS CVE: NA
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For the arm64 kernel, when it processes hardware memory errors for synchronize notifications(do_sea()), if the errors is consumed within the kernel, the current processing is panic. However, it is not optimal.
Take copy_from/to_user for example, If ld* triggers a memory error, even in kernel mode, only the associated process is affected. Killing the user process and isolating the corrupt page is a better choice.
New fixup type EX_TYPE_KACCESS_ERR_ZERO_ME_SAFE is added to identify insn that can recover from memory errors triggered by access to kernel memory.
Signed-off-by: Tong Tiangen tongtiangen@huawei.com --- arch/arm64/Kconfig | 1 + arch/arm64/include/asm/asm-extable.h | 31 +++++++++++++++++++++++----- arch/arm64/include/asm/asm-uaccess.h | 4 ++++ arch/arm64/include/asm/extable.h | 1 + arch/arm64/lib/copy_to_user.S | 10 ++++----- arch/arm64/mm/extable.c | 19 +++++++++++++++++ arch/arm64/mm/fault.c | 27 +++++++++++++++++------- 7 files changed, 75 insertions(+), 18 deletions(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index f657a02693cc..890461d3f5e5 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -20,6 +20,7 @@ config ARM64 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2 select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE select ARCH_HAS_CACHE_LINE_SIZE + select ARCH_HAS_COPY_MC if ACPI_APEI_GHES select ARCH_HAS_CURRENT_STACK_POINTER select ARCH_HAS_DEBUG_VIRTUAL select ARCH_HAS_DEBUG_VM_PGTABLE diff --git a/arch/arm64/include/asm/asm-extable.h b/arch/arm64/include/asm/asm-extable.h index 980d1dd8e1a3..9c0664fe1eb1 100644 --- a/arch/arm64/include/asm/asm-extable.h +++ b/arch/arm64/include/asm/asm-extable.h @@ -5,11 +5,13 @@ #include <linux/bits.h> #include <asm/gpr-num.h>
-#define EX_TYPE_NONE 0 -#define EX_TYPE_BPF 1 -#define EX_TYPE_UACCESS_ERR_ZERO 2 -#define EX_TYPE_KACCESS_ERR_ZERO 3 -#define EX_TYPE_LOAD_UNALIGNED_ZEROPAD 4 +#define EX_TYPE_NONE 0 +#define EX_TYPE_BPF 1 +#define EX_TYPE_UACCESS_ERR_ZERO 2 +#define EX_TYPE_KACCESS_ERR_ZERO 3 +#define EX_TYPE_LOAD_UNALIGNED_ZEROPAD 4 +/* kernel access memory error safe */ +#define EX_TYPE_KACCESS_ERR_ZERO_ME_SAFE 5
/* Data fields for EX_TYPE_UACCESS_ERR_ZERO */ #define EX_DATA_REG_ERR_SHIFT 0 @@ -51,6 +53,17 @@ #define _ASM_EXTABLE_UACCESS(insn, fixup) \ _ASM_EXTABLE_UACCESS_ERR_ZERO(insn, fixup, wzr, wzr)
+#define _ASM_EXTABLE_KACCESS_ERR_ZERO_ME_SAFE(insn, fixup, err, zero) \ + __ASM_EXTABLE_RAW(insn, fixup, \ + EX_TYPE_KACCESS_ERR_ZERO_ME_SAFE, \ + ( \ + EX_DATA_REG(ERR, err) | \ + EX_DATA_REG(ZERO, zero) \ + )) + +#define _ASM_EXTABLE_KACCESS_ME_SAFE(insn, fixup) \ + _ASM_EXTABLE_KACCESS_ERR_ZERO_ME_SAFE(insn, fixup, wzr, wzr) + /* * Create an exception table entry for uaccess `insn`, which will branch to `fixup` * when an unhandled fault is taken. @@ -69,6 +82,14 @@ .endif .endm
+/* + * Create an exception table entry for kaccess me(memory error) safe `insn`, which + * will branch to `fixup` when an unhandled fault is taken. + */ + .macro _asm_extable_kaccess_me_safe, insn, fixup + _ASM_EXTABLE_KACCESS_ME_SAFE(\insn, \fixup) + .endm + #else /* __ASSEMBLY__ */
#include <linux/stringify.h> diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h index 5b6efe8abeeb..7bbebfa5b710 100644 --- a/arch/arm64/include/asm/asm-uaccess.h +++ b/arch/arm64/include/asm/asm-uaccess.h @@ -57,6 +57,10 @@ alternative_else_nop_endif .endm #endif
+#define KERNEL_ME_SAFE(l, x...) \ +9999: x; \ + _asm_extable_kaccess_me_safe 9999b, l + #define USER(l, x...) \ 9999: x; \ _asm_extable_uaccess 9999b, l diff --git a/arch/arm64/include/asm/extable.h b/arch/arm64/include/asm/extable.h index 72b0e71cc3de..bc49443bc502 100644 --- a/arch/arm64/include/asm/extable.h +++ b/arch/arm64/include/asm/extable.h @@ -46,4 +46,5 @@ bool ex_handler_bpf(const struct exception_table_entry *ex, #endif /* !CONFIG_BPF_JIT */
bool fixup_exception(struct pt_regs *regs); +bool fixup_exception_me(struct pt_regs *regs); #endif diff --git a/arch/arm64/lib/copy_to_user.S b/arch/arm64/lib/copy_to_user.S index 802231772608..2ac716c0d6d8 100644 --- a/arch/arm64/lib/copy_to_user.S +++ b/arch/arm64/lib/copy_to_user.S @@ -20,7 +20,7 @@ * x0 - bytes not copied */ .macro ldrb1 reg, ptr, val - ldrb \reg, [\ptr], \val + KERNEL_ME_SAFE(9998f, ldrb \reg, [\ptr], \val) .endm
.macro strb1 reg, ptr, val @@ -28,7 +28,7 @@ .endm
.macro ldrh1 reg, ptr, val - ldrh \reg, [\ptr], \val + KERNEL_ME_SAFE(9998f, ldrh \reg, [\ptr], \val) .endm
.macro strh1 reg, ptr, val @@ -36,7 +36,7 @@ .endm
.macro ldr1 reg, ptr, val - ldr \reg, [\ptr], \val + KERNEL_ME_SAFE(9998f, ldr \reg, [\ptr], \val) .endm
.macro str1 reg, ptr, val @@ -44,7 +44,7 @@ .endm
.macro ldp1 reg1, reg2, ptr, val - ldp \reg1, \reg2, [\ptr], \val + KERNEL_ME_SAFE(9998f, ldp \reg1, \reg2, [\ptr], \val) .endm
.macro stp1 reg1, reg2, ptr, val @@ -64,7 +64,7 @@ SYM_FUNC_START(__arch_copy_to_user) 9997: cmp dst, dstin b.ne 9998f // Before being absolutely sure we couldn't copy anything, try harder - ldrb tmp1w, [srcin] +KERNEL_ME_SAFE(9998f, ldrb tmp1w, [srcin]) USER(9998f, sttrb tmp1w, [dst]) add dst, dst, #1 9998: sub x0, end, dst // bytes not copied diff --git a/arch/arm64/mm/extable.c b/arch/arm64/mm/extable.c index 228d681a8715..8c690ae61944 100644 --- a/arch/arm64/mm/extable.c +++ b/arch/arm64/mm/extable.c @@ -72,7 +72,26 @@ bool fixup_exception(struct pt_regs *regs) return ex_handler_uaccess_err_zero(ex, regs); case EX_TYPE_LOAD_UNALIGNED_ZEROPAD: return ex_handler_load_unaligned_zeropad(ex, regs); + case EX_TYPE_KACCESS_ERR_ZERO_ME_SAFE: + return false; }
BUG(); } + +bool fixup_exception_me(struct pt_regs *regs) +{ + const struct exception_table_entry *ex; + + ex = search_exception_tables(instruction_pointer(regs)); + if (!ex) + return false; + + switch (ex->type) { + case EX_TYPE_UACCESS_ERR_ZERO: + case EX_TYPE_KACCESS_ERR_ZERO_ME_SAFE: + return ex_handler_uaccess_err_zero(ex, regs); + } + + return false; +} diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 9bae7fbad7a7..cbe5600912a9 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -732,21 +732,32 @@ static int do_bad(unsigned long far, unsigned long esr, struct pt_regs *regs) return 1; /* "fault" */ }
+/* + * APEI claimed this as a firmware-first notification. + * Some processing deferred to task_work before ret_to_user(). + */ +static bool do_apei_claim_sea(struct pt_regs *regs) +{ + if (user_mode(regs)) { + if (!apei_claim_sea(regs)) + return true; + } else if (IS_ENABLED(CONFIG_ARCH_HAS_COPY_MC)) { + if (fixup_exception_me(regs) && !apei_claim_sea(regs)) + return true; + } + + return false; +} + static int do_sea(unsigned long far, unsigned long esr, struct pt_regs *regs) { const struct fault_info *inf; unsigned long siaddr;
- inf = esr_to_fault_info(esr); - - if (user_mode(regs) && apei_claim_sea(regs) == 0) { - /* - * APEI claimed this as a firmware-first notification. - * Some processing deferred to task_work before ret_to_user(). - */ + if (do_apei_claim_sea(regs)) return 0; - }
+ inf = esr_to_fault_info(esr); if (esr & ESR_ELx_FnV) { siaddr = 0; } else {