diff options
Diffstat (limited to 'drivers/misc/lkdtm/bugs.c')
| -rw-r--r-- | drivers/misc/lkdtm/bugs.c | 56 |
1 files changed, 51 insertions, 5 deletions
diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c index 1606658b9b7e..de87693cf557 100644 --- a/drivers/misc/lkdtm/bugs.c +++ b/drivers/misc/lkdtm/bugs.c @@ -12,6 +12,10 @@ #include <linux/sched/task_stack.h> #include <linux/uaccess.h> +#ifdef CONFIG_X86_32 +#include <asm/desc.h> +#endif + struct lkdtm_list { struct list_head node; }; @@ -22,7 +26,7 @@ struct lkdtm_list { * recurse past the end of THREAD_SIZE by default. */ #if defined(CONFIG_FRAME_WARN) && (CONFIG_FRAME_WARN > 0) -#define REC_STACK_SIZE (CONFIG_FRAME_WARN / 2) +#define REC_STACK_SIZE (_AC(CONFIG_FRAME_WARN, UL) / 2) #else #define REC_STACK_SIZE (THREAD_SIZE / 8) #endif @@ -75,7 +79,12 @@ static int warn_counter; void lkdtm_WARNING(void) { - WARN(1, "Warning message trigger count: %d\n", warn_counter++); + WARN_ON(++warn_counter); +} + +void lkdtm_WARNING_MESSAGE(void) +{ + WARN(1, "Warning message trigger count: %d\n", ++warn_counter); } void lkdtm_EXCEPTION(void) @@ -91,7 +100,7 @@ void lkdtm_LOOP(void) void lkdtm_EXHAUST_STACK(void) { - pr_info("Calling function with %d frame size to depth %d ...\n", + pr_info("Calling function with %lu frame size to depth %d ...\n", REC_STACK_SIZE, recur_count); recursive_loop(recur_count); pr_info("FAIL: survived without exhausting stack?!\n"); @@ -269,7 +278,7 @@ void lkdtm_STACK_GUARD_PAGE_TRAILING(void) void lkdtm_UNSET_SMEP(void) { -#ifdef CONFIG_X86_64 +#if IS_ENABLED(CONFIG_X86_64) && !IS_ENABLED(CONFIG_UML) #define MOV_CR4_DEPTH 64 void (*direct_write_cr4)(unsigned long val); unsigned char *insn; @@ -329,6 +338,43 @@ void lkdtm_UNSET_SMEP(void) native_write_cr4(cr4); } #else - pr_err("FAIL: this test is x86_64-only\n"); + pr_err("XFAIL: this test is x86_64-only\n"); +#endif +} + +void lkdtm_DOUBLE_FAULT(void) +{ +#ifdef CONFIG_X86_32 + /* + * Trigger #DF by setting the stack limit to zero. This clobbers + * a GDT TLS slot, which is okay because the current task will die + * anyway due to the double fault. + */ + struct desc_struct d = { + .type = 3, /* expand-up, writable, accessed data */ + .p = 1, /* present */ + .d = 1, /* 32-bit */ + .g = 0, /* limit in bytes */ + .s = 1, /* not system */ + }; + + local_irq_disable(); + write_gdt_entry(get_cpu_gdt_rw(smp_processor_id()), + GDT_ENTRY_TLS_MIN, &d, DESCTYPE_S); + + /* + * Put our zero-limit segment in SS and then trigger a fault. The + * 4-byte access to (%esp) will fault with #SS, and the attempt to + * deliver the fault will recursively cause #SS and result in #DF. + * This whole process happens while NMIs and MCEs are blocked by the + * MOV SS window. This is nice because an NMI with an invalid SS + * would also double-fault, resulting in the NMI or MCE being lost. + */ + asm volatile ("movw %0, %%ss; addl $0, (%%esp)" :: + "r" ((unsigned short)(GDT_ENTRY_TLS_MIN << 3))); + + pr_err("FAIL: tried to double fault but didn't die\n"); +#else + pr_err("XFAIL: this test is ia32-only\n"); #endif } |
