OSCL-LXR linux-6.0.1/​drivers/​misc/​lkdtm/​bugs.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  * This is for all the tests related to logic bugs (e.g. bad dereferences,
  * bad alignment, bad loops, bad locking, bad scheduling, deep stacks, and
  * lockups) along with other things that don't fit well into existing LKDTM
  * test source files.
  */
 #include "lkdtm.h"
 #include <linux/list.h>
 #include <linux/sched.h>
 #include <linux/sched/signal.h>
 #include <linux/sched/task_stack.h>
 #include <linux/uaccess.h>
 #include <linux/slab.h>
 
 #if IS_ENABLED(CONFIG_X86_32) && !IS_ENABLED(CONFIG_UML)
 #include <asm/desc.h>
 #endif
 
 struct lkdtm_list {
     struct list_head node;
 };
 
 /*
  * Make sure our attempts to over run the kernel stack doesn't trigger
  * a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we
  * recurse past the end of THREAD_SIZE by default.
  */
 #if defined(CONFIG_FRAME_WARN) && (CONFIG_FRAME_WARN > 0)
 #define REC_STACK_SIZE (_AC(CONFIG_FRAME_WARN, UL) / 2)
 #else
 #define REC_STACK_SIZE (THREAD_SIZE / 8UL)
 #endif
 #define REC_NUM_DEFAULT ((THREAD_SIZE / REC_STACK_SIZE) * 2)
 
 static int recur_count = REC_NUM_DEFAULT;
 
 static DEFINE_SPINLOCK(lock_me_up);
 
 /*
  * Make sure compiler does not optimize this function or stack frame away:
  * - function marked noinline
  * - stack variables are marked volatile
  * - stack variables are written (memset()) and read (buf[..] passed as arg)
  * - function may have external effects (memzero_explicit())
  * - no tail recursion possible
  */
 static int noinline recursive_loop(int remaining)
 {
     volatile char buf[REC_STACK_SIZE];
     volatile int ret;
 
     memset((void *)buf, remaining & 0xFF, sizeof(buf));
     if (!remaining)
         ret = 0;
     else
         ret = recursive_loop((int)buf[remaining % sizeof(buf)] - 1);
     memzero_explicit((void *)buf, sizeof(buf));
     return ret;
 }
 
 /* If the depth is negative, use the default, otherwise keep parameter. */
 void __init lkdtm_bugs_init(int *recur_param)
 {
     if (*recur_param < 0)
         *recur_param = recur_count;
     else
         recur_count = *recur_param;
 }
 
 static void lkdtm_PANIC(void)
 {
     panic("dumptest");
 }
 
 static void lkdtm_BUG(void)
 {
     BUG();
 }
 
 static int warn_counter;
 
 static void lkdtm_WARNING(void)
 {
     WARN_ON(++warn_counter);
 }
 
 static void lkdtm_WARNING_MESSAGE(void)
 {
     WARN(1, "Warning message trigger count: %d\n", ++warn_counter);
 }
 
 static void lkdtm_EXCEPTION(void)
 {
     *((volatile int *) 0) = 0;
 }
 
 static void lkdtm_LOOP(void)
 {
     for (;;)
         ;
 }
 
 static void lkdtm_EXHAUST_STACK(void)
 {
     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");
 }
 
 static noinline void __lkdtm_CORRUPT_STACK(void *stack)
 {
     memset(stack, '\xff', 64);
 }
 
 /* This should trip the stack canary, not corrupt the return address. */
 static noinline void lkdtm_CORRUPT_STACK(void)
 {
     /* Use default char array length that triggers stack protection. */
     char data[8] __aligned(sizeof(void *));
 
     pr_info("Corrupting stack containing char array ...\n");
     __lkdtm_CORRUPT_STACK((void *)&data);
 }
 
 /* Same as above but will only get a canary with -fstack-protector-strong */
 static noinline void lkdtm_CORRUPT_STACK_STRONG(void)
 {
     union {
         unsigned short shorts[4];
         unsigned long *ptr;
     } data __aligned(sizeof(void *));
 
     pr_info("Corrupting stack containing union ...\n");
     __lkdtm_CORRUPT_STACK((void *)&data);
 }
 
 static pid_t stack_pid;
 static unsigned long stack_addr;
 
 static void lkdtm_REPORT_STACK(void)
 {
     volatile uintptr_t magic;
     pid_t pid = task_pid_nr(current);
 
     if (pid != stack_pid) {
         pr_info("Starting stack offset tracking for pid %d\n", pid);
         stack_pid = pid;
         stack_addr = (uintptr_t)&magic;
     }
 
     pr_info("Stack offset: %d\n", (int)(stack_addr - (uintptr_t)&magic));
 }
 
 static pid_t stack_canary_pid;
 static unsigned long stack_canary;
 static unsigned long stack_canary_offset;
 
 static noinline void __lkdtm_REPORT_STACK_CANARY(void *stack)
 {
     int i = 0;
     pid_t pid = task_pid_nr(current);
     unsigned long *canary = (unsigned long *)stack;
     unsigned long current_offset = 0, init_offset = 0;
 
     /* Do our best to find the canary in a 16 word window ... */
     for (i = 1; i < 16; i++) {
         canary = (unsigned long *)stack + i;
 #ifdef CONFIG_STACKPROTECTOR
         if (*canary == current->stack_canary)
             current_offset = i;
         if (*canary == init_task.stack_canary)
             init_offset = i;
 #endif
     }
 
     if (current_offset == 0) {
         /*
          * If the canary doesn't match what's in the task_struct,
          * we're either using a global canary or the stack frame
          * layout changed.
          */
         if (init_offset != 0) {
             pr_err("FAIL: global stack canary found at offset %ld (canary for pid %d matches init_task's)!\n",
                    init_offset, pid);
         } else {
             pr_warn("FAIL: did not correctly locate stack canary :(\n");
             pr_expected_config(CONFIG_STACKPROTECTOR);
         }
 
         return;
     } else if (init_offset != 0) {
         pr_warn("WARNING: found both current and init_task canaries nearby?!\n");
     }
 
     canary = (unsigned long *)stack + current_offset;
     if (stack_canary_pid == 0) {
         stack_canary = *canary;
         stack_canary_pid = pid;
         stack_canary_offset = current_offset;
         pr_info("Recorded stack canary for pid %d at offset %ld\n",
             stack_canary_pid, stack_canary_offset);
     } else if (pid == stack_canary_pid) {
         pr_warn("ERROR: saw pid %d again -- please use a new pid\n", pid);
     } else {
         if (current_offset != stack_canary_offset) {
             pr_warn("ERROR: canary offset changed from %ld to %ld!?\n",
                 stack_canary_offset, current_offset);
             return;
         }
 
         if (*canary == stack_canary) {
             pr_warn("FAIL: canary identical for pid %d and pid %d at offset %ld!\n",
                 stack_canary_pid, pid, current_offset);
         } else {
             pr_info("ok: stack canaries differ between pid %d and pid %d at offset %ld.\n",
                 stack_canary_pid, pid, current_offset);
             /* Reset the test. */
             stack_canary_pid = 0;
         }
     }
 }
 
 static void lkdtm_REPORT_STACK_CANARY(void)
 {
     /* Use default char array length that triggers stack protection. */
     char data[8] __aligned(sizeof(void *)) = { };
 
     __lkdtm_REPORT_STACK_CANARY((void *)&data);
 }
 
 static void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void)
 {
     static u8 data[5] __attribute__((aligned(4))) = {1, 2, 3, 4, 5};
     u32 *p;
     u32 val = 0x12345678;
 
     p = (u32 *)(data + 1);
     if (*p == 0)
         val = 0x87654321;
     *p = val;
 
     if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
         pr_err("XFAIL: arch has CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS\n");
 }
 
 static void lkdtm_SOFTLOCKUP(void)
 {
     preempt_disable();
     for (;;)
         cpu_relax();
 }
 
 static void lkdtm_HARDLOCKUP(void)
 {
     local_irq_disable();
     for (;;)
         cpu_relax();
 }
 
 static void lkdtm_SPINLOCKUP(void)
 {
     /* Must be called twice to trigger. */
     spin_lock(&lock_me_up);
     /* Let sparse know we intended to exit holding the lock. */
     __release(&lock_me_up);
 }
 
 static void lkdtm_HUNG_TASK(void)
 {
     set_current_state(TASK_UNINTERRUPTIBLE);
     schedule();
 }
 
 volatile unsigned int huge = INT_MAX - 2;
 volatile unsigned int ignored;
 
 static void lkdtm_OVERFLOW_SIGNED(void)
 {
     int value;
 
     value = huge;
     pr_info("Normal signed addition ...\n");
     value += 1;
     ignored = value;
 
     pr_info("Overflowing signed addition ...\n");
     value += 4;
     ignored = value;
 }
 
 
 static void lkdtm_OVERFLOW_UNSIGNED(void)
 {
     unsigned int value;
 
     value = huge;
     pr_info("Normal unsigned addition ...\n");
     value += 1;
     ignored = value;
 
     pr_info("Overflowing unsigned addition ...\n");
     value += 4;
     ignored = value;
 }
 
 /* Intentionally using old-style flex array definition of 1 byte. */
 struct array_bounds_flex_array {
     int one;
     int two;
     char data[1];
 };
 
 struct array_bounds {
     int one;
     int two;
     char data[8];
     int three;
 };
 
 static void lkdtm_ARRAY_BOUNDS(void)
 {
     struct array_bounds_flex_array *not_checked;
     struct array_bounds *checked;
     volatile int i;
 
     not_checked = kmalloc(sizeof(*not_checked) * 2, GFP_KERNEL);
     checked = kmalloc(sizeof(*checked) * 2, GFP_KERNEL);
     if (!not_checked || !checked) {
         kfree(not_checked);
         kfree(checked);
         return;
     }
 
     pr_info("Array access within bounds ...\n");
     /* For both, touch all bytes in the actual member size. */
     for (i = 0; i < sizeof(checked->data); i++)
         checked->data[i] = 'A';
     /*
      * For the uninstrumented flex array member, also touch 1 byte
      * beyond to verify it is correctly uninstrumented.
      */
     for (i = 0; i < sizeof(not_checked->data) + 1; i++)
         not_checked->data[i] = 'A';
 
     pr_info("Array access beyond bounds ...\n");
     for (i = 0; i < sizeof(checked->data) + 1; i++)
         checked->data[i] = 'B';
 
     kfree(not_checked);
     kfree(checked);
     pr_err("FAIL: survived array bounds overflow!\n");
     if (IS_ENABLED(CONFIG_UBSAN_BOUNDS))
         pr_expected_config(CONFIG_UBSAN_TRAP);
     else
         pr_expected_config(CONFIG_UBSAN_BOUNDS);
 }
 
 static void lkdtm_CORRUPT_LIST_ADD(void)
 {
     /*
      * Initially, an empty list via LIST_HEAD:
      *  test_head.next = &test_head
      *  test_head.prev = &test_head
      */
     LIST_HEAD(test_head);
     struct lkdtm_list good, bad;
     void *target[2] = { };
     void *redirection = &target;
 
     pr_info("attempting good list addition\n");
 
     /*
      * Adding to the list performs these actions:
      *  test_head.next->prev = &good.node
      *  good.node.next = test_head.next
      *  good.node.prev = test_head
      *  test_head.next = good.node
      */
     list_add(&good.node, &test_head);
 
     pr_info("attempting corrupted list addition\n");
     /*
      * In simulating this "write what where" primitive, the "what" is
      * the address of &bad.node, and the "where" is the address held
      * by "redirection".
      */
     test_head.next = redirection;
     list_add(&bad.node, &test_head);
 
     if (target[0] == NULL && target[1] == NULL)
         pr_err("Overwrite did not happen, but no BUG?!\n");
     else {
         pr_err("list_add() corruption not detected!\n");
         pr_expected_config(CONFIG_DEBUG_LIST);
     }
 }
 
 static void lkdtm_CORRUPT_LIST_DEL(void)
 {
     LIST_HEAD(test_head);
     struct lkdtm_list item;
     void *target[2] = { };
     void *redirection = &target;
 
     list_add(&item.node, &test_head);
 
     pr_info("attempting good list removal\n");
     list_del(&item.node);
 
     pr_info("attempting corrupted list removal\n");
     list_add(&item.node, &test_head);
 
     /* As with the list_add() test above, this corrupts "next". */
     item.node.next = redirection;
     list_del(&item.node);
 
     if (target[0] == NULL && target[1] == NULL)
         pr_err("Overwrite did not happen, but no BUG?!\n");
     else {
         pr_err("list_del() corruption not detected!\n");
         pr_expected_config(CONFIG_DEBUG_LIST);
     }
 }
 
 /* Test that VMAP_STACK is actually allocating with a leading guard page */
 static void lkdtm_STACK_GUARD_PAGE_LEADING(void)
 {
     const unsigned char *stack = task_stack_page(current);
     const unsigned char *ptr = stack - 1;
     volatile unsigned char byte;
 
     pr_info("attempting bad read from page below current stack\n");
 
     byte = *ptr;
 
     pr_err("FAIL: accessed page before stack! (byte: %x)\n", byte);
 }
 
 /* Test that VMAP_STACK is actually allocating with a trailing guard page */
 static void lkdtm_STACK_GUARD_PAGE_TRAILING(void)
 {
     const unsigned char *stack = task_stack_page(current);
     const unsigned char *ptr = stack + THREAD_SIZE;
     volatile unsigned char byte;
 
     pr_info("attempting bad read from page above current stack\n");
 
     byte = *ptr;
 
     pr_err("FAIL: accessed page after stack! (byte: %x)\n", byte);
 }
 
 static void lkdtm_UNSET_SMEP(void)
 {
 #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;
     unsigned long cr4;
     int i;
 
     cr4 = native_read_cr4();
 
     if ((cr4 & X86_CR4_SMEP) != X86_CR4_SMEP) {
         pr_err("FAIL: SMEP not in use\n");
         return;
     }
     cr4 &= ~(X86_CR4_SMEP);
 
     pr_info("trying to clear SMEP normally\n");
     native_write_cr4(cr4);
     if (cr4 == native_read_cr4()) {
         pr_err("FAIL: pinning SMEP failed!\n");
         cr4 |= X86_CR4_SMEP;
         pr_info("restoring SMEP\n");
         native_write_cr4(cr4);
         return;
     }
     pr_info("ok: SMEP did not get cleared\n");
 
     /*
      * To test the post-write pinning verification we need to call
      * directly into the middle of native_write_cr4() where the
      * cr4 write happens, skipping any pinning. This searches for
      * the cr4 writing instruction.
      */
     insn = (unsigned char *)native_write_cr4;
     for (i = 0; i < MOV_CR4_DEPTH; i++) {
         /* mov %rdi, %cr4 */
         if (insn[i] == 0x0f && insn[i+1] == 0x22 && insn[i+2] == 0xe7)
             break;
         /* mov %rdi,%rax; mov %rax, %cr4 */
         if (insn[i]   == 0x48 && insn[i+1] == 0x89 &&
             insn[i+2] == 0xf8 && insn[i+3] == 0x0f &&
             insn[i+4] == 0x22 && insn[i+5] == 0xe0)
             break;
     }
     if (i >= MOV_CR4_DEPTH) {
         pr_info("ok: cannot locate cr4 writing call gadget\n");
         return;
     }
     direct_write_cr4 = (void *)(insn + i);
 
     pr_info("trying to clear SMEP with call gadget\n");
     direct_write_cr4(cr4);
     if (native_read_cr4() & X86_CR4_SMEP) {
         pr_info("ok: SMEP removal was reverted\n");
     } else {
         pr_err("FAIL: cleared SMEP not detected!\n");
         cr4 |= X86_CR4_SMEP;
         pr_info("restoring SMEP\n");
         native_write_cr4(cr4);
     }
 #else
     pr_err("XFAIL: this test is x86_64-only\n");
 #endif
 }
 
 static void lkdtm_DOUBLE_FAULT(void)
 {
 #if IS_ENABLED(CONFIG_X86_32) && !IS_ENABLED(CONFIG_UML)
     /*
      * 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
 }
 
 #ifdef CONFIG_ARM64
 static noinline void change_pac_parameters(void)
 {
     if (IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL)) {
         /* Reset the keys of current task */
         ptrauth_thread_init_kernel(current);
         ptrauth_thread_switch_kernel(current);
     }
 }
 #endif
 
 static noinline void lkdtm_CORRUPT_PAC(void)
 {
 #ifdef CONFIG_ARM64
 #define CORRUPT_PAC_ITERATE 10
     int i;
 
     if (!IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL))
         pr_err("FAIL: kernel not built with CONFIG_ARM64_PTR_AUTH_KERNEL\n");
 
     if (!system_supports_address_auth()) {
         pr_err("FAIL: CPU lacks pointer authentication feature\n");
         return;
     }
 
     pr_info("changing PAC parameters to force function return failure...\n");
     /*
      * PAC is a hash value computed from input keys, return address and
      * stack pointer. As pac has fewer bits so there is a chance of
      * collision, so iterate few times to reduce the collision probability.
      */
     for (i = 0; i < CORRUPT_PAC_ITERATE; i++)
         change_pac_parameters();
 
     pr_err("FAIL: survived PAC changes! Kernel may be unstable from here\n");
 #else
     pr_err("XFAIL: this test is arm64-only\n");
 #endif
 }
 
 static struct crashtype crashtypes[] = {
     CRASHTYPE(PANIC),
     CRASHTYPE(BUG),
     CRASHTYPE(WARNING),
     CRASHTYPE(WARNING_MESSAGE),
     CRASHTYPE(EXCEPTION),
     CRASHTYPE(LOOP),
     CRASHTYPE(EXHAUST_STACK),
     CRASHTYPE(CORRUPT_STACK),
     CRASHTYPE(CORRUPT_STACK_STRONG),
     CRASHTYPE(REPORT_STACK),
     CRASHTYPE(REPORT_STACK_CANARY),
     CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE),
     CRASHTYPE(SOFTLOCKUP),
     CRASHTYPE(HARDLOCKUP),
     CRASHTYPE(SPINLOCKUP),
     CRASHTYPE(HUNG_TASK),
     CRASHTYPE(OVERFLOW_SIGNED),
     CRASHTYPE(OVERFLOW_UNSIGNED),
     CRASHTYPE(ARRAY_BOUNDS),
     CRASHTYPE(CORRUPT_LIST_ADD),
     CRASHTYPE(CORRUPT_LIST_DEL),
     CRASHTYPE(STACK_GUARD_PAGE_LEADING),
     CRASHTYPE(STACK_GUARD_PAGE_TRAILING),
     CRASHTYPE(UNSET_SMEP),
     CRASHTYPE(DOUBLE_FAULT),
     CRASHTYPE(CORRUPT_PAC),
 };
 
 struct crashtype_category bugs_crashtypes = {
     .crashtypes = crashtypes,
     .len        = ARRAY_SIZE(crashtypes),
 };

This page was automatically generated by the 2.1.0 LXR engine. The LXR team