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kmsan_report.c
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kmsan_report.c
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/*
* KMSAN error reporting routines.
*
* Copyright (C) 2019 Google LLC
* Author: Alexander Potapenko <glider@google.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
*/
#include <linux/console.h>
#include <linux/stackdepot.h>
#include <linux/stacktrace.h>
#include "kmsan.h"
DEFINE_SPINLOCK(report_lock);
void kmsan_print_origin(depot_stack_handle_t origin)
{
unsigned long *entries = NULL, *chained_entries = NULL;
unsigned long nr_entries, chained_nr_entries, magic;
char *descr = NULL;
void *pc1 = NULL, *pc2 = NULL;
depot_stack_handle_t head;
if (!origin) {
kmsan_pr_err("Origin not found, presumably a false report.\n");
return;
}
while (true) {
nr_entries = stack_depot_fetch(origin, &entries);
magic = nr_entries ? (entries[0] & KMSAN_MAGIC_MASK) : 0;
if ((nr_entries == 4) && (magic == KMSAN_ALLOCA_MAGIC_ORIGIN)) {
descr = (char *)entries[1];
pc1 = (void *)entries[2];
pc2 = (void *)entries[3];
kmsan_pr_err("Local variable description: %s\n", descr);
kmsan_pr_err("Variable was created at:\n");
kmsan_pr_err(" %pS\n", pc1);
kmsan_pr_err(" %pS\n", pc2);
break;
}
if ((nr_entries == 3) &&
(magic == KMSAN_CHAIN_MAGIC_ORIGIN_FULL)) {
head = entries[1];
origin = entries[2];
kmsan_pr_err("Uninit was stored to memory at:\n");
chained_nr_entries =
stack_depot_fetch(head, &chained_entries);
stack_trace_print(chained_entries, chained_nr_entries,
0);
kmsan_pr_err("\n");
continue;
}
kmsan_pr_err("Uninit was created at:\n");
if (entries)
stack_trace_print(entries, nr_entries, 0);
else
kmsan_pr_err("No stack\n");
break;
}
}
void kmsan_report(depot_stack_handle_t origin,
void *address, int size, int off_first, int off_last,
const void *user_addr, int reason)
{
unsigned long flags;
unsigned long *entries;
unsigned int nr_entries;
if (!kmsan_ready)
return;
if (!current->kmsan.allow_reporting)
return;
if (is_console_locked() || is_logbuf_locked())
return;
/* TODO(glider): temporarily disabling reports without origins. */
if (!origin)
return;
nr_entries = stack_depot_fetch(origin, &entries);
/* TODO(glider) */
current->kmsan.allow_reporting = false;
current->kmsan.is_reporting = true;
spin_lock_irqsave(&report_lock, flags);
kmsan_pr_err("=====================================================\n");
if (get_dsh_extra_bits(origin) == 1)
reason = REASON_USE_AFTER_FREE;
switch (reason) {
case REASON_ANY:
kmsan_pr_err("BUG: KMSAN: uninit-value in %pS\n",
kmsan_internal_return_address(2));
break;
case REASON_COPY_TO_USER:
kmsan_pr_err("BUG: KMSAN: kernel-infoleak in %pS\n",
kmsan_internal_return_address(2));
break;
case REASON_USE_AFTER_FREE:
kmsan_pr_err("BUG: KMSAN: use-after-free in %pS\n",
kmsan_internal_return_address(2));
break;
case REASON_SUBMIT_URB:
kmsan_pr_err("BUG: KMSAN: kernel-usb-infoleak in %pS\n",
kmsan_internal_return_address(2));
break;
}
dump_stack();
kmsan_pr_err("\n");
kmsan_print_origin(origin);
if (size) {
kmsan_pr_err("\n");
if (off_first == off_last)
kmsan_pr_err("Byte %d of %d is uninitialized\n",
off_first, size);
else
kmsan_pr_err("Bytes %d-%d of %d are uninitialized\n",
off_first, off_last, size);
}
if (address)
kmsan_pr_err("Memory access of size %d starts at %px\n",
size, address);
if (user_addr && reason == REASON_COPY_TO_USER)
kmsan_pr_err("Data copied to user address %px\n", user_addr);
kmsan_pr_err("=====================================================\n");
add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
spin_unlock_irqrestore(&report_lock, flags);
if (panic_on_warn)
panic("panic_on_warn set ...\n");
current->kmsan.is_reporting = false;
current->kmsan.allow_reporting = true;
}