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ed95f95c86
Instrumentation of arbitrary memory-copy functions, such as user-copies,
may be called with size of 0, which could lead to false positives.
To avoid this, add a comparison in check_access() for size==0, which
will be optimized out for constant sized instrumentation
(__tsan_{read,write}N), and therefore not affect the common-case
fast-path.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
132 lines
3.5 KiB
C
132 lines
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/printk.h>
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#include <linux/random.h>
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#include <linux/types.h>
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#include "encoding.h"
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#define ITERS_PER_TEST 2000
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/* Test requirements. */
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static bool test_requires(void)
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{
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/* random should be initialized for the below tests */
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return prandom_u32() + prandom_u32() != 0;
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}
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/*
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* Test watchpoint encode and decode: check that encoding some access's info,
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* and then subsequent decode preserves the access's info.
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*/
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static bool test_encode_decode(void)
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{
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int i;
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for (i = 0; i < ITERS_PER_TEST; ++i) {
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size_t size = prandom_u32_max(MAX_ENCODABLE_SIZE) + 1;
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bool is_write = !!prandom_u32_max(2);
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unsigned long addr;
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prandom_bytes(&addr, sizeof(addr));
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if (WARN_ON(!check_encodable(addr, size)))
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return false;
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/* Encode and decode */
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{
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const long encoded_watchpoint =
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encode_watchpoint(addr, size, is_write);
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unsigned long verif_masked_addr;
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size_t verif_size;
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bool verif_is_write;
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/* Check special watchpoints */
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if (WARN_ON(decode_watchpoint(
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INVALID_WATCHPOINT, &verif_masked_addr,
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&verif_size, &verif_is_write)))
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return false;
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if (WARN_ON(decode_watchpoint(
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CONSUMED_WATCHPOINT, &verif_masked_addr,
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&verif_size, &verif_is_write)))
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return false;
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/* Check decoding watchpoint returns same data */
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if (WARN_ON(!decode_watchpoint(
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encoded_watchpoint, &verif_masked_addr,
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&verif_size, &verif_is_write)))
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return false;
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if (WARN_ON(verif_masked_addr !=
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(addr & WATCHPOINT_ADDR_MASK)))
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goto fail;
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if (WARN_ON(verif_size != size))
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goto fail;
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if (WARN_ON(is_write != verif_is_write))
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goto fail;
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continue;
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fail:
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pr_err("%s fail: %s %zu bytes @ %lx -> encoded: %lx -> %s %zu bytes @ %lx\n",
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__func__, is_write ? "write" : "read", size,
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addr, encoded_watchpoint,
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verif_is_write ? "write" : "read", verif_size,
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verif_masked_addr);
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return false;
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}
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}
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return true;
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}
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/* Test access matching function. */
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static bool test_matching_access(void)
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{
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if (WARN_ON(!matching_access(10, 1, 10, 1)))
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return false;
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if (WARN_ON(!matching_access(10, 2, 11, 1)))
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return false;
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if (WARN_ON(!matching_access(10, 1, 9, 2)))
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return false;
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if (WARN_ON(matching_access(10, 1, 11, 1)))
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return false;
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if (WARN_ON(matching_access(9, 1, 10, 1)))
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return false;
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/*
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* An access of size 0 could match another access, as demonstrated here.
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* Rather than add more comparisons to 'matching_access()', which would
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* end up in the fast-path for *all* checks, check_access() simply
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* returns for all accesses of size 0.
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*/
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if (WARN_ON(!matching_access(8, 8, 12, 0)))
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return false;
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return true;
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}
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static int __init kcsan_selftest(void)
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{
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int passed = 0;
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int total = 0;
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#define RUN_TEST(do_test) \
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do { \
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++total; \
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if (do_test()) \
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++passed; \
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else \
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pr_err("KCSAN selftest: " #do_test " failed"); \
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} while (0)
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RUN_TEST(test_requires);
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RUN_TEST(test_encode_decode);
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RUN_TEST(test_matching_access);
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pr_info("KCSAN selftest: %d/%d tests passed\n", passed, total);
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if (passed != total)
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panic("KCSAN selftests failed");
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return 0;
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}
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postcore_initcall(kcsan_selftest);
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