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time-util: fix buffer-over-run #23933

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merged 1 commit into from
Jul 8, 2022
Merged

time-util: fix buffer-over-run #23933

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2 changes: 1 addition & 1 deletion src/basic/time-util.c
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Original file line number Diff line number Diff line change
Expand Up @@ -591,7 +591,7 @@ char *format_timespan(char *buf, size_t l, usec_t t, usec_t accuracy) {
t = b;
}

n = MIN((size_t) k, l);
n = MIN((size_t) k, l-1);

l -= n;
p += n;
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5 changes: 5 additions & 0 deletions src/test/test-time-util.c
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Expand Up @@ -238,6 +238,11 @@ TEST(format_timespan) {
test_format_timespan_accuracy(1);
test_format_timespan_accuracy(USEC_PER_MSEC);
test_format_timespan_accuracy(USEC_PER_SEC);

/* See issue #23928. */
_cleanup_free_ char *buf;
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Why not just char buf[5]?

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I do not know why, but valgrind does not detect the buffer-over-run if buf[5] is used.
ASAN may detect the issue even with buf[5]. But this is just a test code, hence I hope that's no problem.

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I do not know why, but valgrind does not detect the buffer-over-run if buf[5] is used.

Because valgrind's memcheck doesn't check stack allocations.

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Ah, thanks.

assert_se(buf = new(char, 5));
assert_se(buf == format_timespan(buf, 5, 100005, 1000));
}

TEST(verify_timezone) {
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