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author | 2017-09-06 14:26:02 +0800 | |
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committer | 2017-09-06 08:17:33 -0600 | |
commit | 9276717b9e297a62d1151a43d1cd286213f68eb7 (patch) | |
tree | 4b2a34a8ee2f8f8c01138558b064b655e3d1424a /drivers/md | |
parent | bcache: Update continue_at() documentation (diff) | |
download | linux-9276717b9e297a62d1151a43d1cd286213f68eb7.tar.gz linux-9276717b9e297a62d1151a43d1cd286213f68eb7.tar.bz2 linux-9276717b9e297a62d1151a43d1cd286213f68eb7.zip |
bcache: fix bch_hprint crash and improve output
Most importantly, solve a crash where %llu was used to format signed
numbers. This would cause a buffer overflow when reading sysfs
writeback_rate_debug, as only 20 bytes were allocated for this and
%llu writes 20 characters plus a null.
Always use the units mechanism rather than having different output
paths for simplicity.
Also, correct problems with display output where 1.10 was a larger
number than 1.09, by multiplying by 10 and then dividing by 1024 instead
of dividing by 100. (Remainders of >= 1000 would print as .10).
Minor changes: Always display the decimal point instead of trying to
omit it based on number of digits shown. Decide what units to use
based on 1000 as a threshold, not 1024 (in other words, always print
at most 3 digits before the decimal point).
Signed-off-by: Michael Lyle <mlyle@lyle.org>
Reported-by: Dmitry Yu Okunev <dyokunev@ut.mephi.ru>
Acked-by: Kent Overstreet <kent.overstreet@gmail.com>
Reviewed-by: Coly Li <colyli@suse.de>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/md')
-rw-r--r-- | drivers/md/bcache/util.c | 50 |
1 files changed, 35 insertions, 15 deletions
diff --git a/drivers/md/bcache/util.c b/drivers/md/bcache/util.c index 8c3a938f4bf0..176d3c2ef5f5 100644 --- a/drivers/md/bcache/util.c +++ b/drivers/md/bcache/util.c @@ -74,24 +74,44 @@ STRTO_H(strtouint, unsigned int) STRTO_H(strtoll, long long) STRTO_H(strtoull, unsigned long long) +/** + * bch_hprint() - formats @v to human readable string for sysfs. + * + * @v - signed 64 bit integer + * @buf - the (at least 8 byte) buffer to format the result into. + * + * Returns the number of bytes used by format. + */ ssize_t bch_hprint(char *buf, int64_t v) { static const char units[] = "?kMGTPEZY"; - char dec[4] = ""; - int u, t = 0; - - for (u = 0; v >= 1024 || v <= -1024; u++) { - t = v & ~(~0 << 10); - v >>= 10; - } - - if (!u) - return sprintf(buf, "%llu", v); - - if (v < 100 && v > -100) - snprintf(dec, sizeof(dec), ".%i", t / 100); - - return sprintf(buf, "%lli%s%c", v, dec, units[u]); + int u = 0, t; + + uint64_t q; + + if (v < 0) + q = -v; + else + q = v; + + /* For as long as the number is more than 3 digits, but at least + * once, shift right / divide by 1024. Keep the remainder for + * a digit after the decimal point. + */ + do { + u++; + + t = q & ~(~0 << 10); + q >>= 10; + } while (q >= 1000); + + if (v < 0) + /* '-', up to 3 digits, '.', 1 digit, 1 character, null; + * yields 8 bytes. + */ + return sprintf(buf, "-%llu.%i%c", q, t * 10 / 1024, units[u]); + else + return sprintf(buf, "%llu.%i%c", q, t * 10 / 1024, units[u]); } ssize_t bch_snprint_string_list(char *buf, size_t size, const char * const list[], |