From: Sergey Kaplun via Tarantool-patches <tarantool-patches@dev.tarantool.org> To: Maxim Kokryashkin <m.kokryashkin@tarantool.org>, Sergey Bronnikov <sergeyb@tarantool.org> Cc: tarantool-patches@dev.tarantool.org Subject: [Tarantool-patches] [PATCH luajit] Limit exponent range in number parsing. Date: Tue, 21 Nov 2023 11:52:53 +0300 [thread overview] Message-ID: <20231121085253.13526-1-skaplun@tarantool.org> (raw) From: Mike Pall <mike> Reported by XmiliaH. (cherry-picked from commit e56048753634c32ea6eeedf74cef6f9cfea5f4ed) When parsing exponent powers greater than (1 << 16) * 10 == (65536 * 10), the exponent values are cut without handling any values greater. This patch fixes the behaviour, but restricts the power maximum value by `STRSCAN_MAXEXP` (1 << 20). Sergey Kaplun: * added the description and the test for the problem Part of tarantool/tarantool#9145 --- Branch: https://github.com/tarantool/luajit/tree/skaplun/lj-788-limit-exponents-range Tarantool PR: https://github.com/tarantool/tarantool/pull/9386 Related issues: * https://github.com/LuaJIT/LuaJIT/issues/788 * https://github.com/tarantool/tarantool/issues/9145 src/lj_strscan.c | 5 +++- .../lj-788-limit-exponents-range.test.lua | 29 +++++++++++++++++++ 2 files changed, 33 insertions(+), 1 deletion(-) create mode 100644 test/tarantool-tests/lj-788-limit-exponents-range.test.lua diff --git a/src/lj_strscan.c b/src/lj_strscan.c index ae8945e1..129010fd 100644 --- a/src/lj_strscan.c +++ b/src/lj_strscan.c @@ -63,6 +63,7 @@ #define STRSCAN_MAXDIG 800 /* 772 + extra are sufficient. */ #define STRSCAN_DDIG (STRSCAN_DIG/2) #define STRSCAN_DMASK (STRSCAN_DDIG-1) +#define STRSCAN_MAXEXP (1 << 20) /* Helpers for circular buffer. */ #define DNEXT(a) (((a)+1) & STRSCAN_DMASK) @@ -449,6 +450,7 @@ StrScanFmt lj_strscan_scan(const uint8_t *p, MSize len, TValue *o, if (dig) { ex = (int32_t)(dp-(p-1)); dp = p-1; while (ex < 0 && *dp-- == '0') ex++, dig--; /* Skip trailing zeros. */ + if (ex <= -STRSCAN_MAXEXP) return STRSCAN_ERROR; if (base == 16) ex *= 4; } } @@ -462,7 +464,8 @@ StrScanFmt lj_strscan_scan(const uint8_t *p, MSize len, TValue *o, if (!lj_char_isdigit(*p)) return STRSCAN_ERROR; xx = (*p++ & 15); while (lj_char_isdigit(*p)) { - if (xx < 65536) xx = xx * 10 + (*p & 15); + xx = xx * 10 + (*p & 15); + if (xx >= STRSCAN_MAXEXP) return STRSCAN_ERROR; p++; } ex += negx ? -(int32_t)xx : (int32_t)xx; diff --git a/test/tarantool-tests/lj-788-limit-exponents-range.test.lua b/test/tarantool-tests/lj-788-limit-exponents-range.test.lua new file mode 100644 index 00000000..8ab31600 --- /dev/null +++ b/test/tarantool-tests/lj-788-limit-exponents-range.test.lua @@ -0,0 +1,29 @@ +local tap = require('tap') + +-- Test file to demonstrate incorrect behaviour of exponent number +-- form parsing. +-- See also: https://github.com/LuaJIT/LuaJIT/issues/788. +local test = tap.test('lj-788-limit-exponents-range') +test:plan(2) + +-- Before the patch, the powers greater than (1 << 16) * 10 +-- (655360) were parsed incorrectly. After the patch, powers +-- greater than 1 << 20 (1048576 `STRSCAN_MAXEXP`) are considered +-- invalid. See <src/lj_strscan.c> for details. +-- Choose the first value between these values and the second +-- value bigger than `STRSCAN_MAXEXP` to check parsing correctness +-- for the first one, and `STRSCAN_ERROR` for the second case. +local PARSABLE_EXP_POWER = 1000000 +local TOO_LARGE_EXP_POWER = 1050000 + +local function form_exp_string(n) + return '0.' .. string.rep('0', n - 1) .. '1e' .. tostring(n) +end + +test:is(tonumber(form_exp_string(PARSABLE_EXP_POWER)), 1, + 'correct parsing of large exponent') + +test:is(tonumber(form_exp_string(TOO_LARGE_EXP_POWER)), nil, + 'too big exponent power is not parsed') + +test:done(true) -- 2.42.1
next reply other threads:[~2023-11-21 8:57 UTC|newest] Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-11-21 8:52 Sergey Kaplun via Tarantool-patches [this message] 2023-11-21 23:14 ` Maxim Kokryashkin via Tarantool-patches 2024-01-23 21:14 ` Sergey Kaplun via Tarantool-patches 2024-01-25 7:47 ` Sergey Bronnikov via Tarantool-patches 2024-01-25 10:06 ` Sergey Kaplun via Tarantool-patches 2024-01-25 16:31 ` Sergey Bronnikov via Tarantool-patches 2024-02-15 13:50 ` Igor Munkin via Tarantool-patches
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