From: Maxim Kokryashkin via Tarantool-patches <tarantool-patches@dev.tarantool.org>
To: "Sergey Kaplun" <skaplun@tarantool.org>
Cc: tarantool-patches@dev.tarantool.org
Subject: Re: [Tarantool-patches] [PATCH luajit] Limit exponent range in number parsing.
Date: Wed, 22 Nov 2023 02:14:00 +0300 [thread overview]
Message-ID: <1700608440.723465194@f734.i.mail.ru> (raw)
In-Reply-To: <20231121085253.13526-1-skaplun@tarantool.org>
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Hi, Sergey!
Thanks for the patch!
LGTM
--
Best regards,
Maxim Kokryashkin
>Вторник, 21 ноября 2023, 11:57 +03:00 от Sergey Kaplun <skaplun@tarantool.org>:
>
>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
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next prev parent reply other threads:[~2023-11-21 23:14 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-21 8:52 Sergey Kaplun via Tarantool-patches
2023-11-21 23:14 ` Maxim Kokryashkin via Tarantool-patches [this message]
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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