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] Fix zero stripping in %g number formatting. Date: Tue, 30 Jan 2024 18:04:37 +0300 [thread overview] Message-ID: <20240130150437.17133-1-skaplun@tarantool.org> (raw) From: Mike Pall <mike> Reported by pwnhacker0x18. (cherry picked from commit 343ce0edaf3906a62022936175b2f5410024cbfc) In the situation when the precision (`prec`) and amount of digits (`hilen`) for the decimal representation are the same and `ndhi` == 0, the `ndlo` part will become 64 (the size of the `nd` stack buffer), and the overflow occurs. This patch adds the corresponding mask (0x3f == 63) for the `ndlo` incrementation result. Sergey Kaplun: * added the description and the test for the problem Part of tarantool/tarantool#9595 --- Branch: https://github.com/tarantool/luajit/tree/skaplun/lj-1149-g-number-formating Tarantool PR: https://github.com/tarantool/tarantool/pull/9633 The test <app-tap/gh-2717-no-quit-sigint.test.lua> fails on M1 with the timeout (see the example [1]). This fail is patch-unrelated, since I've obscured this failure even for the branch without sources changes (tests only). Related Issues: * https://github.com/LuaJIT/LuaJIT/issues/1149 * https://github.com/tarantool/tarantool/issues/9595 [1]: https://github.com/tarantool/luajit/actions/runs/7712549489/job/21020513973#step:8:5522 Duration of failed tests (seconds): * 60.54 app-tap/gh-2717-no-quit-sigint.test.lua src/lj_strfmt_num.c | 3 ++- .../lj-1149-g-number-formating-bufov.test.lua | 20 +++++++++++++++++++ 2 files changed, 22 insertions(+), 1 deletion(-) create mode 100644 test/tarantool-tests/lj-1149-g-number-formating-bufov.test.lua diff --git a/src/lj_strfmt_num.c b/src/lj_strfmt_num.c index c26204b7..c8d9febf 100644 --- a/src/lj_strfmt_num.c +++ b/src/lj_strfmt_num.c @@ -454,7 +454,8 @@ static char *lj_strfmt_wfnum(SBuf *sb, SFormat sf, lua_Number n, char *p) prec--; if (!i) { if (ndlo == ndhi) { prec = 0; break; } - lj_strfmt_wuint9(tail, nd[++ndlo]); + ndlo = (ndlo + 1) & 0x3f; + lj_strfmt_wuint9(tail, nd[ndlo]); i = 9; } } diff --git a/test/tarantool-tests/lj-1149-g-number-formating-bufov.test.lua b/test/tarantool-tests/lj-1149-g-number-formating-bufov.test.lua new file mode 100644 index 00000000..040fd5de --- /dev/null +++ b/test/tarantool-tests/lj-1149-g-number-formating-bufov.test.lua @@ -0,0 +1,20 @@ +local tap = require('tap') + +-- Test file to demonstrate stack-buffer-overflow in the +-- `lj_strfmt_wfnum()` call. +-- See also: https://github.com/LuaJIT/LuaJIT/issues/1149. + +local test = tap.test('lj-1149-g-number-formating-bufov') +test:plan(1) + +-- XXX: The test shows stack-buffer-overflow only under ASAN. +-- The number value for the test is with the same precision +-- (`prec` = 5) and amount of digits (`hilen` = 5) for the decimal +-- representation. Hence, with `ndhi` == 0, the `ndlo` part will +-- become 64 (the size of the `nd` stack buffer), and the overflow +-- occurs. +-- See details in the <src/lj_strfmt_num.c>:`lj_strfmt_wfnum()`. +test:is(string.format('%7g', 0x1.144399609d407p+401), '5.5733e+120', + 'correct format %7g result') + +test:done(true) -- 2.43.0
next reply other threads:[~2024-01-30 15:08 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-01-30 15:04 Sergey Kaplun via Tarantool-patches [this message] 2024-01-31 9:42 ` Maxim Kokryashkin via Tarantool-patches 2024-01-31 9:46 ` Sergey Kaplun via Tarantool-patches 2024-02-01 10:57 ` Sergey Bronnikov via Tarantool-patches 2024-02-15 13:46 ` Igor Munkin via Tarantool-patches
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