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From: "goldstein.w.n at gmail dot com" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug string/27974] New: Overflow bug in some implementation of of wcsnlen, wmemchr, and wcsncat.
Date: Wed, 09 Jun 2021 22:25:11 +0000 [thread overview]
Message-ID: <bug-27974-131@http.sourceware.org/bugzilla/> (raw)
https://sourceware.org/bugzilla/show_bug.cgi?id=27974
Bug ID: 27974
Summary: Overflow bug in some implementation of of wcsnlen,
wmemchr, and wcsncat.
Product: glibc
Version: 2.34
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: string
Assignee: unassigned at sourceware dot org
Reporter: goldstein.w.n at gmail dot com
Target Milestone: ---
The bug is that some implementations assume that maxlen or n from wcsnlen and
wmemchr/wcsncat times sizeof(wchar_t) will not overflow.
It appears, however that there is no defined limit on maxlen * sizeof(wchar_t)
https://marc.info/?l=glibc-alpha&m=162323134028410&w=2
This bug would found in the following x86_64 implementations of wcsnlen and
wmemchr.
wcsnlen-sse4_1 ->
https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/x86_64/strlen.S;h=d223ea1700a7d0cb0dcf9c8f251f09d5b9eea91e;hb=HEAD#l68
wcsnlen-avx2 ->
https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/x86_64/multiarch/strlen-avx2.S;h=bd2e6ee44a8ae113dfdb0de8bc6fc1b405d7ef28;hb=HEAD#l57
wmemchr-sse2 ->
https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/x86_64/memchr.S;h=beff2708de6a1e40de4141f94ff6fe763f041164;hb=HEAD#l39
wmemchr-avx2 ->
https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/x86_64/multiarch/memchr-avx2.S;h=0d8758e3e7190fbe54243312b7ecc2952e85465a;hb=HEAD#l66
This bug will also be present in wcsncat which uses wcsnlen:
https://sourceware.org/git/?p=glibc.git;a=blob;f=wcsmbs/wcsncat.c;h=27de72af6c7733fe0e27661874b64d57659b5ed9;hb=HEAD#l34
For example with a string of length 1000 the following cases would highlight
the bug:
wmemchr(string_length_1000, 0, (2^62) + 1) // would return NULL rather than s +
1000
wcsnlen(string_length_1000, (2^62) + 1) // would return 1 rather than 1000
wcsncat(s2, string_length_1000, (2^62) + 1) // would only copy 1 wide char
--
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next reply other threads:[~2021-06-09 22:25 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-09 22:25 goldstein.w.n at gmail dot com [this message]
2021-06-09 22:25 ` [Bug string/27974] " goldstein.w.n at gmail dot com
2021-06-23 18:29 ` goldstein.w.n at gmail dot com
2022-01-27 21:11 ` [Bug string/27974] Overflow bug in some implementation " hjl.tools at gmail dot com
2022-01-27 22:40 ` cvs-commit at gcc dot gnu.org
2022-01-27 23:19 ` cvs-commit at gcc dot gnu.org
2022-01-28 0:24 ` cvs-commit at gcc dot gnu.org
2022-01-28 0:40 ` cvs-commit at gcc dot gnu.org
2022-01-28 2:21 ` cvs-commit at gcc dot gnu.org
2022-01-28 2:22 ` cvs-commit at gcc dot gnu.org
2022-01-28 2:23 ` hjl.tools at gmail dot com
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