lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-ID: <88e8b096-aa04-2447-cb21-a83b5e57e963@gmail.com> Date: Fri, 2 Sep 2022 08:53:34 +0700 From: Bagas Sanjaya <bagasdotme@...il.com> To: Kees Cook <keescook@...omium.org>, Geert Uytterhoeven <geert@...ux-m68k.org> Cc: Wolfram Sang <wsa+renesas@...g-engineering.com>, Nick Desaulniers <ndesaulniers@...gle.com>, Guenter Roeck <linux@...ck-us.net>, Linus Torvalds <torvalds@...ux-foundation.org>, Jonathan Corbet <corbet@....net>, Len Baker <len.baker@....com>, "Gustavo A. R. Silva" <gustavoars@...nel.org>, Francis Laniel <laniel_francis@...vacyrequired.com>, Paolo Abeni <pabeni@...hat.com>, linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org, linux-hardening@...r.kernel.org Subject: Re: [PATCH v2] string: Introduce strtomem() and strtomem_pad() On 9/2/22 02:09, Kees Cook wrote: > One of the "legitimate" uses of strncpy() is copying a NUL-terminated > string into a fixed-size non-NUL-terminated character array. To avoid > the weaknesses and ambiguity of intent when using strncpy(), provide > replacement functions that explicitly distinguish between trailing > padding and not, and require the destination buffer size be discoverable > by the compiler. >> For example: > > struct obj { > int foo; > char small[4] __nonstring; > char big[8] __nonstring; > int bar; > }; > > struct obj p; > > /* This will truncate to 4 chars with no trailing NUL */ > strncpy(p.small, "hello", sizeof(p.small)); > /* p.small contains 'h', 'e', 'l', 'l' */ > > /* This will NUL pad to 8 chars. */ > strncpy(p.big, "hello", sizeof(p.big)); > /* p.big contains 'h', 'e', 'l', 'l', 'o', '\0', '\0', '\0' */ > > When the "__nonstring" attributes are missing, the intent of the > programmer becomes ambiguous for whether the lack of a trailing NUL > in the p.small copy is a bug. Additionally, it's not clear whether > the trailing padding in the p.big copy is _needed_. Both cases > become unambiguous with: > > strtomem(p.small, "hello"); > strtomem_pad(p.big, "hello", 0); > > See also https://github.com/KSPP/linux/issues/90 > Should'nt strscpy() do the job? -- An old man doll... just what I always wanted! - Clara
Powered by blists - more mailing lists