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Date: Mon, 8 Nov 2021 13:12:37 +0530 From: Ajay Garg <ajaygargnsit@...il.com> To: Andy Shevchenko <andy.shevchenko@...il.com> Cc: "andy@...nel.org" <andy@...nel.org>, Kees Cook <keescook@...omium.org>, "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>, "adobriyan@...il.com" <adobriyan@...il.com>, Nick Desaulniers <ndesaulniers@...gle.com>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, "linux-hardening@...r.kernel.org" <linux-hardening@...r.kernel.org> Subject: Re: RFC for a new string-copy function, using mixtures of strlcpy and strscpy >> >> The output is as follows : >> >> ###################################################### >> Using [strlcpy] :: >> >> len = [16] >> a = [123456789] >> >> >> Using [strscpy] :: >> >> len = [-7] >> a = [123456789] >> > > My gosh, this is error code that you must check. We do not need more string copy functions. > > Hmm, having the additional function would make things a lot easier. For example, in file fs/kernfs/dir.c, there are methods like "kernfs_name_locked", "kernfs_path_from_node_locked" which simply consume the return-value without any checks. All the above functions have a simple motive : copy as much bytes as possible in the destination buffer, and then consume/return the number of bytes actually copied (minus the null-terminator byte of course). If checks are to be put in-place, it would be too much code/churn, adding if checks all over the place. If, instead we do a simple replace of "strlcpy" with "strlscpy" at these places, we would be good to go (while *really* meeting the requirements of these clients at the same time). Anyhow, may be we can wait for some more opinions.
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