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Message-ID: <20240523202803.GC10433@brightrain.aerifal.cx> Date: Thu, 23 May 2024 16:28:03 -0400 From: Rich Felker <dalias@...c.org> To: Florian Ziesche <florian.ziesche@...il.com> Cc: musl@...ts.openwall.com Subject: Re: [PATCH] dynlink: fix get_lfs64() with posix_fallocate64 On Fri, May 10, 2024 at 06:01:58PM +0200, Florian Ziesche wrote: > Hi, > > this patch increases the buffer size by one in get_lfs64() so that it > works with posix_fallocate64. > "posix_fallocate64" is 17 characters long, so 16 is one too short. > > Simplified example: > before: https://compiler-explorer.com/z/4qcPhcaWr > after: https://compiler-explorer.com/z/scGvhddKW > > --- > diff --git a/ldso/dynlink.c b/ldso/dynlink.c > index 42687da2..8707ae1c 100644 > --- a/ldso/dynlink.c > +++ b/ldso/dynlink.c > @@ -363,7 +363,7 @@ static struct symdef get_lfs64(const char *name) > "stat\0statfs\0statvfs\0tmpfile\0truncate\0versionsort\0" > "__fxstat\0__fxstatat\0__lxstat\0__xstat\0"; > size_t l; > - char buf[16]; > + char buf[17]; > for (l=0; name[l]; l++) { > if (l >= sizeof buf) goto nomatch; > buf[l] = name[l]; Thanks for catching this. I questioned whether the 17 is sufficient, but indeed the buffer is never nul terminated except when removing the 64, so it should be ok. I think I'll apply your patch as a direct fix, but the whole copying operation is unnecessary and I'll probably remove it. It works just as well to strncmp and pass p instead of buf to find_sym, so that a mutable copy of the name to lookup is never needed. Rich
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