Date: Fri, 27 Aug 2021 12:59:18 -0400 From: Rich Felker <dalias@...c.org> To: Érico Nogueira <ericonr@...root.org> Cc: musl@...ts.openwall.com, Alyssa Ross <hi@...ssa.is> Subject: Re: [PATCH musl 3/3] mntent: fix parsing lines with optional fields On Fri, Aug 27, 2021 at 12:49:28PM -0400, Rich Felker wrote: > On Fri, Aug 27, 2021 at 12:27:36PM -0300, Érico Nogueira wrote: > > Try avoiding unrelated changes in the commit, since they can introduce > > subtle bugs. In this case, making n size_t instead of int will lead > > to pointer type mismatches in the sscanf call, given that %n expects an > > int*. > > > > I don't know if *scanf guarantees it won't read enough to go past > > For *scanf in general there is no such guarantee; not even size_t is > safe for fscanf. However, here you have sscanf and the number is > bounded by strlen(linebuf). > > > INT_MAX, though, so making a change to size_t and using %ln might make > > sense. Deferring to someone else to answer that. > > The conversion specifier for size_t is %zu not %ln. Since in theory > strlen(linebuf) could be more than INT_MAX, I think this change should > be made, but it should be a separate bugfix. Sorry, that should be '%zn'. '%zu' of course is for reading an integer of type size_t not counting the bytes processed.
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