On Tue, May 09, 2023 at 12:56:54PM -0400, Kent Overstreet wrote: > From: Kent Overstreet <kent.overstreet@xxxxxxxxx> > > printbuf now needs to know the number of characters that would have been > written if the buffer was too small, like snprintf(); this changes > string_get_size() to return the the return value of snprintf(). Unfortunately, snprintf doesn't return characters written, it return what it TRIED to write, and can cause a lot of problems[1]. This patch would be fine with me if the snprintf was also replaced by scnprintf, which will return the actual string length copied (or 0) *not* including the trailing %NUL. > [...] > @@ -126,8 +126,8 @@ void string_get_size(u64 size, u64 blk_size, const enum string_size_units units, > else > unit = units_str[units][i]; > > - snprintf(buf, len, "%u%s %s", (u32)size, > - tmp, unit); > + return snprintf(buf, len, "%u%s %s", (u32)size, > + tmp, unit); -Kees [1] https://github.com/KSPP/linux/issues/105 -- Kees Cook
