Messages in this thread | | | Date | Thu, 27 Aug 2020 15:20:54 -0700 | From | Kees Cook <> | Subject | Re: [Cocci] [PATCH] usb: atm: don't use snprintf() for sysfs attrs |
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On Fri, Aug 28, 2020 at 12:01:34AM +0300, Denis Efremov wrote: > Just FYI, I've send an addition to the device_attr_show.cocci script[1] to turn > simple cases of snprintf (e.g. "%i") to sprintf. Looks like many developers would > like it more than changing snprintf to scnprintf. As for me, I don't like the idea > of automated altering of the original logic from bounded snprint to unbouded one > with sprintf.
Agreed. This just makes me cringe. If the API design declares that when a show() callback starts, buf has been allocated with PAGE_SIZE bytes, then that's how the logic should proceed, and it should be using scnprintf...
show(...) { size_t remaining = PAGE_SIZE;
... remaining -= scnprintf(buf, remaining, "fmt", var args ...); remaining -= scnprintf(buf, remaining, "fmt", var args ...); remaining -= scnprintf(buf, remaining, "fmt", var args ...);
return PAGE_SIZE - remaining; }
-- Kees Cook
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