On Tuesday 07 March 2006 22:29, Chuck Ebbert wrote:
> In-Reply-To: <[email protected]>
>
> On Tue, 7 Mar 2006 16:54:55 -0800, Greg KH wrote:
>
> > On Tue, Mar 07, 2006 at 04:54:24PM -0500, Chuck Ebbert wrote:
> > > At least one susbsystem rolls its own method of adding env vars to the
> > > uevent buffer, and it's so broken it triggers the WARN_ON() in
> > > lib/vsprintf.c::vsnprintf() by passing a negative length to that function.
> > > Start at drivers/input/input.c::input_dev_uevent() and watch the fun.
> >
> > All of the INPUT_ADD_HOTPLUG_VAR() calls do use add_uevent_var(), so we
> > should be safe there. The other calls also look safe, if not a bit
> > wierd... So I don't see how we could change this to be any safer, do
> > you?
>
> input.c line 747+ was recently added and caused the error message:
>
> [1]=> envp[i++] = buffer + len;
> [2]=> len += snprintf(buffer + len, buffer_size - len, "MODALIAS=");
> [2]=> len += print_modalias(buffer + len, buffer_size - len, dev) + 1;
>
> [1]=> envp[i] = NULL;
> return 0;
>
> [1] What is checking for enough space here? This didn't overflow AFAICT
> but it could.
>
> [2] The snprintf() and print_modalias() calls don't check for errors and
> thus don't return -ENOMEM when the buffer does fill up. Shouldn't they
> do that instead of returning a truncated env string? Only the final
> sanity test in snprintf() keeps them from overrunning the buffer.
> (It was print_modalias_bits() that actually caused the overflow.)
>
I agree with all of the above, it will be fixed.
--
Dmitry
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