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.)
> Are you still seeing problems now?
Wasn't me, it was Horst Schirmeier <[email protected]>
--
Chuck
"Penguins don't come from next door, they come from the Antarctic!"
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