[PATCH 3/3] getcwd: Set errno to ERANGE for size == 1 (CVE-2021-3999)

[Siddhesh Poyarekar]

On 18/01/2022 18:43, Andreas Schwab wrote:
> On Jan 18 2022, Siddhesh Poyarekar wrote:
> 
>> We then process it to try and get the cwd anyway by using the posix
>> variant.
> 
> Which returns the appropriate error.
> 

In the specific case of an unprivileged mount on the same directory, it 
ends up underflowing the buffer before returning.  Whether it returns 
the right error or not becomes irrelevant then.  Please see the reproducer.

Siddhesh