Problem Description:
The setcred(2) system call is only available to privileged
users. However, before the privilege level of the caller is checked,
the user-supplied list of supplementary groups is copied into a
fixed-size kernel stack buffer without first validating its length.
If the supplied list exceeds the capacity of that buffer, a stack
buffer overflow occurs.
Impact:
Because the bounds check on the supplementary groups list occurs
after the kernel stack buffer has already been written, an unprivileged
local user may trigger the overflow without holding any special
privilege. Successful exploitation may allow an attacker to execute
arbitrary code in the context of the kernel, allowing an unprivileged
local user to gain elevated privileges on the affected system.