commoncap: don't alloc the credential unless needed in cap_task_prctl

In function cap_task_prctl(), we would allocate a credential
unconditionally and then check if we support the requested function.
If not we would release this credential with abort_creds() by using
RCU method. But on some archs such as powerpc, the sys_prctl is heavily
used to get/set the floating point exception mode. So the unnecessary
allocating/releasing of credential not only introduce runtime overhead
but also do cause OOM due to the RCU implementation.

This patch removes abort_creds() from cap_task_prctl() by calling
prepare_creds() only when we need to modify it.

Reported-by: Kevin Hao <[email protected]>
Signed-off-by: Tetsuo Handa <[email protected]>
Reviewed-by: Paul Moore <[email protected]>
Acked-by: Serge E. Hallyn <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Signed-off-by: James Morris <[email protected]>

0 files changed, 0 insertions, 0 deletions