seq_file: disallow extremely large seq buffer allocations

commit 8cae8cd89f05f6de223d63e6d15e31c8ba9cf53b upstream.

There is no reasonable need for a buffer larger than this, and it avoids
int overflow pitfalls.

Change-Id: I0ac12a4a1c51e476a9305e0c9d5247293b3083d4
Fixes: 058504ed ("fs/seq_file: fallback to vmalloc allocation")
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Reported-by: Qualys Security Advisory <qsa@qualys.com>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Git-commit: 6de9f0bf
Git-repo: https://android.googlesource.com/kernel/msm


Signed-off-by: PavanKumar S.R <quic_pavasr@quicinc.com>