tree 719a3ab8be442c786a9d5b02276ad8aaf989075a
parent 99aea68134f3c2a27b4d463c91cfa298c3efaccf
author Al Viro <viro@zeniv.linux.org.uk> 1395548920 -0400
committer Al Viro <viro@zeniv.linux.org.uk> 1395548920 -0400

make prepend_name() work correctly when called with negative *buflen

In all callchains leading to prepend_name(), the value left in *buflen
is eventually discarded unused if prepend_name() has returned a negative.
So we are free to do what prepend() does, and subtract from *buflen
*before* checking for underflow (which turns into checking the sign
of subtraction result, of course).

Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>