tree 124cae18194eb40a2e365eafa8ba3c593fc0ca65
parent 415e5b3f1d650807758f6953625b78df0207fc6e
author Andrea Arcangeli <andrea@cpushare.com> 1501014165 +0200
committer chrmhoffmann <chrmhoffmann@gmail.com> 1502528128 +0200

fs/exec: fix use after free in execve

"file" can be already freed if bprm->file is NULL after
search_binary_handler() return. binfmt_script will do exactly that for
example. If the VM reuses the file after fput run(), this will result in
a use ater free.

So obtain d_is_su before search_binary_handler() runs.

This should explain this crash:

[25333.009554] Unable to handle kernel NULL pointer dereference at virtual address 00000185
[..]
[25333.009918] [2:             am:21861] PC is at do_execve+0x354/0x474

Change-Id: I2a8a814d1c0aa75625be83cb30432cf13f1a0681