From c7f42f5bcd6ae56cb5657a20aaf8f4a50565b4d3 Mon Sep 17 00:00:00 2001
From: Mister Oyster <oysterized@gmail.com>
Date: Sat, 23 Sep 2017 18:27:49 +0200
Subject: fs: proc: task_mmu: fix proc_mem_open creds for fs access checks

Should fix :
[ 2201.337557]<0> (0)[672:android.bg]WARNING: at
../../../../../../kernel/meizu/m2note/kernel/ptrace.c:239
__ptrace_may_access+0x164/0x178()
[ 2201.337568]<0> (0)[672:android.bg]denying ptrace access check without
PTRACE_MODE_*CREDS
[ 2201.337583]<0> (0)[672:android.bg]CPU: 0 PID: 672 Comm: android.bg
Tainted: G        W    3.10.107-NOyster #1
[ 2201.337593]<0> (0)[672:android.bg]Call trace:
[ 2201.337609]<0> (0)[672:android.bg][<ffffffc000089558>]
dump_backtrace+0x0/0x148
[ 2201.337625]<0> (0)[672:android.bg][<ffffffc0000896b4>]
show_stack+0x14/0x1c
[ 2201.337642]<0> (0)[672:android.bg][<ffffffc0009e88d4>]
dump_stack+0x20/0x28
[ 2201.337657]<0> (0)[672:android.bg][<ffffffc00009b6cc>]
warn_slowpath_fmt+0xb0/0x134
[ 2201.337673]<0> (0)[672:android.bg][<ffffffc0000ab378>]
__ptrace_may_access+0x164/0x178
[ 2201.337687]<0> (0)[672:android.bg][<ffffffc0000ab8c0>]
ptrace_may_access+0x2c/0x4c
[ 2201.337704]<0> (0)[672:android.bg][<ffffffc000098d48>]
mm_access+0x98/0xe0
[ 2201.337722]<0> (0)[672:android.bg][<ffffffc00020e788>]
proc_mem_open+0x2c/0xa0
[ 2201.337739]<0> (0)[672:android.bg][<ffffffc00020a79c>]
pid_smaps_open+0x48/0x88
[ 2201.337756]<0> (0)[672:android.bg][<ffffffc0001a0c54>]
do_dentry_open+0x178/0x268
[ 2201.337772]<0> (0)[672:android.bg][<ffffffc0001a1e30>]
finish_open+0x30/0x5c
[ 2201.337787]<0> (0)[672:android.bg][<ffffffc0001b12c0>]
do_last.isra.29+0x45c/0xcbc
[ 2201.337802]<0> (0)[672:android.bg][<ffffffc0001b1bd8>]
path_openat.isra.30+0xb8/0x494
[ 2201.337817]<0> (0)[672:android.bg][<ffffffc0001b2028>]
do_filp_open+0x40/0xb4
[ 2201.337834]<0> (0)[672:android.bg][<ffffffc0001a22fc>]
do_sys_open+0x118/0x1f0
[ 2201.337851]<0> (0)[672:android.bg][<ffffffc0001a240c>]
SyS_openat+0x10/0x18
[ 2201.337861]<0> (0)[672:android.bg]---[ end trace e7bf4b0b0cb5766d
]---

Signed-off-by: Mister Oyster <oysterized@gmail.com>
---
 fs/proc/task_mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 29922f578..5368b47ae 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -262,7 +262,7 @@ static int proc_maps_open(struct inode *inode, struct file *file,
 		return -ENOMEM;
 
 	priv->inode = inode;
-	priv->mm = proc_mem_open(inode, PTRACE_MODE_READ);
+	priv->mm = proc_mem_open(inode, PTRACE_MODE_READ_FSCREDS);
 	if (IS_ERR(priv->mm)) {
 		int err = PTR_ERR(priv->mm);
 
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