vsprintf: Turn kptr_restrict off by default

kptr_restrict has been triggering bugs in apps such as perf, and it also makes
the system less useful by default, so turn it off by default.

This is how we generally handle security features that remove functionality,
such as firewall code or SELinux - they have to be configured and activated
from user-space.

Distributions can turn kptr_restrict on again via this line in
/etc/sysctrl.conf:

kernel.kptr_restrict = 1

( Also mark the variable __read_mostly while at it, as it's typically modified
  only once per bootup, or not at all. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index bc0ac6b333d..dfd60192bc2 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -797,7 +797,7 @@ char *uuid_string(char *buf, char *end, const u8 *addr,
         return string(buf, end, uuid, spec);
 }
 
-int kptr_restrict = 1;
+int kptr_restrict __read_mostly;
 
 /*
  * Show a '%p' thing.  A kernel extension is that the '%p' is followed