[Devel] [PATCH RHEL7 COMMIT] ms/mm: prevent KASAN false positives in kmemleak

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-514.16.1.vz7.32.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-514.16.1.vz7.32.5
------>
commit bf0630292fd57923fac16db5d73c974b8633ca5d
Author: Dmitry Vyukov <dvyukov at google.com>
Date:   Wed May 31 17:41:32 2017 +0400

    ms/mm: prevent KASAN false positives in kmemleak
    
    commit 5c335fe020ea287b2b49cc4dfca9f6756b88bb71 upstream.
    
    When kmemleak dumps contents of leaked objects it reads whole objects
    regardless of user-requested size.  This upsets KASAN.  Disable KASAN
    checks around object dump.
    
    Link: http://lkml.kernel.org/r/1466617631-68387-1-git-send-email-dvyukov@google.com
    Signed-off-by: Dmitry Vyukov <dvyukov at google.com>
    Acked-by: Catalin Marinas <catalin.marinas at arm.com>
    Cc: Andrey Ryabinin <ryabinin.a.a at gmail.com>
    Cc: Alexander Potapenko <glider at google.com>
    Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
    
    Found during investigating https://jira.sw.ru/browse/PSBM-66617
    Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
---
 mm/kmemleak.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index ea54d1b..db297cd 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -299,6 +299,8 @@ static void hex_dump_object(struct seq_file *seq,
 		min(object->size, (size_t)(HEX_MAX_LINES * HEX_ROW_SIZE));
 
 	seq_printf(seq, "  hex dump (first %d bytes):\n", len);
+	kasan_disable_current();
+
 	for (i = 0; i < len; i += HEX_ROW_SIZE) {
 		int linelen = min(remaining, HEX_ROW_SIZE);
 
@@ -308,6 +310,7 @@ static void hex_dump_object(struct seq_file *seq,
 				   HEX_ASCII);
 		seq_printf(seq, "    %s\n", linebuf);
 	}
+	kasan_enable_current();
 }
 
 /*