linux-kernel - [PATCH 4.9 024/108] kernel/ucount.c: mark user_header with kmemleak

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Date:   Thu, 15 Jun 2017 19:52:30 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, "Luis R. Rodriguez" <mcgrof@...nel.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Kees Cook <keescook@...omium.org>,
        Nikolay Borisov <n.borisov.lkml@...il.com>,
        Serge Hallyn <serge@...lyn.com>, Jan Kara <jack@...e.cz>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.9 024/108] kernel/ucount.c: mark user_header with kmemleak_ignore()

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Luis R. Rodriguez" <mcgrof@...nel.org>


[ Upstream commit ed5bd7dc88edf4a4a9c67130742b1b59aa017a5f ]

The user_header gets caught by kmemleak with the following splat as
missing a free:

  unreferenced object 0xffff99667a733d80 (size 96):
  comm "swapper/0", pid 1, jiffies 4294892317 (age 62191.468s)
  hex dump (first 32 bytes):
    a0 b6 92 b4 ff ff ff ff 00 00 00 00 01 00 00 00  ................
    01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
     kmemleak_alloc+0x4a/0xa0
     __kmalloc+0x144/0x260
     __register_sysctl_table+0x54/0x5e0
     register_sysctl+0x1b/0x20
     user_namespace_sysctl_init+0x17/0x34
     do_one_initcall+0x52/0x1a0
     kernel_init_freeable+0x173/0x200
     kernel_init+0xe/0x100
     ret_from_fork+0x2c/0x40

The BUG_ON()s are intended to crash so no need to clean up after
ourselves on error there.  This is also a kernel/ subsys_init() we don't
need a respective exit call here as this is never modular, so just white
list it.

Link: http://lkml.kernel.org/r/20170203211404.31458-1-mcgrof@kernel.org
Signed-off-by: Luis R. Rodriguez <mcgrof@...nel.org>
Cc: Eric W. Biederman <ebiederm@...ssion.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Nikolay Borisov <n.borisov.lkml@...il.com>
Cc: Serge Hallyn <serge@...lyn.com>
Cc: Jan Kara <jack@...e.cz>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 kernel/ucount.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -231,11 +231,10 @@ static __init int user_namespace_sysctl_
 	 * properly.
 	 */
 	user_header = register_sysctl("user", empty);
+	kmemleak_ignore(user_header);
 	BUG_ON(!user_header);
 	BUG_ON(!setup_userns_sysctls(&init_user_ns));
 #endif
 	return 0;
 }
 subsys_initcall(user_namespace_sysctl_init);
-
-