linux-kernel - Re: [PATCH] ceph: fix memory leak in __ceph

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Message-Id: <4A628342-B33B-4730-889F-3D8F62037CB1@redhat.com>
Date:   Fri, 28 Apr 2017 21:52:26 +0800
From:   "Yan, Zheng" <zyan@...hat.com>
To:     Luis Henriques <lhenriques@...e.com>
Cc:     Sage Weil <sage@...hat.com>, Ilya Dryomov <idryomov@...il.com>,
        ceph-devel <ceph-devel@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        stable@...r.kernel.org
Subject: Re: [PATCH] ceph: fix memory leak in __ceph_setxattr()


> On 28 Apr 2017, at 18:14, Luis Henriques <lhenriques@...e.com> wrote:
> 
> The ceph_inode_xattr needs to be released when removing an xattr.  Easily
> reproducible running the 'generic/020' test from xfstests or simply by
> doing:
> 
>  attr -s attr0 -V 0 /mnt/test && attr -r attr0 /mnt/test
> 
> While there, also fix the error path.
> 
> Here's the kmemleak splat:
> 
> unreferenced object 0xffff88001f86fbc0 (size 64):
>  comm "attr", pid 244, jiffies 4294904246 (age 98.464s)
>  hex dump (first 32 bytes):
>    40 fa 86 1f 00 88 ff ff 80 32 38 1f 00 88 ff ff  @........28.....
>    00 01 00 00 00 00 ad de 00 02 00 00 00 00 ad de  ................
>  backtrace:
>    [<ffffffff81560199>] kmemleak_alloc+0x49/0xa0
>    [<ffffffff810f3e5b>] kmem_cache_alloc+0x9b/0xf0
>    [<ffffffff812b157e>] __ceph_setxattr+0x17e/0x820
>    [<ffffffff812b1c57>] ceph_set_xattr_handler+0x37/0x40
>    [<ffffffff8111fb4b>] __vfs_removexattr+0x4b/0x60
>    [<ffffffff8111fd37>] vfs_removexattr+0x77/0xd0
>    [<ffffffff8111fdd1>] removexattr+0x41/0x60
>    [<ffffffff8111fe65>] path_removexattr+0x75/0xa0
>    [<ffffffff81120aeb>] SyS_lremovexattr+0xb/0x10
>    [<ffffffff81564b20>] entry_SYSCALL_64_fastpath+0x13/0x94
>    [<ffffffffffffffff>] 0xffffffffffffffff
> 
> Cc: stable@...r.kernel.org
> Signed-off-by: Luis Henriques <lhenriques@...e.com>
> ---
> fs/ceph/xattr.c | 3 +++
> 1 file changed, 3 insertions(+)
> 
> diff --git a/fs/ceph/xattr.c b/fs/ceph/xattr.c
> index febc28f9e2c2..75267cdd5dfd 100644
> --- a/fs/ceph/xattr.c
> +++ b/fs/ceph/xattr.c
> @@ -392,6 +392,7 @@ static int __set_xattr(struct ceph_inode_info *ci,
> 
> 	if (update_xattr) {
> 		int err = 0;
> +
> 		if (xattr && (flags & XATTR_CREATE))
> 			err = -EEXIST;
> 		else if (!xattr && (flags & XATTR_REPLACE))
> @@ -399,12 +400,14 @@ static int __set_xattr(struct ceph_inode_info *ci,
> 		if (err) {
> 			kfree(name);
> 			kfree(val);
> +			kfree(*newxattr);
> 			return err;
> 		}
> 		if (update_xattr < 0) {
> 			if (xattr)
> 				__remove_xattr(ci, xattr);
> 			kfree(name);
> +			kfree(*newxattr);
> 			return 0;
> 		}
> 	}

Applied, thanks

Yan, Zheng