linux-kernel - Re: [syzbot] memory leak in cap_inode

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Message-ID: <CAJfpegvAPDA-kqCZ8OAqScwfgSoyh5RNQu3rg=LBh6+dFh0hEw@mail.gmail.com>
Date:   Mon, 1 Aug 2022 14:20:29 +0200
From:   Miklos Szeredi <miklos@...redi.hu>
To:     syzbot <syzbot+942d5390db2d9624ced8@...kaller.appspotmail.com>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        marka@...iation.com, phind.uet@...il.com,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>,
        Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [syzbot] memory leak in cap_inode_getsecurity

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
master

On Sun, 31 Jul 2022 at 17:13, syzbot
<syzbot+942d5390db2d9624ced8@...kaller.appspotmail.com> wrote:
>
> syzbot has found a reproducer for the following issue on:
>
> HEAD commit:    6a010258447d Merge tag 'for-linus' of git://git.armlinux.o..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=15883fee080000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=2a1dcc1942e30704
> dashboard link: https://syzkaller.appspot.com/bug?extid=942d5390db2d9624ced8
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1568846a080000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10f5e536080000
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+942d5390db2d9624ced8@...kaller.appspotmail.com
>
> executing program
> BUG: memory leak
> unreferenced object 0xffff88810f0ac060 (size 32):
>   comm "syz-executor240", pid 3622, jiffies 4294961303 (age 14.040s)
>   hex dump (first 32 bytes):
>     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>   backtrace:
>     [<ffffffff814c6ecd>] __do_krealloc mm/slab_common.c:1185 [inline]
>     [<ffffffff814c6ecd>] krealloc+0x4d/0xb0 mm/slab_common.c:1218
>     [<ffffffff8162625c>] vfs_getxattr_alloc+0x13c/0x1c0 fs/xattr.c:379
>     [<ffffffff822374b2>] cap_inode_getsecurity+0xb2/0x500 security/commoncap.c:400
>     [<ffffffff8223d88c>] security_inode_getsecurity+0x7c/0xb0 security/security.c:1441
>     [<ffffffff81625a0a>] xattr_getsecurity fs/xattr.c:327 [inline]
>     [<ffffffff81625a0a>] vfs_getxattr+0x22a/0x290 fs/xattr.c:423
>     [<ffffffff81c0ab02>] ovl_xattr_get+0x62/0xa0 fs/overlayfs/inode.c:404
>     [<ffffffff81624742>] __vfs_getxattr+0x72/0xa0 fs/xattr.c:401
>     [<ffffffff82236f52>] cap_inode_need_killpriv+0x22/0x40 security/commoncap.c:301
>     [<ffffffff8223d773>] security_inode_need_killpriv+0x23/0x60 security/security.c:1419
>     [<ffffffff8161074e>] dentry_needs_remove_privs fs/inode.c:1992 [inline]
>     [<ffffffff8161074e>] dentry_needs_remove_privs+0x4e/0xa0 fs/inode.c:1982
>     [<ffffffff815cfead>] do_truncate+0x7d/0x130 fs/open.c:57
>     [<ffffffff815d0169>] vfs_truncate+0x209/0x240 fs/open.c:111
>     [<ffffffff815d0268>] do_sys_truncate.part.0+0xc8/0xe0 fs/open.c:134
>     [<ffffffff815d0303>] do_sys_truncate fs/open.c:128 [inline]
>     [<ffffffff815d0303>] __do_sys_truncate fs/open.c:146 [inline]
>     [<ffffffff815d0303>] __se_sys_truncate fs/open.c:144 [inline]
>     [<ffffffff815d0303>] __x64_sys_truncate+0x33/0x50 fs/open.c:144
>     [<ffffffff845b1955>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>     [<ffffffff845b1955>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>     [<ffffffff84600087>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
>
>

View attachment "vfs_getxattr_alloc-dont-allocate-buf-on-failure.patch" of type "text/x-patch" (384 bytes)