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

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Date:   Tue, 21 Jun 2022 11:54:41 +0200
From:   Alexey Gladkov <gladkov.alexey@...il.com>
To:     syzbot <syzbot+b4b0d1b35442afbf6fd2@...kaller.appspotmail.com>
Cc:     ebiederm@...ssion.com, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] memory leak in setup_mq_sysctls

On Sun, Jun 19, 2022 at 11:52:25PM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    979086f5e006 Merge tag 'fs.fixes.v5.19-rc3' of git://git.k..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1284331bf00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=c696a83383a77f81
> dashboard link: https://syzkaller.appspot.com/bug?extid=b4b0d1b35442afbf6fd2
> 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=163e740ff00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=132b758bf00000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b4b0d1b35442afbf6fd2@...kaller.appspotmail.com

I'm working on a fix that will remove this memory allocation entirely.

> executing program
> BUG: memory leak
> unreferenced object 0xffff888112fc9200 (size 512):
>   comm "syz-executor237", pid 3648, jiffies 4294970469 (age 12.270s)
>   hex dump (first 32 bytes):
>     ef d3 60 85 ff ff ff ff 0c 9b d2 12 81 88 ff ff  ..`.............
>     04 00 00 00 a4 01 00 00 00 00 00 00 00 00 00 00  ................
>   backtrace:
>     [<ffffffff814b6eb3>] kmemdup+0x23/0x50 mm/util.c:129
>     [<ffffffff82219a9b>] kmemdup include/linux/fortify-string.h:456 [inline]
>     [<ffffffff82219a9b>] setup_mq_sysctls+0x4b/0x1c0 ipc/mq_sysctl.c:89
>     [<ffffffff822197f2>] create_ipc_ns ipc/namespace.c:63 [inline]
>     [<ffffffff822197f2>] copy_ipcs+0x292/0x390 ipc/namespace.c:91
>     [<ffffffff8127de7c>] create_new_namespaces+0xdc/0x4f0 kernel/nsproxy.c:90
>     [<ffffffff8127e89b>] unshare_nsproxy_namespaces+0x9b/0x120 kernel/nsproxy.c:226
>     [<ffffffff8123f92e>] ksys_unshare+0x2fe/0x600 kernel/fork.c:3165
>     [<ffffffff8123fc42>] __do_sys_unshare kernel/fork.c:3236 [inline]
>     [<ffffffff8123fc42>] __se_sys_unshare kernel/fork.c:3234 [inline]
>     [<ffffffff8123fc42>] __x64_sys_unshare+0x12/0x20 kernel/fork.c:3234
>     [<ffffffff845aab45>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>     [<ffffffff845aab45>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>     [<ffffffff8460006a>] entry_SYSCALL_64_after_hwframe+0x46/0xb0
> 
> BUG: memory leak
> unreferenced object 0xffff888112fd5f00 (size 256):
>   comm "syz-executor237", pid 3648, jiffies 4294970469 (age 12.270s)
>   hex dump (first 32 bytes):
>     00 92 fc 12 81 88 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:
>     [<ffffffff816fea1b>] kmalloc include/linux/slab.h:605 [inline]
>     [<ffffffff816fea1b>] kzalloc include/linux/slab.h:733 [inline]
>     [<ffffffff816fea1b>] __register_sysctl_table+0x7b/0x7f0 fs/proc/proc_sysctl.c:1344
>     [<ffffffff82219b7a>] setup_mq_sysctls+0x12a/0x1c0 ipc/mq_sysctl.c:112
>     [<ffffffff822197f2>] create_ipc_ns ipc/namespace.c:63 [inline]
>     [<ffffffff822197f2>] copy_ipcs+0x292/0x390 ipc/namespace.c:91
>     [<ffffffff8127de7c>] create_new_namespaces+0xdc/0x4f0 kernel/nsproxy.c:90
>     [<ffffffff8127e89b>] unshare_nsproxy_namespaces+0x9b/0x120 kernel/nsproxy.c:226
>     [<ffffffff8123f92e>] ksys_unshare+0x2fe/0x600 kernel/fork.c:3165
>     [<ffffffff8123fc42>] __do_sys_unshare kernel/fork.c:3236 [inline]
>     [<ffffffff8123fc42>] __se_sys_unshare kernel/fork.c:3234 [inline]
>     [<ffffffff8123fc42>] __x64_sys_unshare+0x12/0x20 kernel/fork.c:3234
>     [<ffffffff845aab45>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>     [<ffffffff845aab45>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>     [<ffffffff8460006a>] entry_SYSCALL_64_after_hwframe+0x46/0xb0
> 
> BUG: memory leak
> unreferenced object 0xffff888112fbba00 (size 256):
>   comm "syz-executor237", pid 3648, jiffies 4294970469 (age 12.270s)
>   hex dump (first 32 bytes):
>     78 ba fb 12 81 88 ff ff 00 00 00 00 01 00 00 00  x...............
>     01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>   backtrace:
>     [<ffffffff816fef49>] kmalloc include/linux/slab.h:605 [inline]
>     [<ffffffff816fef49>] kzalloc include/linux/slab.h:733 [inline]
>     [<ffffffff816fef49>] new_dir fs/proc/proc_sysctl.c:978 [inline]
>     [<ffffffff816fef49>] get_subdir fs/proc/proc_sysctl.c:1022 [inline]
>     [<ffffffff816fef49>] __register_sysctl_table+0x5a9/0x7f0 fs/proc/proc_sysctl.c:1373
>     [<ffffffff82219b7a>] setup_mq_sysctls+0x12a/0x1c0 ipc/mq_sysctl.c:112
>     [<ffffffff822197f2>] create_ipc_ns ipc/namespace.c:63 [inline]
>     [<ffffffff822197f2>] copy_ipcs+0x292/0x390 ipc/namespace.c:91
>     [<ffffffff8127de7c>] create_new_namespaces+0xdc/0x4f0 kernel/nsproxy.c:90
>     [<ffffffff8127e89b>] unshare_nsproxy_namespaces+0x9b/0x120 kernel/nsproxy.c:226
>     [<ffffffff8123f92e>] ksys_unshare+0x2fe/0x600 kernel/fork.c:3165
>     [<ffffffff8123fc42>] __do_sys_unshare kernel/fork.c:3236 [inline]
>     [<ffffffff8123fc42>] __se_sys_unshare kernel/fork.c:3234 [inline]
>     [<ffffffff8123fc42>] __x64_sys_unshare+0x12/0x20 kernel/fork.c:3234
>     [<ffffffff845aab45>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>     [<ffffffff845aab45>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>     [<ffffffff8460006a>] entry_SYSCALL_64_after_hwframe+0x46/0xb0
> 
> BUG: memory leak
> unreferenced object 0xffff888112fbb900 (size 256):
>   comm "syz-executor237", pid 3648, jiffies 4294970469 (age 12.270s)
>   hex dump (first 32 bytes):
>     78 b9 fb 12 81 88 ff ff 00 00 00 00 01 00 00 00  x...............
>     01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>   backtrace:
>     [<ffffffff816fef49>] kmalloc include/linux/slab.h:605 [inline]
>     [<ffffffff816fef49>] kzalloc include/linux/slab.h:733 [inline]
>     [<ffffffff816fef49>] new_dir fs/proc/proc_sysctl.c:978 [inline]
>     [<ffffffff816fef49>] get_subdir fs/proc/proc_sysctl.c:1022 [inline]
>     [<ffffffff816fef49>] __register_sysctl_table+0x5a9/0x7f0 fs/proc/proc_sysctl.c:1373
>     [<ffffffff82219b7a>] setup_mq_sysctls+0x12a/0x1c0 ipc/mq_sysctl.c:112
>     [<ffffffff822197f2>] create_ipc_ns ipc/namespace.c:63 [inline]
>     [<ffffffff822197f2>] copy_ipcs+0x292/0x390 ipc/namespace.c:91
>     [<ffffffff8127de7c>] create_new_namespaces+0xdc/0x4f0 kernel/nsproxy.c:90
>     [<ffffffff8127e89b>] unshare_nsproxy_namespaces+0x9b/0x120 kernel/nsproxy.c:226
>     [<ffffffff8123f92e>] ksys_unshare+0x2fe/0x600 kernel/fork.c:3165
>     [<ffffffff8123fc42>] __do_sys_unshare kernel/fork.c:3236 [inline]
>     [<ffffffff8123fc42>] __se_sys_unshare kernel/fork.c:3234 [inline]
>     [<ffffffff8123fc42>] __x64_sys_unshare+0x12/0x20 kernel/fork.c:3234
>     [<ffffffff845aab45>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>     [<ffffffff845aab45>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>     [<ffffffff8460006a>] entry_SYSCALL_64_after_hwframe+0x46/0xb0
> 
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@...glegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> syzbot can test patches for this issue, for details see:
> https://goo.gl/tpsmEJ#testing-patches
> 

-- 
Rgrds, legion