Re: [PATCH] ipc: Free mq_sysctls if ipc namespace creation failed

Eric W. Biederman
2022-06-22T22:56:06Z

Alexey Gladkov <legion@kernel.org> writes:

> The problem that Dmitry Vyukov pointed out is that if setup_ipc_sysctls fails,
> mq_sysctls must be freed before return.

Can we get a tested-by from syzbot?

It would be nice to confirm that this bug is the one syzbot was seeing.

Thank you,
Eric

> 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
>
> Reported-by: syzbot+b4b0d1b35442afbf6fd2@syzkaller.appspotmail.com
> Signed-off-by: Alexey Gladkov <legion@kernel.org>
> ---
> ipc/namespace.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/ipc/namespace.c b/ipc/namespace.c
> index 754f3237194a..e1fcaedba4fa 100644
> --- a/ipc/namespace.c
> +++ b/ipc/namespace.c
> @@ -64,7 +64,7 @@ static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
> goto fail_put;
>
> if (!setup_ipc_sysctls(ns))
> - goto fail_put;
> + goto fail_mq;
>
> sem_init_ns(ns);
> msg_init_ns(ns);
> @@ -72,6 +72,9 @@ static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
>
> return ns;
>
> +fail_mq:
> + retire_mq_sysctls(ns);
> +
> fail_put:
> put_user_ns(ns->user_ns);
> ns_free_inum(&ns->ns);