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

Alexey Gladkov
2022-06-22T20:07:46Z

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

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);
--
2.33.3