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Date: Mon, 18 Mar 2019 10:23:53 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Zhang Yu <zhangyu31@...du.com>,
Li RongQing <lirongqing@...du.com>,
Evgeniy Polyakov <zbr@...emap.net>,
"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 5.0 01/43] connector: fix unsafe usage of ->real_parent
5.0-stable review patch. If anyone has any objections, please let me know.
------------------
From: Li RongQing <lirongqing@...du.com>
[ Upstream commit 6d2b0f02f5a07a4bf02e4cbc90d7eaa85cac2986 ]
proc_exit_connector() uses ->real_parent lockless. This is not
safe that its parent can go away at any moment, so use RCU to
protect it, and ensure that this task is not released.
[ 747.624551] ==================================================================
[ 747.632946] BUG: KASAN: use-after-free in proc_exit_connector+0x1f7/0x310
[ 747.640686] Read of size 4 at addr ffff88a0276988e0 by task sshd/2882
[ 747.648032]
[ 747.649804] CPU: 11 PID: 2882 Comm: sshd Tainted: G E 4.19.26-rc2 #11
[ 747.658629] Hardware name: IBM x3550M4 -[7914OFV]-/00AM544, BIOS -[D7E142BUS-1.71]- 07/31/2014
[ 747.668419] Call Trace:
[ 747.671269] dump_stack+0xf0/0x19b
[ 747.675186] ? show_regs_print_info+0x5/0x5
[ 747.679988] ? kmsg_dump_rewind_nolock+0x59/0x59
[ 747.685302] print_address_description+0x6a/0x270
[ 747.691162] kasan_report+0x258/0x380
[ 747.695835] ? proc_exit_connector+0x1f7/0x310
[ 747.701402] proc_exit_connector+0x1f7/0x310
[ 747.706767] ? proc_coredump_connector+0x2d0/0x2d0
[ 747.712715] ? _raw_write_unlock_irq+0x29/0x50
[ 747.718270] ? _raw_write_unlock_irq+0x29/0x50
[ 747.723820] ? ___preempt_schedule+0x16/0x18
[ 747.729193] ? ___preempt_schedule+0x16/0x18
[ 747.734574] do_exit+0xa11/0x14f0
[ 747.738880] ? mm_update_next_owner+0x590/0x590
[ 747.744525] ? debug_show_all_locks+0x3c0/0x3c0
[ 747.761448] ? ktime_get_coarse_real_ts64+0xeb/0x1c0
[ 747.767589] ? lockdep_hardirqs_on+0x1a6/0x290
[ 747.773154] ? check_chain_key+0x139/0x1f0
[ 747.778345] ? check_flags.part.35+0x240/0x240
[ 747.783908] ? __lock_acquire+0x2300/0x2300
[ 747.789171] ? _raw_spin_unlock_irqrestore+0x59/0x70
[ 747.795316] ? _raw_spin_unlock_irqrestore+0x59/0x70
[ 747.801457] ? do_raw_spin_unlock+0x10f/0x1e0
[ 747.806914] ? do_raw_spin_trylock+0x120/0x120
[ 747.812481] ? preempt_count_sub+0x14/0xc0
[ 747.817645] ? _raw_spin_unlock+0x2e/0x50
[ 747.822708] ? __handle_mm_fault+0x12db/0x1fa0
[ 747.828367] ? __pmd_alloc+0x2d0/0x2d0
[ 747.833143] ? check_noncircular+0x50/0x50
[ 747.838309] ? match_held_lock+0x7f/0x340
[ 747.843380] ? check_noncircular+0x50/0x50
[ 747.848561] ? handle_mm_fault+0x21a/0x5f0
[ 747.853730] ? check_flags.part.35+0x240/0x240
[ 747.859290] ? check_chain_key+0x139/0x1f0
[ 747.864474] ? __do_page_fault+0x40f/0x760
[ 747.869655] ? __audit_syscall_entry+0x4b/0x1f0
[ 747.875319] ? syscall_trace_enter+0x1d5/0x7b0
[ 747.880877] ? trace_raw_output_preemptirq_template+0x90/0x90
[ 747.887895] ? trace_raw_output_sys_exit+0x80/0x80
[ 747.893860] ? up_read+0x3b/0x90
[ 747.898142] ? stop_critical_timings+0x260/0x260
[ 747.903909] do_group_exit+0xe0/0x1c0
[ 747.908591] ? __x64_sys_exit+0x30/0x30
[ 747.913460] ? trace_raw_output_preemptirq_template+0x90/0x90
[ 747.920485] ? tracer_hardirqs_on+0x270/0x270
[ 747.925956] __x64_sys_exit_group+0x28/0x30
[ 747.931214] do_syscall_64+0x117/0x400
[ 747.935988] ? syscall_return_slowpath+0x2f0/0x2f0
[ 747.941931] ? trace_hardirqs_off_thunk+0x1a/0x1c
[ 747.947788] ? trace_hardirqs_on_caller+0x1d0/0x1d0
[ 747.953838] ? lockdep_sys_exit+0x16/0x8e
[ 747.958915] ? trace_hardirqs_off_thunk+0x1a/0x1c
[ 747.964784] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 747.971021] RIP: 0033:0x7f572f154c68
[ 747.975606] Code: Bad RIP value.
[ 747.979791] RSP: 002b:00007ffed2dfaa58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
[ 747.989324] RAX: ffffffffffffffda RBX: 00007f572f431840 RCX: 00007f572f154c68
[ 747.997910] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001
[ 748.006495] RBP: 0000000000000001 R08: 00000000000000e7 R09: fffffffffffffee0
[ 748.015079] R10: 00007f572f4387e8 R11: 0000000000000246 R12: 00007f572f431840
[ 748.023664] R13: 000055a7f90f2c50 R14: 000055a7f96e2310 R15: 000055a7f96e2310
[ 748.032287]
[ 748.034509] Allocated by task 2300:
[ 748.038982] kasan_kmalloc+0xa0/0xd0
[ 748.043562] kmem_cache_alloc_node+0xf5/0x2e0
[ 748.049018] copy_process+0x1781/0x4790
[ 748.053884] _do_fork+0x166/0x9a0
[ 748.058163] do_syscall_64+0x117/0x400
[ 748.062943] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 748.069180]
[ 748.071405] Freed by task 15395:
[ 748.075591] __kasan_slab_free+0x130/0x180
[ 748.080752] kmem_cache_free+0xc2/0x310
[ 748.085619] free_task+0xea/0x130
[ 748.089901] __put_task_struct+0x177/0x230
[ 748.095063] finish_task_switch+0x51b/0x5d0
[ 748.100315] __schedule+0x506/0xfa0
[ 748.104791] schedule+0xca/0x260
[ 748.108978] futex_wait_queue_me+0x27e/0x420
[ 748.114333] futex_wait+0x251/0x550
[ 748.118814] do_futex+0x75b/0xf80
[ 748.123097] __x64_sys_futex+0x231/0x2a0
[ 748.128065] do_syscall_64+0x117/0x400
[ 748.132835] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 748.139066]
[ 748.141289] The buggy address belongs to the object at ffff88a027698000
[ 748.141289] which belongs to the cache task_struct of size 12160
[ 748.156589] The buggy address is located 2272 bytes inside of
[ 748.156589] 12160-byte region [ffff88a027698000, ffff88a02769af80)
[ 748.171114] The buggy address belongs to the page:
[ 748.177055] page:ffffea00809da600 count:1 mapcount:0 mapping:ffff888107d01e00 index:0x0 compound_mapcount: 0
[ 748.189136] flags: 0x57ffffc0008100(slab|head)
[ 748.194688] raw: 0057ffffc0008100 ffffea00809a3200 0000000300000003 ffff888107d01e00
[ 748.204424] raw: 0000000000000000 0000000000020002 00000001ffffffff 0000000000000000
[ 748.214146] page dumped because: kasan: bad access detected
[ 748.220976]
[ 748.223197] Memory state around the buggy address:
[ 748.229128] ffff88a027698780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 748.238271] ffff88a027698800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 748.247414] >ffff88a027698880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 748.256564] ^
[ 748.264267] ffff88a027698900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 748.273493] ffff88a027698980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 748.282630] ==================================================================
Fixes: b086ff87251b4a4 ("connector: add parent pid and tgid to coredump and exit events")
Signed-off-by: Zhang Yu <zhangyu31@...du.com>
Signed-off-by: Li RongQing <lirongqing@...du.com>
Acked-by: Evgeniy Polyakov <zbr@...emap.net>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
drivers/connector/cn_proc.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)
--- a/drivers/connector/cn_proc.c
+++ b/drivers/connector/cn_proc.c
@@ -250,6 +250,7 @@ void proc_coredump_connector(struct task
{
struct cn_msg *msg;
struct proc_event *ev;
+ struct task_struct *parent;
__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
if (atomic_read(&proc_event_num_listeners) < 1)
@@ -262,8 +263,14 @@ void proc_coredump_connector(struct task
ev->what = PROC_EVENT_COREDUMP;
ev->event_data.coredump.process_pid = task->pid;
ev->event_data.coredump.process_tgid = task->tgid;
- ev->event_data.coredump.parent_pid = task->real_parent->pid;
- ev->event_data.coredump.parent_tgid = task->real_parent->tgid;
+
+ rcu_read_lock();
+ if (pid_alive(task)) {
+ parent = rcu_dereference(task->real_parent);
+ ev->event_data.coredump.parent_pid = parent->pid;
+ ev->event_data.coredump.parent_tgid = parent->tgid;
+ }
+ rcu_read_unlock();
memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
msg->ack = 0; /* not used */
@@ -276,6 +283,7 @@ void proc_exit_connector(struct task_str
{
struct cn_msg *msg;
struct proc_event *ev;
+ struct task_struct *parent;
__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
if (atomic_read(&proc_event_num_listeners) < 1)
@@ -290,8 +298,14 @@ void proc_exit_connector(struct task_str
ev->event_data.exit.process_tgid = task->tgid;
ev->event_data.exit.exit_code = task->exit_code;
ev->event_data.exit.exit_signal = task->exit_signal;
- ev->event_data.exit.parent_pid = task->real_parent->pid;
- ev->event_data.exit.parent_tgid = task->real_parent->tgid;
+
+ rcu_read_lock();
+ if (pid_alive(task)) {
+ parent = rcu_dereference(task->real_parent);
+ ev->event_data.exit.parent_pid = parent->pid;
+ ev->event_data.exit.parent_tgid = parent->tgid;
+ }
+ rcu_read_unlock();
memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
msg->ack = 0; /* not used */
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