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Message-ID: <20250324132427.922495-1-dmantipov@yandex.ru>
Date: Mon, 24 Mar 2025 16:24:27 +0300
From: Dmitry Antipov <dmantipov@...dex.ru>
To: Arve Hjønnevåg <arve@...roid.com>,
Todd Kjos <tkjos@...roid.com>,
Martijn Coenen <maco@...roid.com>,
Joel Fernandes <joel@...lfernandes.org>,
Christian Brauner <brauner@...nel.org>,
Carlos Llamas <cmllamas@...gle.com>,
Suren Baghdasaryan <surenb@...gle.com>
Cc: Colin Ian King <colin.i.king@...il.com>,
linux-kernel@...r.kernel.org,
lvc-project@...uxtesting.org,
Dmitry Antipov <dmantipov@...dex.ru>,
syzbot+353d7b75658a95aa955a@...kaller.appspotmail.com
Subject: [PATCH] binder: fix use-after-free in binderfs_evict_inode()
Running 'stress-ng --binderfs 16 --timeout 300' under KASAN-enabled
kernel, I've noticed the following:
BUG: KASAN: slab-use-after-free in binderfs_evict_inode+0x1de/0x2d0
Write of size 8 at addr ffff88807379bc08 by task stress-ng-binde/1699
CPU: 0 UID: 0 PID: 1699 Comm: stress-ng-binde Not tainted 6.14.0-rc7-g586de92313fc-dirty #13
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x1c2/0x2a0
? __pfx_dump_stack_lvl+0x10/0x10
? __pfx__printk+0x10/0x10
? __pfx_lock_release+0x10/0x10
? __virt_addr_valid+0x18c/0x540
? __virt_addr_valid+0x469/0x540
print_report+0x155/0x840
? __virt_addr_valid+0x18c/0x540
? __virt_addr_valid+0x469/0x540
? __phys_addr+0xba/0x170
? binderfs_evict_inode+0x1de/0x2d0
kasan_report+0x147/0x180
? binderfs_evict_inode+0x1de/0x2d0
binderfs_evict_inode+0x1de/0x2d0
? __pfx_binderfs_evict_inode+0x10/0x10
evict+0x524/0x9f0
? __pfx_lock_release+0x10/0x10
? __pfx_evict+0x10/0x10
? do_raw_spin_unlock+0x4d/0x210
? _raw_spin_unlock+0x28/0x50
? iput+0x697/0x9b0
__dentry_kill+0x209/0x660
? shrink_kill+0x8d/0x2c0
shrink_kill+0xa9/0x2c0
shrink_dentry_list+0x2e0/0x5e0
shrink_dcache_parent+0xa2/0x2c0
? __pfx_shrink_dcache_parent+0x10/0x10
? __pfx_lock_release+0x10/0x10
? __pfx_do_raw_spin_lock+0x10/0x10
do_one_tree+0x23/0xe0
shrink_dcache_for_umount+0xa0/0x170
generic_shutdown_super+0x67/0x390
kill_litter_super+0x76/0xb0
binderfs_kill_super+0x44/0x90
deactivate_locked_super+0xb9/0x130
cleanup_mnt+0x422/0x4c0
? lockdep_hardirqs_on+0x9d/0x150
task_work_run+0x1d2/0x260
? __pfx_task_work_run+0x10/0x10
resume_user_mode_work+0x52/0x60
syscall_exit_to_user_mode+0x9a/0x120
do_syscall_64+0x103/0x210
? asm_sysvec_apic_timer_interrupt+0x1a/0x20
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0xcac57b
Code: c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 f3 0f 1e fa 31 f6 e9 05 00 00 00 0f 1f 44 00 00 f3 0f 1e fa b8
RSP: 002b:00007ffecf4226a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007ffecf422720 RCX: 0000000000cac57b
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007ffecf422850
RBP: 00007ffecf422850 R08: 0000000028d06ab1 R09: 7fffffffffffffff
R10: 3fffffffffffffff R11: 0000000000000246 R12: 00007ffecf422718
R13: 00007ffecf422710 R14: 00007f478f87b658 R15: 00007ffecf422830
</TASK>
Allocated by task 1705:
kasan_save_track+0x3e/0x80
__kasan_kmalloc+0x8f/0xa0
__kmalloc_cache_noprof+0x213/0x3e0
binderfs_binder_device_create+0x183/0xa80
binder_ctl_ioctl+0x138/0x190
__x64_sys_ioctl+0x120/0x1b0
do_syscall_64+0xf6/0x210
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 1705:
kasan_save_track+0x3e/0x80
kasan_save_free_info+0x46/0x50
__kasan_slab_free+0x62/0x70
kfree+0x194/0x440
evict+0x524/0x9f0
do_unlinkat+0x390/0x5b0
__x64_sys_unlink+0x47/0x50
do_syscall_64+0xf6/0x210
entry_SYSCALL_64_after_hwframe+0x77/0x7f
This 'stress-ng' workload causes the concurrent deletions from
'binder_devices' and so requires full-featured synchronization
to prevent list corruption.
I've found this issue independently but pretty sure that syzbot did
the same, so Reported-by: and Closes: should be applicable here as well.
Reported-by: syzbot+353d7b75658a95aa955a@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=353d7b75658a95aa955a
Fixes: e77aff5528a18 ("binderfs: fix use-after-free in binder_devices")
Signed-off-by: Dmitry Antipov <dmantipov@...dex.ru>
---
drivers/android/binder.c | 15 +++++++++++++--
drivers/android/binder_internal.h | 8 ++++++--
drivers/android/binderfs.c | 2 +-
3 files changed, 20 insertions(+), 5 deletions(-)
diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 76052006bd87..bf79a0e339fe 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -79,6 +79,8 @@ static HLIST_HEAD(binder_deferred_list);
static DEFINE_MUTEX(binder_deferred_lock);
static HLIST_HEAD(binder_devices);
+static DEFINE_SPINLOCK(binder_devices_lock);
+
static HLIST_HEAD(binder_procs);
static DEFINE_MUTEX(binder_procs_lock);
@@ -6929,7 +6931,16 @@ const struct binder_debugfs_entry binder_debugfs_entries[] = {
void binder_add_device(struct binder_device *device)
{
+ spin_lock(&binder_devices_lock);
hlist_add_head(&device->hlist, &binder_devices);
+ spin_unlock(&binder_devices_lock);
+}
+
+void binder_remove_device(struct binder_device *device)
+{
+ spin_lock(&binder_devices_lock);
+ hlist_del_init(&device->hlist);
+ spin_unlock(&binder_devices_lock);
}
static int __init init_binder_device(const char *name)
@@ -6956,7 +6967,7 @@ static int __init init_binder_device(const char *name)
return ret;
}
- hlist_add_head(&binder_device->hlist, &binder_devices);
+ binder_add_device(binder_device);
return ret;
}
@@ -7018,7 +7029,7 @@ static int __init binder_init(void)
err_init_binder_device_failed:
hlist_for_each_entry_safe(device, tmp, &binder_devices, hlist) {
misc_deregister(&device->miscdev);
- hlist_del(&device->hlist);
+ binder_remove_device(device);
kfree(device);
}
diff --git a/drivers/android/binder_internal.h b/drivers/android/binder_internal.h
index e4eb8357989c..c5d68c1d3780 100644
--- a/drivers/android/binder_internal.h
+++ b/drivers/android/binder_internal.h
@@ -584,9 +584,13 @@ struct binder_object {
/**
* Add a binder device to binder_devices
* @device: the new binder device to add to the global list
- *
- * Not reentrant as the list is not protected by any locks
*/
void binder_add_device(struct binder_device *device);
+/**
+ * Remove a binder device to binder_devices
+ * @device: the binder device to remove from the global list
+ */
+void binder_remove_device(struct binder_device *device);
+
#endif /* _LINUX_BINDER_INTERNAL_H */
diff --git a/drivers/android/binderfs.c b/drivers/android/binderfs.c
index 94c6446604fc..44d430c4ebef 100644
--- a/drivers/android/binderfs.c
+++ b/drivers/android/binderfs.c
@@ -274,7 +274,7 @@ static void binderfs_evict_inode(struct inode *inode)
mutex_unlock(&binderfs_minors_mutex);
if (refcount_dec_and_test(&device->ref)) {
- hlist_del_init(&device->hlist);
+ binder_remove_device(device);
kfree(device->context.name);
kfree(device);
}
--
2.49.0
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