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* [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in hci_send_acl
@ 2023-08-21 16:26 syzbot
  2023-08-31 18:07 ` syzbot
  2024-01-14 14:37 ` syzbot
  0 siblings, 2 replies; 5+ messages in thread
From: syzbot @ 2023-08-21 16:26 UTC (permalink / raw)
  To: johan.hedberg, linux-bluetooth, linux-kernel, luiz.dentz, marcel,
	syzkaller-bugs

Hello,

syzbot found the following issue on:

HEAD commit:    7271b2a53042 Add linux-next specific files for 20230818
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=13404b6ba80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1936af09cdef7dd6
dashboard link: https://syzkaller.appspot.com/bug?extid=a0c80b06ae2cb8895bc4
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13506923a80000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=147569efa80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d81109bc02c1/disk-7271b2a5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4b3bf8e2a4f7/vmlinux-7271b2a5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6404cd473c1e/bzImage-7271b2a5.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a0c80b06ae2cb8895bc4@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in hci_send_acl+0xdf4/0xf30 net/bluetooth/hci_core.c:3228
Read of size 8 at addr ffff888025635618 by task kworker/1:1/27

CPU: 1 PID: 27 Comm: kworker/1:1 Not tainted 6.5.0-rc6-next-20230818-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Workqueue: events l2cap_info_timeout
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xc4/0x620 mm/kasan/report.c:475
 kasan_report+0xda/0x110 mm/kasan/report.c:588
 hci_send_acl+0xdf4/0xf30 net/bluetooth/hci_core.c:3228
 l2cap_send_cmd+0x6dd/0x920 net/bluetooth/l2cap_core.c:977
 l2cap_send_conn_req+0x1e5/0x260 net/bluetooth/l2cap_core.c:1286
 l2cap_start_connection+0x11e/0x420 net/bluetooth/l2cap_core.c:1514
 l2cap_conn_start+0x7ae/0xa40 net/bluetooth/l2cap_core.c:1661
 process_one_work+0x887/0x15d0 kernel/workqueue.c:2630
 process_scheduled_works kernel/workqueue.c:2703 [inline]
 worker_thread+0x8bb/0x1290 kernel/workqueue.c:2784
 kthread+0x33a/0x430 kernel/kthread.c:388
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
 </TASK>

Allocated by task 5046:
 kasan_save_stack+0x33/0x50 mm/kasan/common.c:45
 kasan_set_track+0x25/0x30 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0xa2/0xb0 mm/kasan/common.c:383
 kmalloc include/linux/slab.h:600 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 hci_chan_create+0xa6/0x3a0 net/bluetooth/hci_conn.c:2691
 l2cap_conn_add.part.0+0x1a/0xdf0 net/bluetooth/l2cap_core.c:7841
 l2cap_conn_add include/net/bluetooth/l2cap.h:866 [inline]
 l2cap_chan_connect+0x15b9/0x2140 net/bluetooth/l2cap_core.c:8053
 bt_6lowpan_connect net/bluetooth/6lowpan.c:894 [inline]
 lowpan_control_write+0x3d6/0x730 net/bluetooth/6lowpan.c:1129
 full_proxy_write+0x124/0x190 fs/debugfs/file.c:236
 vfs_write+0x2a4/0xe40 fs/read_write.c:582
 ksys_write+0x12f/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 50:
 kasan_save_stack+0x33/0x50 mm/kasan/common.c:45
 kasan_set_track+0x25/0x30 mm/kasan/common.c:52
 kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:522
 ____kasan_slab_free mm/kasan/common.c:236 [inline]
 ____kasan_slab_free+0x15b/0x1b0 mm/kasan/common.c:200
 kasan_slab_free include/linux/kasan.h:164 [inline]
 slab_free_hook mm/slub.c:1800 [inline]
 slab_free_freelist_hook+0x114/0x1e0 mm/slub.c:1826
 slab_free mm/slub.c:3809 [inline]
 __kmem_cache_free+0xb8/0x2f0 mm/slub.c:3822
 hci_chan_list_flush+0x81/0xf0 net/bluetooth/hci_conn.c:2731
 hci_conn_cleanup net/bluetooth/hci_conn.c:152 [inline]
 hci_conn_del+0x1fc/0xd10 net/bluetooth/hci_conn.c:1140
 hci_abort_conn_sync+0xacb/0xe20 net/bluetooth/hci_sync.c:5432
 abort_conn_sync+0x18e/0x3a0 net/bluetooth/hci_conn.c:2878
 hci_cmd_sync_work+0x1a4/0x3c0 net/bluetooth/hci_sync.c:306
 process_one_work+0x887/0x15d0 kernel/workqueue.c:2630
 process_scheduled_works kernel/workqueue.c:2703 [inline]
 worker_thread+0x8bb/0x1290 kernel/workqueue.c:2784
 kthread+0x33a/0x430 kernel/kthread.c:388
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

Last potentially related work creation:
 kasan_save_stack+0x33/0x50 mm/kasan/common.c:45
 __kasan_record_aux_stack+0xbc/0xd0 mm/kasan/generic.c:492
 kvfree_call_rcu+0x70/0xbe0 kernel/rcu/tree.c:3373
 kernfs_unlink_open_file+0x3b6/0x4b0 fs/kernfs/file.c:633
 kernfs_fop_release+0xec/0x1e0 fs/kernfs/file.c:805
 __fput+0x3f7/0xa70 fs/file_table.c:384
 __fput_sync+0x47/0x50 fs/file_table.c:465
 __do_sys_close fs/open.c:1572 [inline]
 __se_sys_close fs/open.c:1557 [inline]
 __x64_sys_close+0x87/0xf0 fs/open.c:1557
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Second to last potentially related work creation:
 kasan_save_stack+0x33/0x50 mm/kasan/common.c:45
 __kasan_record_aux_stack+0xbc/0xd0 mm/kasan/generic.c:492
 kvfree_call_rcu+0x70/0xbe0 kernel/rcu/tree.c:3373
 kernfs_unlink_open_file+0x3b6/0x4b0 fs/kernfs/file.c:633
 kernfs_fop_release+0xec/0x1e0 fs/kernfs/file.c:805
 __fput+0x3f7/0xa70 fs/file_table.c:384
 __fput_sync+0x47/0x50 fs/file_table.c:465
 __do_sys_close fs/open.c:1572 [inline]
 __se_sys_close fs/open.c:1557 [inline]
 __x64_sys_close+0x87/0xf0 fs/open.c:1557
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff888025635600
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 24 bytes inside of
 freed 128-byte region [ffff888025635600, ffff888025635680)

The buggy address belongs to the physical page:
page:ffffea0000958d40 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x25635
flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000800 ffff888012c418c0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 4500, tgid 4500 (udevd), ts 28013160887, free_ts 27864795775
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x2cf/0x340 mm/page_alloc.c:1536
 prep_new_page mm/page_alloc.c:1543 [inline]
 get_page_from_freelist+0x10d7/0x31b0 mm/page_alloc.c:3219
 __alloc_pages+0x1d0/0x4a0 mm/page_alloc.c:4475
 alloc_pages+0x1a9/0x270 mm/mempolicy.c:2298
 alloc_slab_page mm/slub.c:1870 [inline]
 allocate_slab+0x251/0x380 mm/slub.c:2017
 new_slab mm/slub.c:2070 [inline]
 ___slab_alloc+0x8be/0x1570 mm/slub.c:3223
 __slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3322
 __slab_alloc_node mm/slub.c:3375 [inline]
 slab_alloc_node mm/slub.c:3468 [inline]
 __kmem_cache_alloc_node+0x137/0x350 mm/slub.c:3517
 kmalloc_trace+0x25/0xe0 mm/slab_common.c:1095
 kmalloc include/linux/slab.h:600 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 kernfs_get_open_node fs/kernfs/file.c:572 [inline]
 kernfs_fop_open+0xad1/0xe00 fs/kernfs/file.c:740
 do_dentry_open+0x88b/0x1730 fs/open.c:929
 do_open fs/namei.c:3636 [inline]
 path_openat+0x19af/0x29c0 fs/namei.c:3793
 do_filp_open+0x1de/0x430 fs/namei.c:3820
 do_sys_openat2+0x176/0x1e0 fs/open.c:1422
 do_sys_open fs/open.c:1437 [inline]
 __do_sys_openat fs/open.c:1453 [inline]
 __se_sys_openat fs/open.c:1448 [inline]
 __x64_sys_openat+0x175/0x210 fs/open.c:1448
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1136 [inline]
 free_unref_page_prepare+0x476/0xa40 mm/page_alloc.c:2348
 free_unref_page+0x33/0x3b0 mm/page_alloc.c:2441
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x18b/0x1d0 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x65/0x90 mm/kasan/common.c:305
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook mm/slab.h:762 [inline]
 slab_alloc_node mm/slub.c:3478 [inline]
 slab_alloc mm/slub.c:3486 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3493 [inline]
 kmem_cache_alloc+0x172/0x3b0 mm/slub.c:3502
 getname_flags.part.0+0x50/0x4d0 fs/namei.c:140
 getname_flags include/linux/audit.h:319 [inline]
 getname+0x90/0xe0 fs/namei.c:219
 do_sys_openat2+0x100/0x1e0 fs/open.c:1416
 do_sys_open fs/open.c:1437 [inline]
 __do_sys_openat fs/open.c:1453 [inline]
 __se_sys_openat fs/open.c:1448 [inline]
 __x64_sys_openat+0x175/0x210 fs/open.c:1448
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
 ffff888025635500: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
 ffff888025635580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888025635600: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff888025635680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888025635700: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the bug is already fixed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite bug's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the bug is a duplicate of another bug, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

^ permalink raw reply	[flat|nested] 5+ messages in thread
* [PATCH] Bluetooth: hci_conn: verify connection is to be aborted before doing it
@ 2023-08-25 19:01 Pauli Virtanen
  2023-08-25 19:34 ` [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in hci_send_acl syzbot
  0 siblings, 1 reply; 5+ messages in thread
From: Pauli Virtanen @ 2023-08-25 19:01 UTC (permalink / raw)
  To: linux-bluetooth; +Cc: Pauli Virtanen, syzbot, syzkaller-bugs

There is a race condition where a connection handle is reused, after
hci_abort_conn but before abort_conn_sync is processed in hci_sync. In
this case, hci_abort_conn_sync ends up calling hci_connect_cfm with
success status and then delete the connection, which causes
use-after-free.

Fix by checking abort_reason before calling hci_abort_conn_sync.

Also fix some theoretical UAF / races, where something frees the conn
while hci_abort_conn_sync is working on it.

Fixes: a13f316e90fd ("Bluetooth: hci_conn: Consolidate code for aborting connections")
Reported-by: syzbot+a0c80b06ae2cb8895bc4@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-bluetooth/0000000000005ab984060371583e@google.com/
Signed-off-by: Pauli Virtanen <pav@iki.fi>
---

Notes:
    Not sure how you'd hit this condition in real controller, but syzbot
    does end up calling hci_abort_conn_sync with reason == 0 which then
    causes havoc.

    This can be verified: with a patch that changes abort_conn_sync to

        2874	conn = hci_conn_hash_lookup_handle(hdev, handle);
        2875	if (!conn || WARN_ON(!conn->abort_reason))
        2876		return 0;

    https://syzkaller.appspot.com/text?tag=Patch&x=16eff740680000

    it hits that WARN_ON:

    https://syzkaller.appspot.com/x/log.txt?x=10affb97a80000

#syz test git://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git master

 net/bluetooth/hci_conn.c | 17 ++++++++++++++++-
 net/bluetooth/hci_sync.c |  2 ++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 9d5057cef30a..8622eddb946a 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -2886,12 +2886,25 @@ static int abort_conn_sync(struct hci_dev *hdev, void *data)
 {
 	struct hci_conn *conn;
 	u16 handle = PTR_UINT(data);
+	u8 reason;
+	int err;
+
+	rcu_read_lock();
 
 	conn = hci_conn_hash_lookup_handle(hdev, handle);
+	if (conn) {
+		reason = READ_ONCE(conn->abort_reason);
+		conn = reason ? hci_conn_get(conn) : NULL;
+	}
+
+	rcu_read_unlock();
+
 	if (!conn)
 		return 0;
 
-	return hci_abort_conn_sync(hdev, conn, conn->abort_reason);
+	err = hci_abort_conn_sync(hdev, conn, reason);
+	hci_conn_put(conn);
+	return err;
 }
 
 int hci_abort_conn(struct hci_conn *conn, u8 reason)
@@ -2903,6 +2916,8 @@ int hci_abort_conn(struct hci_conn *conn, u8 reason)
 	 */
 	if (conn->abort_reason)
 		return 0;
+	if (WARN_ON(!reason))
+		reason = HCI_ERROR_UNSPECIFIED;
 
 	bt_dev_dbg(hdev, "handle 0x%2.2x reason 0x%2.2x", conn->handle, reason);
 
diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 9b93653c6197..a93096c5cbfd 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -5375,6 +5375,8 @@ int hci_abort_conn_sync(struct hci_dev *hdev, struct hci_conn *conn, u8 reason)
 	u16 handle = conn->handle;
 	struct hci_conn *c;
 
+	WARN_ON(!reason);
+
 	switch (conn->state) {
 	case BT_CONNECTED:
 	case BT_CONFIG:
-- 
2.41.0


^ permalink raw reply related	[flat|nested] 5+ messages in thread
* [PATCH v2 2/2] Bluetooth: hci_conn: verify connection is to be aborted before doing it
@ 2023-09-30 12:53 Pauli Virtanen
  2023-09-30 13:28 ` [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in hci_send_acl syzbot
  0 siblings, 1 reply; 5+ messages in thread
From: Pauli Virtanen @ 2023-09-30 12:53 UTC (permalink / raw)
  To: linux-bluetooth
  Cc: Pauli Virtanen, syzkaller-bugs, syzbot+a0c80b06ae2cb8895bc4

There is a race condition where a connection handle is reused, after
hci_abort_conn but before abort_conn_sync is processed in hci_sync. In
this case, hci_abort_conn_sync ends up working on the wrong connection,
which can have abort_reason==0, in which case hci_connect_cfm is called
with success status and then connection is deleted, which causes various
use-after-free.

Fix by checking abort_reason is nonzero before calling
hci_abort_conn_sync. If it's zero, then the connection is probably a
different one than we expected and should not be aborted.

Also fix some theoretical UAF / races, where something frees the conn
while hci_abort_conn_sync is working on it.

Fixes: a13f316e90fd ("Bluetooth: hci_conn: Consolidate code for aborting connections")
Reported-by: syzbot+a0c80b06ae2cb8895bc4@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-bluetooth/0000000000005ab984060371583e@google.com/
Signed-off-by: Pauli Virtanen <pav@iki.fi>
---

Notes:
    v2: drop one probably not necessary WARN_ON

    Not sure how you'd hit this condition in real controller, but syzbot
    does end up calling hci_abort_conn_sync with reason == 0 which then
    causes havoc.

    This can be verified: with a patch that changes abort_conn_sync to

        2874	conn = hci_conn_hash_lookup_handle(hdev, handle);
        2875	if (!conn || WARN_ON(!conn->abort_reason))
        2876		return 0;

    https://syzkaller.appspot.com/text?tag=Patch&x=16eff740680000

    it hits that WARN_ON:

    https://syzkaller.appspot.com/x/log.txt?x=10affb97a80000

#syz test git://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git master

 net/bluetooth/hci_conn.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index e62a5f368a51..22de82071e35 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -2901,12 +2901,25 @@ static int abort_conn_sync(struct hci_dev *hdev, void *data)
 {
 	struct hci_conn *conn;
 	u16 handle = PTR_UINT(data);
+	u8 reason;
+	int err;
+
+	rcu_read_lock();
 
 	conn = hci_conn_hash_lookup_handle(hdev, handle);
+	if (conn) {
+		reason = READ_ONCE(conn->abort_reason);
+		conn = reason ? hci_conn_get(conn) : NULL;
+	}
+
+	rcu_read_unlock();
+
 	if (!conn)
 		return 0;
 
-	return hci_abort_conn_sync(hdev, conn, conn->abort_reason);
+	err = hci_abort_conn_sync(hdev, conn, reason);
+	hci_conn_put(conn);
+	return err;
 }
 
 int hci_abort_conn(struct hci_conn *conn, u8 reason)
@@ -2918,6 +2931,8 @@ int hci_abort_conn(struct hci_conn *conn, u8 reason)
 	 */
 	if (conn->abort_reason)
 		return 0;
+	if (WARN_ON(!reason))
+		reason = HCI_ERROR_UNSPECIFIED;
 
 	bt_dev_dbg(hdev, "handle 0x%2.2x reason 0x%2.2x", conn->handle, reason);
 
-- 
2.41.0


^ permalink raw reply related	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2024-01-14 14:37 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2023-08-21 16:26 [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in hci_send_acl syzbot
2023-08-31 18:07 ` syzbot
2024-01-14 14:37 ` syzbot
  -- strict thread matches above, loose matches on Subject: below --
2023-08-25 19:01 [PATCH] Bluetooth: hci_conn: verify connection is to be aborted before doing it Pauli Virtanen
2023-08-25 19:34 ` [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in hci_send_acl syzbot
2023-09-30 12:53 [PATCH v2 2/2] Bluetooth: hci_conn: verify connection is to be aborted before doing it Pauli Virtanen
2023-09-30 13:28 ` [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in hci_send_acl syzbot

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