[syzbot] [bluetooth?] KASAN: slab-out-of-bounds Read in create_monitor_event

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f291209eca5e Merge tag 'net-6.6-rc5' of git://git.kernel.o..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=11011862680000
kernel config: https://syzkaller.appspot.com/x/.config?x=7a5682d32a74b423
dashboard link: https://syzkaller.appspot.com/bug?extid=c90849c50ed209d77689
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14d8746e680000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1388dbae680000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c35c46fb9748/disk-f291209e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f0cdf2349ddb/vmlinux-f291209e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2f4c7b7ed7c4/bzImage-f291209e.xz

The issue was bisected to:

commit dcda165706b9fbfd685898d46a6749d7d397e0c0
Author: Luiz Augusto von Dentz <luiz.vo...@intel.com>
Date: Fri Sep 15 21:42:27 2023 +0000

Bluetooth: hci_core: Fix build warnings

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1279df95680000
final oops: https://syzkaller.appspot.com/x/report.txt?x=1179df95680000
console output: https://syzkaller.appspot.com/x/log.txt?x=1679df95680000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c90849...@syzkaller.appspotmail.com
Fixes: dcda165706b9 ("Bluetooth: hci_core: Fix build warnings")

==================================================================
BUG: KASAN: slab-out-of-bounds in create_monitor_event+0x88d/0x930 net/bluetooth/hci_sock.c:491
Read of size 8 at addr ffff88801e5458c7 by task syz-executor191/5038

CPU: 0 PID: 5038 Comm: syz-executor191 Not tainted 6.6.0-rc4-syzkaller-00158-gf291209eca5e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0x163/0x540 mm/kasan/report.c:475
kasan_report+0x175/0x1b0 mm/kasan/report.c:588
create_monitor_event+0x88d/0x930 net/bluetooth/hci_sock.c:491
send_monitor_replay+0x7a/0x5d0 net/bluetooth/hci_sock.c:723
hci_sock_bind+0x85c/0x1140 net/bluetooth/hci_sock.c:1387
__sys_bind+0x23a/0x2e0 net/socket.c:1849
__do_sys_bind net/socket.c:1860 [inline]
__se_sys_bind net/socket.c:1858 [inline]
__x64_sys_bind+0x7a/0x90 net/socket.c:1858
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fa90faa64f9
Code: 48 83 c4 28 c3 e8 17 19 00 00 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc6a6f17b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000031
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007fa90faa64f9
RDX: 0000000000000006 RSI: 0000000020000000 RDI: 0000000000000004
RBP: 0000000000000003 R08: 000000ff00ffb650 R09: 000000ff00ffb650
R10: 0000000000000000 R11: 0000000000000246 R12: 000055555604a370
R13: 0000000000000072 R14: 00007fa90fb2a5b0 R15: 0000000000000001
</TASK>

Allocated by task 5038:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:374 [inline]
__kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:383
kasan_kmalloc include/linux/kasan.h:198 [inline]
__do_kmalloc_node mm/slab_common.c:1023 [inline]
__kmalloc_node_track_caller+0xb6/0x230 mm/slab_common.c:1043
kvasprintf+0xdf/0x190 lib/kasprintf.c:25
kobject_set_name_vargs+0x61/0x120 lib/kobject.c:272
dev_set_name+0xd5/0x120 drivers/base/core.c:3427
hci_register_dev+0x153/0xa40 net/bluetooth/hci_core.c:2620
__vhci_create_device drivers/bluetooth/hci_vhci.c:434 [inline]
vhci_create_device+0x3ba/0x720 drivers/bluetooth/hci_vhci.c:475
vhci_get_user drivers/bluetooth/hci_vhci.c:532 [inline]
vhci_write+0x3c7/0x480 drivers/bluetooth/hci_vhci.c:612
call_write_iter include/linux/fs.h:1956 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x782/0xaf0 fs/read_write.c:584
ksys_write+0x1a0/0x2c0 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff88801e5458c0
which belongs to the cache kmalloc-8 of size 8
The buggy address is located 2 bytes to the right of
allocated 5-byte region [ffff88801e5458c0, ffff88801e5458c5)

The buggy address belongs to the physical page:
page:ffffea0000795140 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1e545
flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000800 ffff888012841280 ffffea00004db540 dead000000000002
raw: 0000000000000000 0000000000660066 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 0x12c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY), pid 25, tgid 25 (kdevtmpfs), ts 9275165846, free_ts 9274763750
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1536
prep_new_page mm/page_alloc.c:1543 [inline]
get_page_from_freelist+0x31db/0x3360 mm/page_alloc.c:3170
__alloc_pages+0x255/0x670 mm/page_alloc.c:4426
alloc_slab_page+0x6a/0x160 mm/slub.c:1870
allocate_slab mm/slub.c:2017 [inline]
new_slab+0x84/0x2f0 mm/slub.c:2070
___slab_alloc+0xc85/0x1310 mm/slub.c:3223
__slab_alloc mm/slub.c:3322 [inline]
__slab_alloc_node mm/slub.c:3375 [inline]
slab_alloc_node mm/slub.c:3468 [inline]
__kmem_cache_alloc_node+0x1af/0x270 mm/slub.c:3517
__do_kmalloc_node mm/slab_common.c:1022 [inline]
__kmalloc_node_track_caller+0xa5/0x230 mm/slab_common.c:1043
kstrdup+0x3a/0x70 mm/util.c:62
smack_inode_init_security+0x5ed/0x740 security/smack/smack_lsm.c:1046
security_inode_init_security+0x1a1/0x470 security/security.c:1648
shmem_mknod+0xc6/0x1d0 mm/shmem.c:3221
vfs_mknod+0x308/0x350 fs/namei.c:3998
handle_create drivers/base/devtmpfs.c:219 [inline]
handle drivers/base/devtmpfs.c:384 [inline]
devtmpfs_work_loop+0x95c/0x1030 drivers/base/devtmpfs.c:399
devtmpfsd+0x48/0x50 drivers/base/devtmpfs.c:441
kthread+0x2d3/0x370 kernel/kthread.c:388
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+0x8c3/0x9f0 mm/page_alloc.c:2312
free_unref_page+0x37/0x3f0 mm/page_alloc.c:2405
mm_free_pgd kernel/fork.c:803 [inline]
__mmdrop+0xb8/0x3d0 kernel/fork.c:919
free_bprm+0x144/0x330 fs/exec.c:1492
kernel_execve+0x8f5/0xa10 fs/exec.c:2026
call_usermodehelper_exec_async+0x233/0x370 kernel/umh.c:110
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

Memory state around the buggy address:
ffff88801e545780: 05 fc fc fc fc 05 fc fc fc fc 05 fc fc fc fc 05
ffff88801e545800: fc fc fc fc 05 fc fc fc fc 00 fc fc fc fc 00 fc
>ffff88801e545880: fc fc fc 00 fc fc fc fc 05 fc fc fc fc 00 fc fc
^
ffff88801e545900: fc fc 00 fc fc fc fc 00 fc fc fc fc 05 fc fc fc
ffff88801e545980: fc 05 fc fc fc fc fa fc fc fc fc 00 fc fc fc fc
==================================================================


---
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 syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection

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

[shaozhengchao]

The size of the member name in struct hci_mon_new_index is fixed at 8
bytes. The size of the member name in struct hci_dev is not fixed. When
the size of the member name in struct hci_dev is less than 8 bytes,
out-of-bounds read will occur.

It seems that the member name in struct hci_mon_new_index is no longer
used and can be removed directly.

Zhengchao Shao

[Edward AD]

please test slab oob in create_monitor_event

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git f291209eca5e

diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c
index 5e4f718073b7..b3529051d886 100644
--- a/net/bluetooth/hci_sock.c
+++ b/net/bluetooth/hci_sock.c
@@ -477,6 +477,7 @@ static struct sk_buff *create_monitor_event(struct hci_dev *hdev, int event)
struct hci_mon_index_info *ii;
struct sk_buff *skb;
__le16 opcode;
+ size_t sn, hn;

switch (event) {
case HCI_DEV_REG:
@@ -488,7 +489,10 @@ static struct sk_buff *create_monitor_event(struct hci_dev *hdev, int event)
ni->type = hdev->dev_type;
ni->bus = hdev->bus;
bacpy(&ni->bdaddr, &hdev->bdaddr);
- memcpy(ni->name, hdev->name, 8);
+ sn = sizeof(ni->name);
+ hn = sizeof(hdev->name);
+ sn = sn > hn ? hn : sn;
+ memcpy(ni->name, hdev->name, sn);

opcode = cpu_to_le16(HCI_MON_NEW_INDEX);
break;

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-out-of-bounds Read in create_monitor_event

==================================================================
BUG: KASAN: slab-out-of-bounds in create_monitor_event+0x88d/0x930 net/bluetooth/hci_sock.c:495
Read of size 8 at addr ffff888016f7dbe7 by task syz-executor.0/5455

CPU: 1 PID: 5455 Comm: syz-executor.0 Not tainted 6.6.0-rc4-syzkaller-00158-gf291209eca5e-dirty #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0x163/0x540 mm/kasan/report.c:475
kasan_report+0x175/0x1b0 mm/kasan/report.c:588

create_monitor_event+0x88d/0x930 net/bluetooth/hci_sock.c:495
send_monitor_replay+0x7a/0x5d0 net/bluetooth/hci_sock.c:727
hci_sock_bind+0x85c/0x1140 net/bluetooth/hci_sock.c:1391

__sys_bind+0x23a/0x2e0 net/socket.c:1849
__do_sys_bind net/socket.c:1860 [inline]
__se_sys_bind net/socket.c:1858 [inline]
__x64_sys_bind+0x7a/0x90 net/socket.c:1858
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

RIP: 0033:0x7ff10207cae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff102e640c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000031
RAX: ffffffffffffffda RBX: 00007ff10219bf80 RCX: 00007ff10207cae9

RDX: 0000000000000006 RSI: 0000000020000000 RDI: 0000000000000004

RBP: 00007ff1020c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007ff10219bf80 R15: 00007ffeb9dbb4d8
</TASK>

Allocated by task 5392:

kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:374 [inline]
__kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:383
kasan_kmalloc include/linux/kasan.h:198 [inline]
__do_kmalloc_node mm/slab_common.c:1023 [inline]
__kmalloc_node_track_caller+0xb6/0x230 mm/slab_common.c:1043
kvasprintf+0xdf/0x190 lib/kasprintf.c:25
kobject_set_name_vargs+0x61/0x120 lib/kobject.c:272
dev_set_name+0xd5/0x120 drivers/base/core.c:3427
hci_register_dev+0x153/0xa40 net/bluetooth/hci_core.c:2620
__vhci_create_device drivers/bluetooth/hci_vhci.c:434 [inline]
vhci_create_device+0x3ba/0x720 drivers/bluetooth/hci_vhci.c:475
vhci_get_user drivers/bluetooth/hci_vhci.c:532 [inline]
vhci_write+0x3c7/0x480 drivers/bluetooth/hci_vhci.c:612
call_write_iter include/linux/fs.h:1956 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x782/0xaf0 fs/read_write.c:584
ksys_write+0x1a0/0x2c0 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff888016f7dbe0

which belongs to the cache kmalloc-8 of size 8
The buggy address is located 2 bytes to the right of

allocated 5-byte region [ffff888016f7dbe0, ffff888016f7dbe5)

The buggy address belongs to the physical page:

page:ffffea00005bdf40 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16f7d

flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()

raw: 00fff00000000800 ffff888012841280 ffffea0000753bc0 dead000000000002

raw: 0000000000000000 0000000000660066 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 1, tgid 1 (swapper/0), ts 8220705871, free_ts 8218626819

set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1536
prep_new_page mm/page_alloc.c:1543 [inline]
get_page_from_freelist+0x31db/0x3360 mm/page_alloc.c:3170
__alloc_pages+0x255/0x670 mm/page_alloc.c:4426

alloc_page_interleave+0x22/0x1d0 mm/mempolicy.c:2130

alloc_slab_page+0x6a/0x160 mm/slub.c:1870
allocate_slab mm/slub.c:2017 [inline]
new_slab+0x84/0x2f0 mm/slub.c:2070
___slab_alloc+0xc85/0x1310 mm/slub.c:3223
__slab_alloc mm/slub.c:3322 [inline]
__slab_alloc_node mm/slub.c:3375 [inline]
slab_alloc_node mm/slub.c:3468 [inline]
__kmem_cache_alloc_node+0x1af/0x270 mm/slub.c:3517
__do_kmalloc_node mm/slab_common.c:1022 [inline]
__kmalloc_node_track_caller+0xa5/0x230 mm/slab_common.c:1043
kstrdup+0x3a/0x70 mm/util.c:62

__kernfs_new_node+0x9d/0x870 fs/kernfs/dir.c:611
kernfs_new_node fs/kernfs/dir.c:679 [inline]
kernfs_create_dir_ns+0x94/0x230 fs/kernfs/dir.c:1040
sysfs_create_dir_ns+0x189/0x390 fs/sysfs/dir.c:59
create_dir lib/kobject.c:73 [inline]
kobject_add_internal+0x61d/0xc30 lib/kobject.c:238
kobject_add_varg lib/kobject.c:372 [inline]
kobject_add+0x152/0x210 lib/kobject.c:424
device_add+0x4b5/0xd30 drivers/base/core.c:3562

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+0x8c3/0x9f0 mm/page_alloc.c:2312

free_unref_page_list+0x596/0x830 mm/page_alloc.c:2451
release_pages+0x2113/0x23f0 mm/swap.c:1042
tlb_batch_pages_flush mm/mmu_gather.c:98 [inline]
tlb_flush_mmu_free mm/mmu_gather.c:293 [inline]
tlb_flush_mmu+0x34c/0x4e0 mm/mmu_gather.c:300
tlb_finish_mmu+0xd4/0x1f0 mm/mmu_gather.c:392
exit_mmap+0x4d3/0xc50 mm/mmap.c:3223
__mmput+0x115/0x3c0 kernel/fork.c:1349

free_bprm+0x144/0x330 fs/exec.c:1492
kernel_execve+0x8f5/0xa10 fs/exec.c:2026
call_usermodehelper_exec_async+0x233/0x370 kernel/umh.c:110
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

Memory state around the buggy address:

ffff888016f7da80: fc fc fc fc 05 fc fc fc fc 00 fc fc fc fc 05 fc
ffff888016f7db00: fc fc fc 06 fc fc fc fc 06 fc fc fc fc 06 fc fc
>ffff888016f7db80: fc fc 05 fc fc fc fc 05 fc fc fc fc 05 fc fc fc
^
ffff888016f7dc00: fc 06 fc fc fc fc 06 fc fc fc fc 06 fc fc fc fc
ffff888016f7dc80: 05 fc fc fc fc fa fc fc fc fc fa fc fc fc fc 06
==================================================================


Tested on:

commit: f291209e Merge tag 'net-6.6-rc5' of git://git.kernel.o..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=136919e9680000

kernel config: https://syzkaller.appspot.com/x/.config?x=7a5682d32a74b423
dashboard link: https://syzkaller.appspot.com/bug?extid=c90849c50ed209d77689
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=160802ba680000

[Edward AD]

please test slab oob in create_monitor_event

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git f291209eca5e

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 195aea2198a9..266cf03156d4 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -2621,7 +2621,9 @@ int hci_register_dev(struct hci_dev *hdev)
if (error)
return error;

+ printk("%p, %d, %s\n", hdev->name, sizeof(hdev->name), __func__);
hdev->name = dev_name(&hdev->dev);
+ printk("%p, %d, %s, %s\n", hdev->name, sizeof(hdev->name), hdev->name, __func__);
hdev->id = id;

BT_DBG("%p name %s bus %d", hdev, hdev->name, hdev->bus);
diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c
index 5e4f718073b7..50658e303655 100644

--- a/net/bluetooth/hci_sock.c
+++ b/net/bluetooth/hci_sock.c
@@ -477,6 +477,7 @@ static struct sk_buff *create_monitor_event(struct hci_dev *hdev, int event)
struct hci_mon_index_info *ii;
struct sk_buff *skb;
__le16 opcode;
+ size_t sn, hn;

switch (event) {
case HCI_DEV_REG:

@@ -488,7 +489,11 @@ static struct sk_buff *create_monitor_event(struct hci_dev *hdev, int event)

ni->type = hdev->dev_type;
ni->bus = hdev->bus;
bacpy(&ni->bdaddr, &hdev->bdaddr);
- memcpy(ni->name, hdev->name, 8);
+ sn = sizeof(ni->name);
+ hn = sizeof(hdev->name);

+ printk("%d, %d, %s, %p\n", sn, hn, __func__, hdev->name);

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-out-of-bounds Read in create_monitor_event

8, 8, create_monitor_event, ffff888016b70be0
==================================================================
BUG: KASAN: slab-out-of-bounds in create_monitor_event+0x976/0x9c0 net/bluetooth/hci_sock.c:496
Read of size 8 at addr ffff888016b70be7 by task syz-executor.0/5457

CPU: 0 PID: 5457 Comm: syz-executor.0 Not tainted 6.6.0-rc4-syzkaller-00158-gf291209eca5e-dirty #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0x163/0x540 mm/kasan/report.c:475
kasan_report+0x175/0x1b0 mm/kasan/report.c:588

create_monitor_event+0x976/0x9c0 net/bluetooth/hci_sock.c:496
send_monitor_replay+0x7a/0x5d0 net/bluetooth/hci_sock.c:728
hci_sock_bind+0x85c/0x1140 net/bluetooth/hci_sock.c:1392

__sys_bind+0x23a/0x2e0 net/socket.c:1849
__do_sys_bind net/socket.c:1860 [inline]
__se_sys_bind net/socket.c:1858 [inline]
__x64_sys_bind+0x7a/0x90 net/socket.c:1858
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

RIP: 0033:0x7f3616e7cae9

Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48

RSP: 002b:00007f3617b2a0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000031
RAX: ffffffffffffffda RBX: 00007f3616f9bf80 RCX: 00007f3616e7cae9

RDX: 0000000000000006 RSI: 0000000020000000 RDI: 0000000000000004

RBP: 00007f3616ec847a R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 000000000000000b R14: 00007f3616f9bf80 R15: 00007ffd3cce9288
</TASK>

Allocated by task 5393:

kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:374 [inline]
__kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:383
kasan_kmalloc include/linux/kasan.h:198 [inline]
__do_kmalloc_node mm/slab_common.c:1023 [inline]
__kmalloc_node_track_caller+0xb6/0x230 mm/slab_common.c:1043
kvasprintf+0xdf/0x190 lib/kasprintf.c:25
kobject_set_name_vargs+0x61/0x120 lib/kobject.c:272
dev_set_name+0xd5/0x120 drivers/base/core.c:3427

hci_register_dev+0x154/0xaf0 net/bluetooth/hci_core.c:2620

__vhci_create_device drivers/bluetooth/hci_vhci.c:434 [inline]
vhci_create_device+0x3ba/0x720 drivers/bluetooth/hci_vhci.c:475
vhci_get_user drivers/bluetooth/hci_vhci.c:532 [inline]
vhci_write+0x3c7/0x480 drivers/bluetooth/hci_vhci.c:612
call_write_iter include/linux/fs.h:1956 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x782/0xaf0 fs/read_write.c:584
ksys_write+0x1a0/0x2c0 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff888016b70be0

which belongs to the cache kmalloc-8 of size 8
The buggy address is located 2 bytes to the right of

allocated 5-byte region [ffff888016b70be0, ffff888016b70be5)

The buggy address belongs to the physical page:

page:ffffea00005adc00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16b70

flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()

raw: 00fff00000000800 ffff888012841280 ffffea000050a580 dead000000000002

raw: 0000000000000000 0000000000660066 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 1, tgid 1 (swapper/0), ts 8209251422, free_ts 8189848851

free_unref_page+0x37/0x3f0 mm/page_alloc.c:2405
vfree+0x186/0x2e0 mm/vmalloc.c:2842
delayed_vfree_work+0x56/0x80 mm/vmalloc.c:2763
process_one_work kernel/workqueue.c:2630 [inline]
process_scheduled_works+0x90f/0x1400 kernel/workqueue.c:2703
worker_thread+0xa5f/0xff0 kernel/workqueue.c:2784
kthread+0x2d3/0x370 kernel/kthread.c:388

ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

Memory state around the buggy address:

ffff888016b70a80: fc fc fc fc 04 fc fc fc fc 00 fc fc fc fc 05 fc
ffff888016b70b00: fc fc fc 06 fc fc fc fc 06 fc fc fc fc 06 fc fc
>ffff888016b70b80: fc fc 04 fc fc fc fc 05 fc fc fc fc 05 fc fc fc
^
ffff888016b70c00: fc 06 fc fc fc fc 06 fc fc fc fc 06 fc fc fc fc
ffff888016b70c80: 04 fc fc fc fc fa fc fc fc fc fa fc fc fc fc 06

==================================================================


Tested on:

commit: f291209e Merge tag 'net-6.6-rc5' of git://git.kernel.o..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

console output: https://syzkaller.appspot.com/x/log.txt?x=16ec5316680000

kernel config: https://syzkaller.appspot.com/x/.config?x=7a5682d32a74b423
dashboard link: https://syzkaller.appspot.com/bug?extid=c90849c50ed209d77689
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=1021522e680000

[Edward AD]

+ sn = strlen(ni->name);
+ hn = strlen(hdev->name);

+ printk("%d, %d, %s, %p\n", sn, hn, __func__, hdev->name);
+ sn = sn > hn ? hn : sn;

+ memcpy(ni->name, hdev->name, hn);

opcode = cpu_to_le16(HCI_MON_NEW_INDEX);
break;

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+c90849...@syzkaller.appspotmail.com

Tested on:

commit: f291209e Merge tag 'net-6.6-rc5' of git://git.kernel.o..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

console output: https://syzkaller.appspot.com/x/log.txt?x=1302c3ee680000

kernel config: https://syzkaller.appspot.com/x/.config?x=7a5682d32a74b423
dashboard link: https://syzkaller.appspot.com/bug?extid=c90849c50ed209d77689
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=12a2e111680000

Note: testing is done by a robot and is best-effort only.

[Edward AD]

When accessing hdev->name, the actual string length should prevail

Reported-by: syzbot+c90849...@syzkaller.appspotmail.com
Fixes: dcda165706b9 ("Bluetooth: hci_core: Fix build warnings")

Signed-off-by: Edward AD <twuu...@gmail.com>
---
net/bluetooth/hci_sock.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c
index 5e4f718073b7..72abe54c45dd 100644
--- a/net/bluetooth/hci_sock.c
+++ b/net/bluetooth/hci_sock.c
@@ -488,7 +488,7 @@ static struct sk_buff *create_monitor_event(struct hci_dev *hdev, int event)

ni->type = hdev->dev_type;
ni->bus = hdev->bus;
bacpy(&ni->bdaddr, &hdev->bdaddr);
- memcpy(ni->name, hdev->name, 8);

+ memcpy(ni->name, hdev->name, strlen(hdev->name));

opcode = cpu_to_le16(HCI_MON_NEW_INDEX);
break;
--
2.25.1

[patchwork-b...@kernel.org]

Hello:

This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <luiz.vo...@intel.com>:

On Tue, 10 Oct 2023 13:36:57 +0800 you wrote:
> When accessing hdev->name, the actual string length should prevail
>
> Reported-by: syzbot+c90849...@syzkaller.appspotmail.com
> Fixes: dcda165706b9 ("Bluetooth: hci_core: Fix build warnings")
> Signed-off-by: Edward AD <twuu...@gmail.com>
> ---
> net/bluetooth/hci_sock.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

Here is the summary with links:
- Bluetooth: hci_sock: fix slab oob read in create_monitor_event
https://git.kernel.org/bluetooth/bluetooth-next/c/78480de55a96

You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

[Kees Cook]

Uh, what's going on here?

hdev is:

struct hci_dev {
...
const char *name;

ni is:

struct hci_mon_new_index {
char name[8];

You can't use "strlen" here in the case that "hdev->name" is larger than
8 bytes.

Also, why memcpy() and not strscpy()? Is this supposed to be padded out
with %NUL bytes? It appears to be sent over the network, so "yes" seems
to be the safe answer.

Should ni->name be always %NUL terminated? That I can't tell for sure,
but I assume "no", because the solution was to explicitly copy all the
bytes _except_ the %NUL byte (using strlen).

struct hci_mon_new_index's "name" should be marked __nonstring, and
instead strtomem_pad() should be used instead of memcpy.

-Kees

>
> opcode = cpu_to_le16(HCI_MON_NEW_INDEX);
> break;
> --
> 2.25.1
>

--
Kees Cook