If we send a command and the command is timeout, the hci_cmd_timeout()
will run. Then we use hci_sock_ioctl() to inquiry the command, it will
deallocate the req_skb. But the req_skb could be dereferenced in the
hci_cmd_timeout(). As a result, the use-after-free bug will happen.
The detail is shown below:
thread 1 thread2
hci_sock_ioctl() | hci_sock_sendmsg()
hci_inquiry() | queue_work(...,&hdev->cmd_work)
hci_req_sync() | hci_cmd_work()
__hci_req_sync() | queue_delayed_work(...,&hdev->cmd_timer)
kfree_skb(hdev->req_skb) | hci_cmd_timeout()
| hci_skb_opcode(hdev->req_skb)
The KASan report for such a POC is shown below:
==================================================================
BUG: KASAN: slab-use-after-free in hci_cmd_timeout+0x3c/0x110
Read of size 2 at addr ffff8880087a1c78 by task kworker/u21:0/131
...
Workqueue: hci0 hci_cmd_timeout
Call Trace:
<TASK>
dump_stack_lvl+0x84/0xc0
print_address_description+0x78/0x440
print_report+0x11b/0x220
? pfn_valid+0xe4/0x140
? __virt_addr_valid+0x7c/0x90
? hci_cmd_timeout+0x3c/0x110
kasan_report+0xc7/0x100
? hci_cmd_timeout+0x3c/0x110
hci_cmd_timeout+0x3c/0x110
process_one_work+0x2df/0x610
worker_thread+0x72f/0x870
? pr_cont_work+0x280/0x280
kthread+0x18a/0x1b0
? kthread_blkcg+0x50/0x50
ret_from_fork+0x34/0x50
? kthread_blkcg+0x50/0x50
ret_from_fork_asm+0x11/0x20
</TASK>
Allocated by task 131 on cpu 1 at 45.611537s:
kasan_save_track+0x32/0x90
__kasan_slab_alloc+0x4b/0x60
kmem_cache_alloc+0xcb/0x240
skb_clone+0x117/0x170
hci_cmd_work+0x19c/0x2a0
process_one_work+0x2df/0x610
worker_thread+0x72f/0x870
kthread+0x18a/0x1b0
ret_from_fork+0x34/0x50
ret_from_fork_asm+0x11/0x20
Freed by task 135 on cpu 2 at 47.671850s:
kasan_save_track+0x32/0x90
kasan_save_free_info+0x40/0x50
poison_slab_object+0x118/0x180
__kasan_slab_free+0x12/0x30
kmem_cache_free+0x92/0x200
__hci_req_sync+0x2e2/0x350
hci_req_sync+0x73/0x90
hci_inquiry+0x1c1/0x350
sock_do_ioctl+0x50/0x1a0
sock_ioctl+0x2ea/0x3b0
__se_sys_ioctl+0x89/0xd0
do_syscall_64+0xc4/0x1b0
entry_SYSCALL_64_after_hwframe+0x62/0x6a
...
In order to mitigate the bug, add cancel_delayed_work_sync() in
__hci_req_sync() to cancel the cmd_timer before the req_skb is
deallocated.
Fixes: 9afee94939e3 ("Bluetooth: Fix memory leak at end of hci requests")
Signed-off-by: Duoming Zhou <[email protected]>
---
net/bluetooth/hci_request.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/net/bluetooth/hci_request.c b/net/bluetooth/hci_request.c
index 00e02138003..06692c71093 100644
--- a/net/bluetooth/hci_request.c
+++ b/net/bluetooth/hci_request.c
@@ -179,6 +179,7 @@ int __hci_req_sync(struct hci_dev *hdev, int (*func)(struct hci_request *req,
break;
}
+ cancel_delayed_work_sync(&hdev->cmd_timer);
kfree_skb(hdev->req_skb);
hdev->req_skb = NULL;
hdev->req_status = hdev->req_result = 0;
--
2.17.1
This is automated email and please do not reply to this email!
Dear submitter,
Thank you for submitting the patches to the linux bluetooth mailing list.
This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=842493
---Test result---
Test Summary:
CheckPatch PASS 0.62 seconds
GitLint PASS 0.28 seconds
SubjectPrefix PASS 0.11 seconds
BuildKernel PASS 30.02 seconds
CheckAllWarning PASS 32.99 seconds
CheckSparse PASS 39.79 seconds
CheckSmatch FAIL 36.07 seconds
BuildKernel32 PASS 28.87 seconds
TestRunnerSetup PASS 520.44 seconds
TestRunner_l2cap-tester PASS 18.34 seconds
TestRunner_iso-tester FAIL 34.77 seconds
TestRunner_bnep-tester PASS 4.69 seconds
TestRunner_mgmt-tester PASS 108.22 seconds
TestRunner_rfcomm-tester PASS 7.19 seconds
TestRunner_sco-tester PASS 14.90 seconds
TestRunner_ioctl-tester PASS 7.54 seconds
TestRunner_mesh-tester PASS 5.69 seconds
TestRunner_smp-tester PASS 6.66 seconds
TestRunner_userchan-tester PASS 4.85 seconds
IncrementalBuild PASS 27.65 seconds
Details
##############################
Test: CheckSmatch - FAIL
Desc: Run smatch tool with source
Output:
Segmentation fault (core dumped)
make[4]: *** [scripts/Makefile.build:244: net/bluetooth/hci_core.o] Error 139
make[4]: *** Deleting file 'net/bluetooth/hci_core.o'
make[3]: *** [scripts/Makefile.build:485: net/bluetooth] Error 2
make[2]: *** [scripts/Makefile.build:485: net] Error 2
make[2]: *** Waiting for unfinished jobs....
Segmentation fault (core dumped)
make[4]: *** [scripts/Makefile.build:244: drivers/bluetooth/bcm203x.o] Error 139
make[4]: *** Deleting file 'drivers/bluetooth/bcm203x.o'
make[4]: *** Waiting for unfinished jobs....
Segmentation fault (core dumped)
make[4]: *** [scripts/Makefile.build:244: drivers/bluetooth/bpa10x.o] Error 139
make[4]: *** Deleting file 'drivers/bluetooth/bpa10x.o'
make[3]: *** [scripts/Makefile.build:485: drivers/bluetooth] Error 2
make[2]: *** [scripts/Makefile.build:485: drivers] Error 2
make[1]: *** [/github/workspace/src/src/Makefile:1919: .] Error 2
make: *** [Makefile:240: __sub-make] Error 2
##############################
Test: TestRunner_iso-tester - FAIL
Desc: Run iso-tester with test-runner
Output:
Total: 121, Passed: 120 (99.2%), Failed: 1, Not Run: 0
Failed Test Cases
ISO Connect Suspend - Success Failed 4.180 seconds
---
Regards,
Linux Bluetooth