There is a race condition between l2cap_chan_timeout() and
l2cap_chan_del(). When we use l2cap_chan_del() to delete the
channel, the chan->conn will be set to null. But the conn could
be dereferenced again in the mutex_lock() of l2cap_chan_timeout().
As a result the null pointer dereference bug will happen. The
KASAN report triggered by POC is shown below:
[ 472.074580] ==================================================================
[ 472.075284] BUG: KASAN: null-ptr-deref in mutex_lock+0x68/0xc0
[ 472.075308] Write of size 8 at addr 0000000000000158 by task kworker/0:0/7
[ 472.075308]
[ 472.075308] CPU: 0 PID: 7 Comm: kworker/0:0 Not tainted 6.9.0-rc5-00356-g78c0094a146b #36
[ 472.075308] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu4
[ 472.075308] Workqueue: events l2cap_chan_timeout
[ 472.075308] Call Trace:
[ 472.075308] <TASK>
[ 472.075308] dump_stack_lvl+0x137/0x1a0
[ 472.075308] print_report+0x101/0x250
[ 472.075308] ? __virt_addr_valid+0x77/0x160
[ 472.075308] ? mutex_lock+0x68/0xc0
[ 472.075308] kasan_report+0x139/0x170
[ 472.075308] ? mutex_lock+0x68/0xc0
[ 472.075308] kasan_check_range+0x2c3/0x2e0
[ 472.075308] mutex_lock+0x68/0xc0
[ 472.075308] l2cap_chan_timeout+0x181/0x300
[ 472.075308] process_one_work+0x5d2/0xe00
[ 472.075308] worker_thread+0xe1d/0x1660
[ 472.075308] ? pr_cont_work+0x5e0/0x5e0
[ 472.075308] kthread+0x2b7/0x350
[ 472.075308] ? pr_cont_work+0x5e0/0x5e0
[ 472.075308] ? kthread_blkcg+0xd0/0xd0
[ 472.075308] ret_from_fork+0x4d/0x80
[ 472.075308] ? kthread_blkcg+0xd0/0xd0
[ 472.075308] ret_from_fork_asm+0x11/0x20
[ 472.075308] </TASK>
[ 472.075308] ==================================================================
[ 472.094860] Disabling lock debugging due to kernel taint
[ 472.096136] BUG: kernel NULL pointer dereference, address: 0000000000000158
[ 472.096136] #PF: supervisor write access in kernel mode
[ 472.096136] #PF: error_code(0x0002) - not-present page
[ 472.096136] PGD 0 P4D 0
[ 472.096136] Oops: 0002 [#1] PREEMPT SMP KASAN NOPTI
[ 472.096136] CPU: 0 PID: 7 Comm: kworker/0:0 Tainted: G B 6.9.0-rc5-00356-g78c0094a146b #36
[ 472.096136] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu4
[ 472.096136] Workqueue: events l2cap_chan_timeout
[ 472.096136] RIP: 0010:mutex_lock+0x88/0xc0
[ 472.096136] Code: be 08 00 00 00 e8 f8 23 1f fd 4c 89 f7 be 08 00 00 00 e8 eb 23 1f fd 42 80 3c 23 00 74 08 48 88
[ 472.096136] RSP: 0018:ffff88800744fc78 EFLAGS: 00000246
[ 472.096136] RAX: 0000000000000000 RBX: 1ffff11000e89f8f RCX: ffffffff8457c865
[ 472.096136] RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffff88800744fc78
[ 472.096136] RBP: 0000000000000158 R08: ffff88800744fc7f R09: 1ffff11000e89f8f
[ 472.096136] R10: dffffc0000000000 R11: ffffed1000e89f90 R12: dffffc0000000000
[ 472.096136] R13: 0000000000000158 R14: ffff88800744fc78 R15: ffff888007405a00
[ 472.096136] FS: 0000000000000000(0000) GS:ffff88806d200000(0000) knlGS:0000000000000000
[ 472.096136] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 472.096136] CR2: 0000000000000158 CR3: 000000000da32000 CR4: 00000000000006f0
[ 472.096136] Call Trace:
[ 472.096136] <TASK>
[ 472.096136] ? __die_body+0x8d/0xe0
[ 472.096136] ? page_fault_oops+0x6b8/0x9a0
[ 472.096136] ? kernelmode_fixup_or_oops+0x20c/0x2a0
[ 472.096136] ? do_user_addr_fault+0x1027/0x1340
[ 472.096136] ? _printk+0x7a/0xa0
[ 472.096136] ? mutex_lock+0x68/0xc0
[ 472.096136] ? add_taint+0x42/0xd0
[ 472.096136] ? exc_page_fault+0x6a/0x1b0
[ 472.096136] ? asm_exc_page_fault+0x26/0x30
[ 472.096136] ? mutex_lock+0x75/0xc0
[ 472.096136] ? mutex_lock+0x88/0xc0
[ 472.096136] ? mutex_lock+0x75/0xc0
[ 472.096136] l2cap_chan_timeout+0x181/0x300
[ 472.096136] process_one_work+0x5d2/0xe00
[ 472.096136] worker_thread+0xe1d/0x1660
[ 472.096136] ? pr_cont_work+0x5e0/0x5e0
[ 472.096136] kthread+0x2b7/0x350
[ 472.096136] ? pr_cont_work+0x5e0/0x5e0
[ 472.096136] ? kthread_blkcg+0xd0/0xd0
[ 472.096136] ret_from_fork+0x4d/0x80
[ 472.096136] ? kthread_blkcg+0xd0/0xd0
[ 472.096136] ret_from_fork_asm+0x11/0x20
[ 472.096136] </TASK>
[ 472.096136] Modules linked in:
[ 472.096136] CR2: 0000000000000158
[ 472.096136] ---[ end trace 0000000000000000 ]---
[ 472.096136] RIP: 0010:mutex_lock+0x88/0xc0
[ 472.096136] Code: be 08 00 00 00 e8 f8 23 1f fd 4c 89 f7 be 08 00 00 00 e8 eb 23 1f fd 42 80 3c 23 00 74 08 48 88
[ 472.096136] RSP: 0018:ffff88800744fc78 EFLAGS: 00000246
[ 472.096136] RAX: 0000000000000000 RBX: 1ffff11000e89f8f RCX: ffffffff8457c865
[ 472.096136] RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffff88800744fc78
[ 472.096136] RBP: 0000000000000158 R08: ffff88800744fc7f R09: 1ffff11000e89f8f
[ 472.132932] R10: dffffc0000000000 R11: ffffed1000e89f90 R12: dffffc0000000000
[ 472.132932] R13: 0000000000000158 R14: ffff88800744fc78 R15: ffff888007405a00
[ 472.132932] FS: 0000000000000000(0000) GS:ffff88806d200000(0000) knlGS:0000000000000000
[ 472.132932] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 472.132932] CR2: 0000000000000158 CR3: 000000000da32000 CR4: 00000000000006f0
[ 472.132932] Kernel panic - not syncing: Fatal exception
[ 472.132932] Kernel Offset: disabled
[ 472.132932] ---[ end Kernel panic - not syncing: Fatal exception ]---
Add a check to judge whether the conn is null in l2cap_chan_timeout()
in order to mitigate the bug.
Fixes: 3df91ea20e74 ("Bluetooth: Revert to mutexes from RCU list")
Signed-off-by: Duoming Zhou <[email protected]>
---
net/bluetooth/l2cap_core.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 84fc70862d7..5761d37c553 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -415,6 +415,9 @@ static void l2cap_chan_timeout(struct work_struct *work)
BT_DBG("chan %p state %s", chan, state_to_string(chan->state));
+ if (!conn)
+ return;
+
mutex_lock(&conn->chan_lock);
/* __set_chan_timer() calls l2cap_chan_hold(chan) while scheduling
* this work. No need to call l2cap_chan_hold(chan) here again.
--
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=849889
---Test result---
Test Summary:
CheckPatch PASS 0.67 seconds
GitLint FAIL 0.58 seconds
SubjectPrefix PASS 0.12 seconds
BuildKernel PASS 31.05 seconds
CheckAllWarning PASS 32.65 seconds
CheckSparse PASS 38.12 seconds
CheckSmatch FAIL 36.16 seconds
BuildKernel32 PASS 28.92 seconds
TestRunnerSetup PASS 520.21 seconds
TestRunner_l2cap-tester PASS 19.94 seconds
TestRunner_iso-tester FAIL 33.24 seconds
TestRunner_bnep-tester PASS 4.73 seconds
TestRunner_mgmt-tester PASS 111.97 seconds
TestRunner_rfcomm-tester PASS 7.27 seconds
TestRunner_sco-tester PASS 15.24 seconds
TestRunner_ioctl-tester PASS 7.77 seconds
TestRunner_mesh-tester PASS 5.79 seconds
TestRunner_smp-tester PASS 6.74 seconds
TestRunner_userchan-tester PASS 4.96 seconds
IncrementalBuild PASS 28.10 seconds
Details
##############################
Test: GitLint - FAIL
Desc: Run gitlint
Output:
Bluetooth: l2cap: fix null-ptr-deref in l2cap_chan_timeout
WARNING: I3 - ignore-body-lines: gitlint will be switching from using Python regex 'match' (match beginning) to 'search' (match anywhere) semantics. Please review your ignore-body-lines.regex option accordingly. To remove this warning, set general.regex-style-search=True. More details: https://jorisroovers.github.io/gitlint/configuration/#regex-style-search
10: B1 Line exceeds max length (81>80): "[ 472.074580] =================================================================="
14: B1 Line exceeds max length (92>80): "[ 472.075308] CPU: 0 PID: 7 Comm: kworker/0:0 Not tainted 6.9.0-rc5-00356-g78c0094a146b #36"
15: B1 Line exceeds max length (116>80): "[ 472.075308] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu4"
38: B1 Line exceeds max length (81>80): "[ 472.075308] =================================================================="
45: B1 Line exceeds max length (109>80): "[ 472.096136] CPU: 0 PID: 7 Comm: kworker/0:0 Tainted: G B 6.9.0-rc5-00356-g78c0094a146b #36"
46: B1 Line exceeds max length (116>80): "[ 472.096136] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu4"
49: B1 Line exceeds max length (116>80): "[ 472.096136] Code: be 08 00 00 00 e8 f8 23 1f fd 4c 89 f7 be 08 00 00 00 e8 eb 23 1f fd 42 80 3c 23 00 74 08 48 88"
56: B1 Line exceeds max length (91>80): "[ 472.096136] FS: 0000000000000000(0000) GS:ffff88806d200000(0000) knlGS:0000000000000000"
88: B1 Line exceeds max length (116>80): "[ 472.096136] Code: be 08 00 00 00 e8 f8 23 1f fd 4c 89 f7 be 08 00 00 00 e8 eb 23 1f fd 42 80 3c 23 00 74 08 48 88"
95: B1 Line exceeds max length (91>80): "[ 472.132932] FS: 0000000000000000(0000) GS:ffff88806d200000(0000) knlGS:0000000000000000"
##############################
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: 122, Passed: 121 (99.2%), Failed: 1, Not Run: 0
Failed Test Cases
ISO Connect Suspend - Success Failed 4.176 seconds
---
Regards,
Linux Bluetooth
Hello:
This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <[email protected]>:
On Thu, 2 May 2024 20:57:36 +0800 you wrote:
> There is a race condition between l2cap_chan_timeout() and
> l2cap_chan_del(). When we use l2cap_chan_del() to delete the
> channel, the chan->conn will be set to null. But the conn could
> be dereferenced again in the mutex_lock() of l2cap_chan_timeout().
> As a result the null pointer dereference bug will happen. The
> KASAN report triggered by POC is shown below:
>
> [...]
Here is the summary with links:
- Bluetooth: l2cap: fix null-ptr-deref in l2cap_chan_timeout
https://git.kernel.org/bluetooth/bluetooth-next/c/8192cea84c6c
You are awesome, thank you!
--
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