On Wed, Mar 3, 2021 at 11:11 AM Gopal Tiwari <gtiwari@xxxxxxxxxx> wrote: > > Hi, > > I tried to search the patch for one of the bugzilla reported (Internal) https://bugzilla.redhat.com/show_bug.cgi?id=1916057 with the traces > > [ 405.938525] Workqueue: hci0 hci_rx_work [bluetooth] > [ 405.941360] RIP: 0010:amp_read_loc_assoc_final_data+0xfc/0x1c0 [bluetooth] > [ 405.944740] Code: 89 44 24 29 48 b8 00 00 00 00 00 fc ff df 0f b6 04 02 84 c0 74 08 3c 01 0f 8e 9d 00 00 00 0f b7 85 c0 03 00 00 66 89 44 24 2b <f0> 41 80 4c 24 30 04 4c 8d 64 24 68 48 89 ee 4c 89 e7 e8 3d 48 fe > [ 405.952396] RSP: 0018:ffff88802ea0f838 EFLAGS: 00010246 > [ 405.955368] RAX: 0000000000000000 RBX: 1ffff11005d41f08 RCX: dffffc0000000000 > [ 405.958669] RDX: 1ffff110254cc878 RSI: ffff88802eeee000 RDI: ffff88812a6643c0 > [ 405.961980] RBP: ffff88812a664000 R08: 0000000000000000 R09: 0000000000000000 > [ 405.965319] R10: ffff88802ea0fd00 R11: 0000000000000000 R12: 0000000000000000 > [ 405.968624] R13: 0000000000000041 R14: ffff88802b836800 R15: ffff8881250570c0 > [ 405.971989] FS: 0000000000000000(0000) GS:ffff888055a00000(0000) knlGS:0000000000000000 > [ 405.975645] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 405.978755] CR2: 0000000000000030 CR3: 000000002d200000 CR4: 0000000000340ee0 > [ 405.982150] Call Trace: > [ 405.984768] ? amp_read_loc_assoc+0x170/0x170 [bluetooth] > [ 405.987875] ? rcu_read_unlock+0x50/0x50 > [ 405.990663] ? deref_stack_reg+0xf0/0xf0 > [ 405.993403] ? __module_address+0x3f/0x370 > [ 405.996184] ? hci_cmd_work+0x180/0x330 [bluetooth] > [ 405.999170] ? hci_conn_hash_lookup_handle+0x1a1/0x270 [bluetooth] > [ 406.002354] hci_event_packet+0x1476/0x7e00 [bluetooth] > [ 406.005407] ? arch_stack_walk+0x8f/0xf0 > [ 406.008206] ? ret_from_fork+0x27/0x50 > [ 406.010887] ? hci_cmd_complete_evt+0xbf70/0xbf70 [bluetooth] > [ 406.013933] ? stack_trace_save+0x8a/0xb0 > [ 406.016618] ? do_profile_hits.isra.4.cold.9+0x2d/0x2d > [ 406.019483] ? lock_acquire+0x1a3/0x970 > [ 406.022092] ? __wake_up_common_lock+0xaf/0x130 > > > I didn't found any solution upstream. After the vmcore analysis I found what is wrong. And took reference from the following patch, which seems to be on the similar line > > commit 6dfccd13db2ff2b709ef60a50163925d477549aa > Author: Anmol Karn <anmol.karan123@xxxxxxxxx> > Date: Wed Sep 30 19:48:13 2020 +0530 > > Bluetooth: Fix null pointer dereference in hci_event_packet() > > AMP_MGR is getting derefernced in hci_phy_link_complete_evt(), when called > from hci_event_packet() and there is a possibility, that hcon->amp_mgr may > not be found when accessing after initialization of hcon. > > - net/bluetooth/hci_event.c:4945 > > How we can avoid this scenario. So I made the chages and tested. It worked or avoided the kernel panic. But I really don't know that some one has already posted the patch. I would have love to backport the patch, I was more of looking for the fix. That's where I didn't applied the reported-by tag as I thought it reported internal only. Hi Gopal, I think it's somewhat inherent to the current kernel unstructured processes with bugs being reported on mailing lists, bugzilla, distro-specific trackers. One useful thing, though, is searching Lore, e.g. searching for just the crashing function: https://lore.kernel.org/lkml/?q=amp_read_loc_assoc_final_data gives the report and the patch (if we filter out all entries produced by your patch, which obviously wasn't yet there before you wrote it :)): 12. [Linux-kernel-mentees] [PATCH net] Bluetooth: Fix NULL pointer dereference in amp_read_loc_assoc_final_data() - by Peilin Ye @ 2020-08-08 4:04 UTC [21%] 13. KASAN: null-ptr-deref Write in amp_read_loc_assoc_final_data - by syzbot @ 2020-07-31 17:04 UTC [13%] > Thanks & regards, > Gopal Tiwari > > > > ----- Original Message ----- > From: "Dmitry Vyukov" <dvyukov@xxxxxxxxxx> > To: "Peilin Ye" <yepeilin.cs@xxxxxxxxx> > Cc: "Marcel Holtmann" <marcel@xxxxxxxxxxxx>, "Johan Hedberg" <johan.hedberg@xxxxxxxxx>, "Andrei Emeltchenko" <andrei.emeltchenko@xxxxxxxxx>, "Greg Kroah-Hartman" <gregkh@xxxxxxxxxxxxxxxxxxx>, "David S. Miller" <davem@xxxxxxxxxxxxx>, "Jakub Kicinski" <kuba@xxxxxxxxxx>, linux-kernel-mentees@xxxxxxxxxxxxxxxxxxxxxxxxx, "syzkaller-bugs" <syzkaller-bugs@xxxxxxxxxxxxxxxx>, "linux-bluetooth" <linux-bluetooth@xxxxxxxxxxxxxxx>, "netdev" <netdev@xxxxxxxxxxxxxxx>, "LKML" <linux-kernel@xxxxxxxxxxxxxxx>, gtiwari@xxxxxxxxxx, syzbot+f4fb0eaafdb51c32a153@xxxxxxxxxxxxxxxxxxxxxxxxx > Sent: Wednesday, March 3, 2021 1:51:41 PM > Subject: Re: [Linux-kernel-mentees] [PATCH net] Bluetooth: Fix NULL pointer dereference in amp_read_loc_assoc_final_data() > > On Sat, Aug 8, 2020 at 6:06 AM Peilin Ye <yepeilin.cs@xxxxxxxxx> wrote: > > > > Prevent amp_read_loc_assoc_final_data() from dereferencing `mgr` as NULL. > > > > Reported-and-tested-by: syzbot+f4fb0eaafdb51c32a153@xxxxxxxxxxxxxxxxxxxxxxxxx > > Fixes: 9495b2ee757f ("Bluetooth: AMP: Process Chan Selected event") > > Signed-off-by: Peilin Ye <yepeilin.cs@xxxxxxxxx> > > --- > > net/bluetooth/amp.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/net/bluetooth/amp.c b/net/bluetooth/amp.c > > index 9c711f0dfae3..be2d469d6369 100644 > > --- a/net/bluetooth/amp.c > > +++ b/net/bluetooth/amp.c > > @@ -297,6 +297,9 @@ void amp_read_loc_assoc_final_data(struct hci_dev *hdev, > > struct hci_request req; > > int err; > > > > + if (!mgr) > > + return; > > + > > cp.phy_handle = hcon->handle; > > cp.len_so_far = cpu_to_le16(0); > > cp.max_len = cpu_to_le16(hdev->amp_assoc_size); > > Not sure what happened here, but the merged patch somehow has a > different author and no Reported-by tag: > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e8bd76ede155fd54d8c41d045dda43cd3174d506 > so let's tell syzbot what fixed it manually: > #syz fix: > Bluetooth: Fix null pointer dereference in amp_read_loc_assoc_final_data >
