From 73e216a8a42c0ef3d08071705c946c38fdbe12b0 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Thu, 5 Sep 2013 08:38:10 -0400 Subject: cifs: ensure that srv_mutex is held when dealing with ssocket pointer Oleksii reported that he had seen an oops similar to this: BUG: unable to handle kernel NULL pointer dereference at 0000000000000088 IP: [] sock_sendmsg+0x93/0xd0 PGD 0 Oops: 0000 [#1] PREEMPT SMP Modules linked in: ipt_MASQUERADE xt_REDIRECT xt_tcpudp iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack ip_tables x_tables carl9170 ath usb_storage f2fs nfnetlink_log nfnetlink md4 cifs dns_resolver hid_generic usbhid hid af_packet uvcvideo videobuf2_vmalloc videobuf2_memops videobuf2_core videodev rfcomm btusb bnep bluetooth qmi_wwan qcserial cdc_wdm usb_wwan usbnet usbserial mii snd_hda_codec_hdmi snd_hda_codec_realtek iwldvm mac80211 coretemp intel_powerclamp kvm_intel kvm iwlwifi snd_hda_intel cfg80211 snd_hda_codec xhci_hcd e1000e ehci_pci snd_hwdep sdhci_pci snd_pcm ehci_hcd microcode psmouse sdhci thinkpad_acpi mmc_core i2c_i801 pcspkr usbcore hwmon snd_timer snd_page_alloc snd ptp rfkill pps_core soundcore evdev usb_common vboxnetflt(O) vboxdrv(O)Oops#2 Part8 loop tun binfmt_misc fuse msr acpi_call(O) ipv6 autofs4 CPU: 0 PID: 21612 Comm: kworker/0:1 Tainted: G W O 3.10.1SIGN #28 Hardware name: LENOVO 2306CTO/2306CTO, BIOS G2ET92WW (2.52 ) 02/22/2013 Workqueue: cifsiod cifs_echo_request [cifs] task: ffff8801e1f416f0 ti: ffff880148744000 task.ti: ffff880148744000 RIP: 0010:[] [] sock_sendmsg+0x93/0xd0 RSP: 0000:ffff880148745b00 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff880148745b78 RCX: 0000000000000048 RDX: ffff880148745c90 RSI: ffff880181864a00 RDI: ffff880148745b78 RBP: ffff880148745c48 R08: 0000000000000048 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff880181864a00 R13: ffff880148745c90 R14: 0000000000000048 R15: 0000000000000048 FS: 0000000000000000(0000) GS:ffff88021e200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000088 CR3: 000000020c42c000 CR4: 00000000001407b0 Oops#2 Part7 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Stack: ffff880148745b30 ffffffff810c4af9 0000004848745b30 ffff880181864a00 ffffffff81ffbc40 0000000000000000 ffff880148745c90 ffffffff810a5aab ffff880148745bc0 ffffffff81ffbc40 ffff880148745b60 ffffffff815a9fb8 Call Trace: [] ? finish_task_switch+0x49/0xe0 [] ? lock_timer_base.isra.36+0x2b/0x50 [] ? _raw_spin_unlock_irqrestore+0x18/0x40 [] ? try_to_del_timer_sync+0x4f/0x70 [] ? _raw_spin_unlock_bh+0x1f/0x30 [] kernel_sendmsg+0x37/0x50 [] smb_send_kvec+0xd0/0x1d0 [cifs] [] smb_send_rqst+0x83/0x1f0 [cifs] [] cifs_call_async+0xec/0x1b0 [cifs] [] ? free_rsp_buf+0x40/0x40 [cifs] Oops#2 Part6 [] SMB2_echo+0x8e/0xb0 [cifs] [] cifs_echo_request+0x79/0xa0 [cifs] [] process_one_work+0x173/0x4a0 [] worker_thread+0x121/0x3a0 [] ? manage_workers.isra.27+0x2b0/0x2b0 [] kthread+0xc0/0xd0 [] ? kthread_create_on_node+0x120/0x120 [] ret_from_fork+0x7c/0xb0 [] ? kthread_create_on_node+0x120/0x120 Code: 84 24 b8 00 00 00 4c 89 f1 4c 89 ea 4c 89 e6 48 89 df 4c 89 60 18 48 c7 40 28 00 00 00 00 4c 89 68 30 44 89 70 14 49 8b 44 24 28 90 88 00 00 00 3d ef fd ff ff 74 10 48 8d 65 e0 5b 41 5c 41 RIP [] sock_sendmsg+0x93/0xd0 RSP CR2: 0000000000000088 The client was in the middle of trying to send a frame when the server->ssocket pointer got zeroed out. In most places, that we access that pointer, the srv_mutex is held. There's only one spot that I see that the server->ssocket pointer gets set and the srv_mutex isn't held. This patch corrects that. The upstream bug report was here: https://bugzilla.kernel.org/show_bug.cgi?id=60557 Cc: Reported-by: Oleksii Shevchuk Signed-off-by: Jeff Layton Signed-off-by: Steve French --- fs/cifs/connect.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index d67c550c498..37950c65453 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -379,6 +379,7 @@ cifs_reconnect(struct TCP_Server_Info *server) try_to_freeze(); /* we should try only the port we connected to before */ + mutex_lock(&server->srv_mutex); rc = generic_ip_connect(server); if (rc) { cifs_dbg(FYI, "reconnect error %d\n", rc); @@ -390,6 +391,7 @@ cifs_reconnect(struct TCP_Server_Info *server) server->tcpStatus = CifsNeedNegotiate; spin_unlock(&GlobalMid_Lock); } + mutex_unlock(&server->srv_mutex); } while (server->tcpStatus == CifsNeedReconnect); return rc; -- cgit v1.2.3