4.4-stable review patch. If anyone has any objections, please let me know.
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From: Lin Zhang xiaolou4617@gmail.com
[ Upstream commit a611c58b3d42a92e6b23423e166dd17c0c7fffce ]
This patch fixes the kernel oops when release net_device reference in advance. In function raw_sendmsg(i think the dgram_sendmsg has the same problem), there is a race condition between dev_put and dev_queue_xmit when the device is gong that maybe lead to dev_queue_ximt to see an illegal net_device pointer.
My test kernel is 3.13.0-32 and because i am not have a real 802154 device, so i change lowpan_newlink function to this:
/* find and hold real wpan device */ real_dev = dev_get_by_index(src_net, nla_get_u32(tb[IFLA_LINK])); if (!real_dev) return -ENODEV; // if (real_dev->type != ARPHRD_IEEE802154) { // dev_put(real_dev); // return -EINVAL; // } lowpan_dev_info(dev)->real_dev = real_dev; lowpan_dev_info(dev)->fragment_tag = 0; mutex_init(&lowpan_dev_info(dev)->dev_list_mtx);
Also, in order to simulate preempt, i change the raw_sendmsg function to this:
skb->dev = dev; skb->sk = sk; skb->protocol = htons(ETH_P_IEEE802154); dev_put(dev); //simulate preempt schedule_timeout_uninterruptible(30 * HZ); err = dev_queue_xmit(skb); if (err > 0) err = net_xmit_errno(err);
and this is my userspace test code named test_send_data:
int main(int argc, char **argv) { char buf[127]; int sockfd; sockfd = socket(AF_IEEE802154, SOCK_RAW, 0); if (sockfd < 0) { printf("create sockfd error: %s\n", strerror(errno)); return -1; } send(sockfd, buf, sizeof(buf), 0); return 0; }
This is my test case:
root@zhanglin-x-computer:~/develop/802154# uname -a Linux zhanglin-x-computer 3.13.0-32-generic #57-Ubuntu SMP Tue Jul 15 03:51:08 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux root@zhanglin-x-computer:~/develop/802154# ip link add link eth0 name lowpan0 type lowpan root@zhanglin-x-computer:~/develop/802154# //keep the lowpan0 device down root@zhanglin-x-computer:~/develop/802154# ./test_send_data & //wait a while root@zhanglin-x-computer:~/develop/802154# ip link del link dev lowpan0 //the device is gone //oops [381.303307] general protection fault: 0000 [#1]SMP [381.303407] Modules linked in: af_802154 6lowpan bnep rfcomm bluetooth nls_iso8859_1 snd_hda_codec_hdmi snd_hda_codec_realtek rts5139(C) snd_hda_intel snd_had_codec snd_hwdep snd_pcm snd_page_alloc snd_seq_midi snd_seq_midi_event snd_rawmidi snd_req intel_rapl snd_seq_device coretemp i915 kvm_intel kvm snd_timer snd crct10dif_pclmul crc32_pclmul ghash_clmulni_intel cypted drm_kms_helper drm i2c_algo_bit soundcore video mac_hid parport_pc ppdev ip parport hid_generic usbhid hid ahci r8169 mii libahdi [381.304286] CPU:1 PID: 2524 Commm: 1 Tainted: G C 0 3.13.0-32-generic [381.304409] Hardware name: Haier Haier DT Computer/Haier DT Codputer, BIOS FIBT19H02_X64 06/09/2014 [381.304546] tasks: ffff000096965fc0 ti: ffffB0013779c000 task.ti: ffffB8013779c000 [381.304659] RIP: 0010:[<ffffffff01621fe1>] [<ffffffff81621fe1>] __dev_queue_ximt+0x61/0x500 [381.304798] RSP: 0018:ffffB8013779dca0 EFLAGS: 00010202 [381.304880] RAX: 272b031d57565351 RBX: 0000000000000000 RCX: ffff8800968f1a00 [381.304987] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8800968f1a00 [381.305095] RBP: ffff8e013773dce0 R08: 0000000000000266 R09: 0000000000000004 [381.305202] R10: 0000000000000004 R11: 0000000000000005 R12: ffff88013902e000 [381.305310] R13: 000000000000007f R14: 000000000000007f R15: ffff8800968f1a00 [381.305418] FS: 00007fc57f50f740(0000) GS: ffff88013fc80000(0000) knlGS: 0000000000000000 [381.305540] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [381.305627] CR2: 00007fad0841c000 CR3: 00000001368dd000 CR4: 00000000001007e0 [361.905734] Stack: [381.305768] 00000000002052d0 000000003facb30a ffff88013779dcc0 ffff880137764000 [381.305898] ffff88013779de70 000000000000007f 000000000000007f ffff88013902e000 [381.306026] ffff88013779dcf0 ffffffff81622490 ffff88013779dd39 ffffffffa03af9f1 [381.306155] Call Trace: [381.306202] [<ffffffff81622490>] dev_queue_xmit+0x10/0x20 [381.306294] [<ffffffffa03af9f1>] raw_sendmsg+0x1b1/0x270 [af_802154] [381.306396] [<ffffffffa03af054>] ieee802154_sock_sendmsg+0x14/0x20 [af_802154] [381.306512] [<ffffffff816079eb>] sock_sendmsg+0x8b/0xc0 [381.306600] [<ffffffff811d52a5>] ? __d_alloc+0x25/0x180 [381.306687] [<ffffffff811a1f56>] ? kmem_cache_alloc_trace+0x1c6/0x1f0 [381.306791] [<ffffffff81607b91>] SYSC_sendto+0x121/0x1c0 [381.306878] [<ffffffff8109ddf4>] ? vtime_account_user+x54/0x60 [381.306975] [<ffffffff81020d45>] ? syscall_trace_enter+0x145/0x250 [381.307073] [<ffffffff816086ae>] SyS_sendto+0xe/0x10 [381.307156] [<ffffffff8172c87f>] tracesys+0xe1/0xe6 [381.307233] Code: c6 a1 a4 ff 41 8b 57 78 49 8b 47 20 85 d2 48 8b 80 78 07 00 00 75 21 49 8b 57 18 48 85 d2 74 18 48 85 c0 74 13 8b 92 ac 01 00 00 <3b> 50 10 73 08 8b 44 90 14 41 89 47 78 41 f6 84 24 d5 00 00 00 [381.307801] RIP [<ffffffff81621fe1>] _dev_queue_xmit+0x61/0x500 [381.307901] RSP <ffff88013779dca0> [381.347512] Kernel panic - not syncing: Fatal exception in interrupt [381.347747] drm_kms_helper: panic occurred, switching back to text console
In my opinion, there is always exist a chance that the device is gong before call dev_queue_xmit.
I think the latest kernel is have the same problem and that dev_put should be behind of the dev_queue_xmit.
Signed-off-by: Lin Zhang xiaolou4617@gmail.com Acked-by: Stefan Schmidt stefan@osg.samsung.com Signed-off-by: Marcel Holtmann marcel@holtmann.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ieee802154/socket.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
--- a/net/ieee802154/socket.c +++ b/net/ieee802154/socket.c @@ -302,12 +302,12 @@ static int raw_sendmsg(struct sock *sk, skb->sk = sk; skb->protocol = htons(ETH_P_IEEE802154);
- dev_put(dev); - err = dev_queue_xmit(skb); if (err > 0) err = net_xmit_errno(err);
+ dev_put(dev); + return err ?: size;
out_skb: @@ -689,12 +689,12 @@ static int dgram_sendmsg(struct sock *sk skb->sk = sk; skb->protocol = htons(ETH_P_IEEE802154);
- dev_put(dev); - err = dev_queue_xmit(skb); if (err > 0) err = net_xmit_errno(err);
+ dev_put(dev); + return err ?: size;
out_skb: