Hello Andrey, hello Cong,
thanks for catching this issue.
I added lock_sock() and a check for a failing proc_create_data() below.
Can you please check if it solved the issue?
I tested the patched version with the stress tool as advised by Andrey
and did not see any problems in dmesg anymore.
If ok I can provide a proper patch.
Many thanks,
Oliver
diff --git a/net/can/bcm.c b/net/can/bcm.c
index 8e999ff..8af9d25 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -1549,24 +1549,31 @@ static int bcm_connect(struct socket *sock,
struct sockaddr *uaddr, int len,
struct sockaddr_can *addr = (struct sockaddr_can *)uaddr;
struct sock *sk = sock->sk;
struct bcm_sock *bo = bcm_sk(sk);
+ int ret = 0;
if (len < sizeof(*addr))
return -EINVAL;
- if (bo->bound)
- return -EISCONN;
+ lock_sock(sk);
+
+ if (bo->bound) {
+ ret = -EISCONN;
+ goto fail;
+ }
/* bind a device to this socket */
if (addr->can_ifindex) {
struct net_device *dev;
dev = dev_get_by_index(&init_net, addr->can_ifindex);
- if (!dev)
- return -ENODEV;
-
+ if (!dev) {
+ ret = -ENODEV;
+ goto fail;
+ }
if (dev->type != ARPHRD_CAN) {
dev_put(dev);
- return -ENODEV;
+ ret = -ENODEV;
+ goto fail;
}
bo->ifindex = dev->ifindex;
@@ -1577,17 +1584,24 @@ static int bcm_connect(struct socket *sock,
struct sockaddr *uaddr, int len,
bo->ifindex = 0;
}
- bo->bound = 1;
-
if (proc_dir) {
/* unique socket address as filename */
sprintf(bo->procname, "%lu", sock_i_ino(sk));
bo->bcm_proc_read = proc_create_data(bo->procname, 0644,
proc_dir,
&bcm_proc_fops, sk);
+ if (!bo->bcm_proc_read) {
+ ret = -ENOMEM;
+ goto fail;
+ }
}
- return 0;
+ bo->bound = 1;
+
+fail:
+ release_sock(sk);
+
+ return ret;
}
static int bcm_recvmsg(struct socket *sock, struct msghdr *msg, size_t
size,
On 10/24/2016 07:31 PM, Andrey Konovalov wrote:
Hi Cong,
I'm able to reproduce it by running
https://gist.github.com/xairy/33f2eb6bf807b004e643bae36c3d02d7 in a
tight parallel loop with stress
(https://godoc.org/golang.org/x/tools/cmd/stress):
$ gcc -lpthread tmp.c
$ ./stress ./a.out
The C program was generated from the following syzkaller prog:
mmap(&(0x7f0000000000/0x991000)=nil, (0x991000), 0x3, 0x32,
0xffffffffffffffff, 0x0)
socket(0x1d, 0x80002, 0x2)
r0 = socket(0x1d, 0x80002, 0x2)
connect$nfc_llcp(r0, &(0x7f000000c000)={0x27, 0x100000000, 0x0, 0x5,
0x100000000, 0x1,
"341b3a01b257849ca1d7d1ff9f999d8127b185f88d1d775d59c88a3aa6a8ddacdf2bdc324ea6578a21b85114610186c3817c34b05eaffd2c3f54f57fa81ba0",
0x1ff}, 0x60)
connect$nfc_llcp(r0, &(0x7f0000991000-0x60)={0x27, 0x100000000, 0x1,
0x5, 0xfffffffffffffffd, 0x0,
"341b3a01b257849ca1d7d1ff9f999d8127b185f88d1d775dbec88a3aa6a8ddacdf2bdc324ea6578a21b85114610186c3817c34b05eaffd2c3f54f57fa81ba0",
0x1ff}, 0x60)
Unfortunately I wasn't able to create a simpler reproducer.
Thanks!
On Mon, Oct 24, 2016 at 6:58 PM, Cong Wang <xiyou.wangc...@gmail.com> wrote:
On Mon, Oct 24, 2016 at 9:21 AM, Andrey Konovalov <andreyk...@google.com> wrote:
Hi,
I've got the following error report while running the syzkaller fuzzer:
WARNING: CPU: 0 PID: 32451 at fs/proc/generic.c:345 proc_register+0x25e/0x300
proc_dir_entry 'can-bcm/249757' already registered
Kernel panic - not syncing: panic_on_warn set ...
Looks like we have two problems here:
1) A check for bo->bcm_proc_read != NULL seems missing
2) We need to lock the sock in bcm_connect().
I will work on a patch. Meanwhile, it would help a lot if you could provide
a reproducer.
Thanks!
