diff mbox series

[net] net/smc: fix ref_tracker issue in smc_pnet_add()

Message ID 20220206050516.23178-1-eric.dumazet@gmail.com (mailing list archive)
State Accepted
Commit 28f9222138868899c53e00bc1f910faa55f88546
Delegated to: Netdev Maintainers
Headers show
Series [net] net/smc: fix ref_tracker issue in smc_pnet_add() | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net
netdev/fixes_present success Fixes tag present in non-next series
netdev/subject_prefix success Link
netdev/cover_letter success Single patches do not need cover letters
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers warning 2 maintainers not CCed: linux-s390@vger.kernel.org kgraul@linux.ibm.com
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch warning WARNING: Possible repeated word: 'Google'
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Eric Dumazet Feb. 6, 2022, 5:05 a.m. UTC 
From: Eric Dumazet <edumazet@google.com>

I added the netdev_tracker_alloc() right after ndev was
stored into the newly allocated object:

  new_pe->ndev = ndev;
  if (ndev)
      netdev_tracker_alloc(ndev, &new_pe->dev_tracker, GFP_KERNEL);

But I missed that later, we could end up freeing new_pe,
then calling dev_put(ndev) to release the reference on ndev.

The new_pe->dev_tracker would not be freed.

To solve this issue, move the netdev_tracker_alloc() call to
the point we know for sure new_pe will be kept.

syzbot report (on net-next tree, but the bug is present in net tree)
WARNING: CPU: 0 PID: 6019 at lib/refcount.c:31 refcount_warn_saturate+0xbf/0x1e0 lib/refcount.c:31
Modules linked in:
CPU: 0 PID: 6019 Comm: syz-executor.3 Not tainted 5.17.0-rc2-syzkaller-00650-g5a8fb33e5305 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:refcount_warn_saturate+0xbf/0x1e0 lib/refcount.c:31
Code: 1d f4 70 a0 09 31 ff 89 de e8 4d bc 99 fd 84 db 75 e0 e8 64 b8 99 fd 48 c7 c7 20 0c 06 8a c6 05 d4 70 a0 09 01 e8 9e 4e 28 05 <0f> 0b eb c4 e8 48 b8 99 fd 0f b6 1d c3 70 a0 09 31 ff 89 de e8 18
RSP: 0018:ffffc900043b7400 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000040000 RSI: ffffffff815fb318 RDI: fffff52000876e72
RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff815f507e R11: 0000000000000000 R12: 1ffff92000876e85
R13: 0000000000000000 R14: ffff88805c1c6600 R15: 0000000000000000
FS:  00007f1ef6feb700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2d02b000 CR3: 00000000223f4000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __refcount_dec include/linux/refcount.h:344 [inline]
 refcount_dec include/linux/refcount.h:359 [inline]
 ref_tracker_free+0x53f/0x6c0 lib/ref_tracker.c:119
 netdev_tracker_free include/linux/netdevice.h:3867 [inline]
 dev_put_track include/linux/netdevice.h:3884 [inline]
 dev_put_track include/linux/netdevice.h:3880 [inline]
 dev_put include/linux/netdevice.h:3910 [inline]
 smc_pnet_add_eth net/smc/smc_pnet.c:399 [inline]
 smc_pnet_enter net/smc/smc_pnet.c:493 [inline]
 smc_pnet_add+0x5fc/0x15f0 net/smc/smc_pnet.c:556
 genl_family_rcv_msg_doit+0x228/0x320 net/netlink/genetlink.c:731
 genl_family_rcv_msg net/netlink/genetlink.c:775 [inline]
 genl_rcv_msg+0x328/0x580 net/netlink/genetlink.c:792
 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2494
 genl_rcv+0x24/0x40 net/netlink/genetlink.c:803
 netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline]
 netlink_unicast+0x539/0x7e0 net/netlink/af_netlink.c:1343
 netlink_sendmsg+0x904/0xe00 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:705 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:725
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2413
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2467
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2496
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Fixes: b60645248af3 ("net/smc: add net device tracker to struct smc_pnetentry")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
---
 net/smc/smc_pnet.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

Comments

patchwork-bot+netdevbpf@kernel.org Feb. 6, 2022, 11:10 a.m. UTC | #1 
Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller <davem@davemloft.net>:

On Sat,  5 Feb 2022 21:05:16 -0800 you wrote:
> From: Eric Dumazet <edumazet@google.com>
> 
> I added the netdev_tracker_alloc() right after ndev was
> stored into the newly allocated object:
> 
>   new_pe->ndev = ndev;
>   if (ndev)
>       netdev_tracker_alloc(ndev, &new_pe->dev_tracker, GFP_KERNEL);
> 
> [...]

Here is the summary with links:
  - [net] net/smc: fix ref_tracker issue in smc_pnet_add()
    https://git.kernel.org/netdev/net/c/28f922213886

You are awesome, thank you!
Eric Dumazet Feb. 6, 2022, 2:25 p.m. UTC | #2 
On Sat, Feb 5, 2022 at 9:05 PM Eric Dumazet <eric.dumazet@gmail.com> wrote:
>

>
> diff --git a/net/smc/smc_pnet.c b/net/smc/smc_pnet.c
> index 291f1484a1b74c0a793ab3c4f3ef90804d1f9932..fb6331d97185a5db9b4539e7f081e9fa469bc44b 100644
> --- a/net/smc/smc_pnet.c
> +++ b/net/smc/smc_pnet.c
> @@ -368,9 +368,6 @@ static int smc_pnet_add_eth(struct smc_pnettable *pnettable, struct net *net,
>         new_pe->type = SMC_PNET_ETH;
>         memcpy(new_pe->pnet_name, pnet_name, SMC_MAX_PNETID_LEN);
>         strncpy(new_pe->eth_name, eth_name, IFNAMSIZ);
> -       new_pe->ndev = ndev;
> -       if (ndev)
> -               netdev_tracker_alloc(ndev, &new_pe->dev_tracker, GFP_KERNEL);
>         rc = -EEXIST;
>         new_netdev = true;
>         write_lock(&pnettable->lock);
> @@ -382,6 +379,11 @@ static int smc_pnet_add_eth(struct smc_pnettable *pnettable, struct net *net,
>                 }
>         }
>         if (new_netdev) {
> +               if (ndev) {
> +                       new_pe->ndev = ndev;
> +                       netdev_tracker_alloc(ndev, &new_pe->dev_tracker,
> +                                            GFP_KERNEL);

Oh well, this needs to become GFP_ATOMIC, we are under a write_lock() section.

I will send a fix :/

> +               }
>                 list_add_tail(&new_pe->list, &pnettable->pnetlist);
>                 write_unlock(&pnettable->lock);
>         } else {
> --
> 2.35.0.263.gb82422642f-goog
>
diff mbox series

Patch

diff --git a/net/smc/smc_pnet.c b/net/smc/smc_pnet.c
index 291f1484a1b74c0a793ab3c4f3ef90804d1f9932..fb6331d97185a5db9b4539e7f081e9fa469bc44b 100644
--- a/net/smc/smc_pnet.c
+++ b/net/smc/smc_pnet.c
@@ -368,9 +368,6 @@  static int smc_pnet_add_eth(struct smc_pnettable *pnettable, struct net *net,
 	new_pe->type = SMC_PNET_ETH;
 	memcpy(new_pe->pnet_name, pnet_name, SMC_MAX_PNETID_LEN);
 	strncpy(new_pe->eth_name, eth_name, IFNAMSIZ);
-	new_pe->ndev = ndev;
-	if (ndev)
-		netdev_tracker_alloc(ndev, &new_pe->dev_tracker, GFP_KERNEL);
 	rc = -EEXIST;
 	new_netdev = true;
 	write_lock(&pnettable->lock);
@@ -382,6 +379,11 @@  static int smc_pnet_add_eth(struct smc_pnettable *pnettable, struct net *net,
 		}
 	}
 	if (new_netdev) {
+		if (ndev) {
+			new_pe->ndev = ndev;
+			netdev_tracker_alloc(ndev, &new_pe->dev_tracker,
+					     GFP_KERNEL);
+		}
 		list_add_tail(&new_pe->list, &pnettable->pnetlist);
 		write_unlock(&pnettable->lock);
 	} else {