diff mbox series

can: j1939: Initialize unused data in j1939_send_one()

Message ID 20240512160307.2604215-1-syoshida@redhat.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series can: j1939: Initialize unused data in j1939_send_one() | expand

Checks

Context Check Description
netdev/tree_selection success Series ignored based on subject, async

Commit Message

Shigeru Yoshida May 12, 2024, 4:03 p.m. UTC 
syzbot reported kernel-infoleak in raw_recvmsg() [1]. j1939_send_one()
creates full frame including unused data, but it doesn't initialize it.
This causes the kernel-infoleak issue. Fix this by initializing unused
data.

[1]
BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:114 [inline]
BUG: KMSAN: kernel-infoleak in copy_to_user_iter lib/iov_iter.c:24 [inline]
BUG: KMSAN: kernel-infoleak in iterate_ubuf include/linux/iov_iter.h:29 [inline]
BUG: KMSAN: kernel-infoleak in iterate_and_advance2 include/linux/iov_iter.h:245 [inline]
BUG: KMSAN: kernel-infoleak in iterate_and_advance include/linux/iov_iter.h:271 [inline]
BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x366/0x2520 lib/iov_iter.c:185
 instrument_copy_to_user include/linux/instrumented.h:114 [inline]
 copy_to_user_iter lib/iov_iter.c:24 [inline]
 iterate_ubuf include/linux/iov_iter.h:29 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:245 [inline]
 iterate_and_advance include/linux/iov_iter.h:271 [inline]
 _copy_to_iter+0x366/0x2520 lib/iov_iter.c:185
 copy_to_iter include/linux/uio.h:196 [inline]
 memcpy_to_msg include/linux/skbuff.h:4113 [inline]
 raw_recvmsg+0x2b8/0x9e0 net/can/raw.c:1008
 sock_recvmsg_nosec net/socket.c:1046 [inline]
 sock_recvmsg+0x2c4/0x340 net/socket.c:1068
 ____sys_recvmsg+0x18a/0x620 net/socket.c:2803
 ___sys_recvmsg+0x223/0x840 net/socket.c:2845
 do_recvmmsg+0x4fc/0xfd0 net/socket.c:2939
 __sys_recvmmsg net/socket.c:3018 [inline]
 __do_sys_recvmmsg net/socket.c:3041 [inline]
 __se_sys_recvmmsg net/socket.c:3034 [inline]
 __x64_sys_recvmmsg+0x397/0x490 net/socket.c:3034
 x64_sys_call+0xf6c/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:300
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:3804 [inline]
 slab_alloc_node mm/slub.c:3845 [inline]
 kmem_cache_alloc_node+0x613/0xc50 mm/slub.c:3888
 kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:577
 __alloc_skb+0x35b/0x7a0 net/core/skbuff.c:668
 alloc_skb include/linux/skbuff.h:1313 [inline]
 alloc_skb_with_frags+0xc8/0xbf0 net/core/skbuff.c:6504
 sock_alloc_send_pskb+0xa81/0xbf0 net/core/sock.c:2795
 sock_alloc_send_skb include/net/sock.h:1842 [inline]
 j1939_sk_alloc_skb net/can/j1939/socket.c:878 [inline]
 j1939_sk_send_loop net/can/j1939/socket.c:1142 [inline]
 j1939_sk_sendmsg+0xc0a/0x2730 net/can/j1939/socket.c:1277
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x30f/0x380 net/socket.c:745
 ____sys_sendmsg+0x877/0xb60 net/socket.c:2584
 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638
 __sys_sendmsg net/socket.c:2667 [inline]
 __do_sys_sendmsg net/socket.c:2676 [inline]
 __se_sys_sendmsg net/socket.c:2674 [inline]
 __x64_sys_sendmsg+0x307/0x4a0 net/socket.c:2674
 x64_sys_call+0xc4b/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Bytes 12-15 of 16 are uninitialized
Memory access of size 16 starts at ffff888120969690
Data copied to user address 00000000200017c0

CPU: 1 PID: 5050 Comm: syz-executor198 Not tainted 6.9.0-rc5-syzkaller-00031-g71b1543c83d6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024

Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Reported-and-tested-by: syzbot+5681e40d297b30f5b513@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=5681e40d297b30f5b513
Signed-off-by: Shigeru Yoshida <syoshida@redhat.com>
---
 net/can/j1939/main.c | 3 +++
 1 file changed, 3 insertions(+)

Comments

Oleksij Rempel May 13, 2024, 7:14 a.m. UTC | #1 
Hi,

On Mon, May 13, 2024 at 01:03:07AM +0900, Shigeru Yoshida wrote:
> syzbot reported kernel-infoleak in raw_recvmsg() [1]. j1939_send_one()
> creates full frame including unused data, but it doesn't initialize it.
> This causes the kernel-infoleak issue. Fix this by initializing unused
> data.
> 
> [1]
> BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:114 [inline]
> BUG: KMSAN: kernel-infoleak in copy_to_user_iter lib/iov_iter.c:24 [inline]
> BUG: KMSAN: kernel-infoleak in iterate_ubuf include/linux/iov_iter.h:29 [inline]
> BUG: KMSAN: kernel-infoleak in iterate_and_advance2 include/linux/iov_iter.h:245 [inline]
> BUG: KMSAN: kernel-infoleak in iterate_and_advance include/linux/iov_iter.h:271 [inline]
> BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x366/0x2520 lib/iov_iter.c:185
>  instrument_copy_to_user include/linux/instrumented.h:114 [inline]
>  copy_to_user_iter lib/iov_iter.c:24 [inline]
>  iterate_ubuf include/linux/iov_iter.h:29 [inline]
>  iterate_and_advance2 include/linux/iov_iter.h:245 [inline]
>  iterate_and_advance include/linux/iov_iter.h:271 [inline]
>  _copy_to_iter+0x366/0x2520 lib/iov_iter.c:185
>  copy_to_iter include/linux/uio.h:196 [inline]
>  memcpy_to_msg include/linux/skbuff.h:4113 [inline]
>  raw_recvmsg+0x2b8/0x9e0 net/can/raw.c:1008
>  sock_recvmsg_nosec net/socket.c:1046 [inline]
>  sock_recvmsg+0x2c4/0x340 net/socket.c:1068
>  ____sys_recvmsg+0x18a/0x620 net/socket.c:2803
>  ___sys_recvmsg+0x223/0x840 net/socket.c:2845
>  do_recvmmsg+0x4fc/0xfd0 net/socket.c:2939
>  __sys_recvmmsg net/socket.c:3018 [inline]
>  __do_sys_recvmmsg net/socket.c:3041 [inline]
>  __se_sys_recvmmsg net/socket.c:3034 [inline]
>  __x64_sys_recvmmsg+0x397/0x490 net/socket.c:3034
>  x64_sys_call+0xf6c/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:300
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> 
> Uninit was created at:
>  slab_post_alloc_hook mm/slub.c:3804 [inline]
>  slab_alloc_node mm/slub.c:3845 [inline]
>  kmem_cache_alloc_node+0x613/0xc50 mm/slub.c:3888
>  kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:577
>  __alloc_skb+0x35b/0x7a0 net/core/skbuff.c:668
>  alloc_skb include/linux/skbuff.h:1313 [inline]
>  alloc_skb_with_frags+0xc8/0xbf0 net/core/skbuff.c:6504
>  sock_alloc_send_pskb+0xa81/0xbf0 net/core/sock.c:2795
>  sock_alloc_send_skb include/net/sock.h:1842 [inline]
>  j1939_sk_alloc_skb net/can/j1939/socket.c:878 [inline]
>  j1939_sk_send_loop net/can/j1939/socket.c:1142 [inline]
>  j1939_sk_sendmsg+0xc0a/0x2730 net/can/j1939/socket.c:1277
>  sock_sendmsg_nosec net/socket.c:730 [inline]
>  __sock_sendmsg+0x30f/0x380 net/socket.c:745
>  ____sys_sendmsg+0x877/0xb60 net/socket.c:2584
>  ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638
>  __sys_sendmsg net/socket.c:2667 [inline]
>  __do_sys_sendmsg net/socket.c:2676 [inline]
>  __se_sys_sendmsg net/socket.c:2674 [inline]
>  __x64_sys_sendmsg+0x307/0x4a0 net/socket.c:2674
>  x64_sys_call+0xc4b/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:47
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> 
> Bytes 12-15 of 16 are uninitialized
> Memory access of size 16 starts at ffff888120969690
> Data copied to user address 00000000200017c0
> 
> CPU: 1 PID: 5050 Comm: syz-executor198 Not tainted 6.9.0-rc5-syzkaller-00031-g71b1543c83d6 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
> 
> Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
> Reported-and-tested-by: syzbot+5681e40d297b30f5b513@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=5681e40d297b30f5b513
> Signed-off-by: Shigeru Yoshida <syoshida@redhat.com>

Thank you for your investigation!

> ---
>  net/can/j1939/main.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/net/can/j1939/main.c b/net/can/j1939/main.c
> index a6fb89fa6278..df01628c6509 100644
> --- a/net/can/j1939/main.c
> +++ b/net/can/j1939/main.c
> @@ -344,6 +344,9 @@ int j1939_send_one(struct j1939_priv *priv, struct sk_buff *skb)
>  	/* make it a full can frame again */
>  	skb_put(skb, J1939_CAN_FTR + (8 - dlc));
>  
> +	/* initialize unused data  */
> +	memset(cf->data + dlc, 0, 8 - dlc);
> +
>  	canid = CAN_EFF_FLAG |
>  		(skcb->priority << 26) |
>  		(skcb->addr.pgn << 8) |
> -- 
> 2.44.0

Can you please change it to:

--- a/net/can/j1939/main.c
+++ b/net/can/j1939/main.c
@@ -30,10 +30,6 @@ MODULE_ALIAS("can-proto-" __stringify(CAN_J1939));
 /* CAN_HDR: #bytes before can_frame data part */
 #define J1939_CAN_HDR (offsetof(struct can_frame, data))
 
-/* CAN_FTR: #bytes beyond data part */
-#define J1939_CAN_FTR (sizeof(struct can_frame) - J1939_CAN_HDR - \
-		 sizeof(((struct can_frame *)0)->data))
-
 /* lowest layer */
 static void j1939_can_recv(struct sk_buff *iskb, void *data)
 {
@@ -342,7 +338,7 @@ int j1939_send_one(struct j1939_priv *priv, struct sk_buff *skb)
 	memset(cf, 0, J1939_CAN_HDR);
 
 	/* make it a full can frame again */
-	skb_put(skb, J1939_CAN_FTR + (8 - dlc));
+	skb_put_zero(skb, 8 - dlc);
 
 	canid = CAN_EFF_FLAG |
 		(skcb->priority << 26) |

With this change included, you can add my:
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>

Regards,
Oleksij
Shigeru Yoshida May 16, 2024, 1:51 a.m. UTC | #2 
On Mon, 13 May 2024 09:14:21 +0200, Oleksij Rempel wrote:
> Hi,
> 
> On Mon, May 13, 2024 at 01:03:07AM +0900, Shigeru Yoshida wrote:
>> syzbot reported kernel-infoleak in raw_recvmsg() [1]. j1939_send_one()
>> creates full frame including unused data, but it doesn't initialize it.
>> This causes the kernel-infoleak issue. Fix this by initializing unused
>> data.
>> 
>> [1]
>> BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:114 [inline]
>> BUG: KMSAN: kernel-infoleak in copy_to_user_iter lib/iov_iter.c:24 [inline]
>> BUG: KMSAN: kernel-infoleak in iterate_ubuf include/linux/iov_iter.h:29 [inline]
>> BUG: KMSAN: kernel-infoleak in iterate_and_advance2 include/linux/iov_iter.h:245 [inline]
>> BUG: KMSAN: kernel-infoleak in iterate_and_advance include/linux/iov_iter.h:271 [inline]
>> BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x366/0x2520 lib/iov_iter.c:185
>>  instrument_copy_to_user include/linux/instrumented.h:114 [inline]
>>  copy_to_user_iter lib/iov_iter.c:24 [inline]
>>  iterate_ubuf include/linux/iov_iter.h:29 [inline]
>>  iterate_and_advance2 include/linux/iov_iter.h:245 [inline]
>>  iterate_and_advance include/linux/iov_iter.h:271 [inline]
>>  _copy_to_iter+0x366/0x2520 lib/iov_iter.c:185
>>  copy_to_iter include/linux/uio.h:196 [inline]
>>  memcpy_to_msg include/linux/skbuff.h:4113 [inline]
>>  raw_recvmsg+0x2b8/0x9e0 net/can/raw.c:1008
>>  sock_recvmsg_nosec net/socket.c:1046 [inline]
>>  sock_recvmsg+0x2c4/0x340 net/socket.c:1068
>>  ____sys_recvmsg+0x18a/0x620 net/socket.c:2803
>>  ___sys_recvmsg+0x223/0x840 net/socket.c:2845
>>  do_recvmmsg+0x4fc/0xfd0 net/socket.c:2939
>>  __sys_recvmmsg net/socket.c:3018 [inline]
>>  __do_sys_recvmmsg net/socket.c:3041 [inline]
>>  __se_sys_recvmmsg net/socket.c:3034 [inline]
>>  __x64_sys_recvmmsg+0x397/0x490 net/socket.c:3034
>>  x64_sys_call+0xf6c/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:300
>>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>>  do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
>>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>> 
>> Uninit was created at:
>>  slab_post_alloc_hook mm/slub.c:3804 [inline]
>>  slab_alloc_node mm/slub.c:3845 [inline]
>>  kmem_cache_alloc_node+0x613/0xc50 mm/slub.c:3888
>>  kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:577
>>  __alloc_skb+0x35b/0x7a0 net/core/skbuff.c:668
>>  alloc_skb include/linux/skbuff.h:1313 [inline]
>>  alloc_skb_with_frags+0xc8/0xbf0 net/core/skbuff.c:6504
>>  sock_alloc_send_pskb+0xa81/0xbf0 net/core/sock.c:2795
>>  sock_alloc_send_skb include/net/sock.h:1842 [inline]
>>  j1939_sk_alloc_skb net/can/j1939/socket.c:878 [inline]
>>  j1939_sk_send_loop net/can/j1939/socket.c:1142 [inline]
>>  j1939_sk_sendmsg+0xc0a/0x2730 net/can/j1939/socket.c:1277
>>  sock_sendmsg_nosec net/socket.c:730 [inline]
>>  __sock_sendmsg+0x30f/0x380 net/socket.c:745
>>  ____sys_sendmsg+0x877/0xb60 net/socket.c:2584
>>  ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638
>>  __sys_sendmsg net/socket.c:2667 [inline]
>>  __do_sys_sendmsg net/socket.c:2676 [inline]
>>  __se_sys_sendmsg net/socket.c:2674 [inline]
>>  __x64_sys_sendmsg+0x307/0x4a0 net/socket.c:2674
>>  x64_sys_call+0xc4b/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:47
>>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>>  do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
>>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>> 
>> Bytes 12-15 of 16 are uninitialized
>> Memory access of size 16 starts at ffff888120969690
>> Data copied to user address 00000000200017c0
>> 
>> CPU: 1 PID: 5050 Comm: syz-executor198 Not tainted 6.9.0-rc5-syzkaller-00031-g71b1543c83d6 #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
>> 
>> Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
>> Reported-and-tested-by: syzbot+5681e40d297b30f5b513@syzkaller.appspotmail.com
>> Closes: https://syzkaller.appspot.com/bug?extid=5681e40d297b30f5b513
>> Signed-off-by: Shigeru Yoshida <syoshida@redhat.com>
> 
> Thank you for your investigation!
> 
>> ---
>>  net/can/j1939/main.c | 3 +++
>>  1 file changed, 3 insertions(+)
>> 
>> diff --git a/net/can/j1939/main.c b/net/can/j1939/main.c
>> index a6fb89fa6278..df01628c6509 100644
>> --- a/net/can/j1939/main.c
>> +++ b/net/can/j1939/main.c
>> @@ -344,6 +344,9 @@ int j1939_send_one(struct j1939_priv *priv, struct sk_buff *skb)
>>  	/* make it a full can frame again */
>>  	skb_put(skb, J1939_CAN_FTR + (8 - dlc));
>>  
>> +	/* initialize unused data  */
>> +	memset(cf->data + dlc, 0, 8 - dlc);
>> +
>>  	canid = CAN_EFF_FLAG |
>>  		(skcb->priority << 26) |
>>  		(skcb->addr.pgn << 8) |
>> -- 
>> 2.44.0
> 
> Can you please change it to:
> 
> --- a/net/can/j1939/main.c
> +++ b/net/can/j1939/main.c
> @@ -30,10 +30,6 @@ MODULE_ALIAS("can-proto-" __stringify(CAN_J1939));
>  /* CAN_HDR: #bytes before can_frame data part */
>  #define J1939_CAN_HDR (offsetof(struct can_frame, data))
>  
> -/* CAN_FTR: #bytes beyond data part */
> -#define J1939_CAN_FTR (sizeof(struct can_frame) - J1939_CAN_HDR - \
> -		 sizeof(((struct can_frame *)0)->data))
> -
>  /* lowest layer */
>  static void j1939_can_recv(struct sk_buff *iskb, void *data)
>  {
> @@ -342,7 +338,7 @@ int j1939_send_one(struct j1939_priv *priv, struct sk_buff *skb)
>  	memset(cf, 0, J1939_CAN_HDR);
>  
>  	/* make it a full can frame again */
> -	skb_put(skb, J1939_CAN_FTR + (8 - dlc));
> +	skb_put_zero(skb, 8 - dlc);
>  
>  	canid = CAN_EFF_FLAG |
>  		(skcb->priority << 26) |
> 
> With this change included, you can add my:
> Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>

Thank you for your feedback! I will send v2 patch with the above
changes you suggested.

Thanks
Shigeru

> 
> Regards,
> Oleksij
> -- 
> Pengutronix e.K.                           |                             |
> Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
> 31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
> Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |
>
diff mbox series

Patch

diff --git a/net/can/j1939/main.c b/net/can/j1939/main.c
index a6fb89fa6278..df01628c6509 100644
--- a/net/can/j1939/main.c
+++ b/net/can/j1939/main.c
@@ -344,6 +344,9 @@  int j1939_send_one(struct j1939_priv *priv, struct sk_buff *skb)
 	/* make it a full can frame again */
 	skb_put(skb, J1939_CAN_FTR + (8 - dlc));
 
+	/* initialize unused data  */
+	memset(cf->data + dlc, 0, 8 - dlc);
+
 	canid = CAN_EFF_FLAG |
 		(skcb->priority << 26) |
 		(skcb->addr.pgn << 8) |