[PATCH-next] nbd: fix incomplete validation of ioctl arg

[PATCH-next] nbd: fix incomplete validation of ioctl arg

[Zhong Jinghua]

We tested and found an alarm caused by nbd_ioctl arg without verification.
The UBSAN warning calltrace like below:

UBSAN: Undefined behaviour in fs/buffer.c:1709:35
signed integer overflow:
-9223372036854775808 - 1 cannot be represented in type 'long long int'
CPU: 3 PID: 2523 Comm: syz-executor.0 Not tainted 4.19.90 #1
Hardware name: linux,dummy-virt (DT)
Call trace:
 dump_backtrace+0x0/0x3f0 arch/arm64/kernel/time.c:78
 show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x170/0x1dc lib/dump_stack.c:118
 ubsan_epilogue+0x18/0xb4 lib/ubsan.c:161
 handle_overflow+0x188/0x1dc lib/ubsan.c:192
 __ubsan_handle_sub_overflow+0x34/0x44 lib/ubsan.c:206
 __block_write_full_page+0x94c/0xa20 fs/buffer.c:1709
 block_write_full_page+0x1f0/0x280 fs/buffer.c:2934
 blkdev_writepage+0x34/0x40 fs/block_dev.c:607
 __writepage+0x68/0xe8 mm/page-writeback.c:2305
 write_cache_pages+0x44c/0xc70 mm/page-writeback.c:2240
 generic_writepages+0xdc/0x148 mm/page-writeback.c:2329
 blkdev_writepages+0x2c/0x38 fs/block_dev.c:2114
 do_writepages+0xd4/0x250 mm/page-writeback.c:2344

The reason for triggering this warning is __block_write_full_page()
-> i_size_read(inode) - 1 overflow.
inode->i_size is assigned in __nbd_ioctl() -> nbd_set_size() -> bytesize.
We think it is necessary to limit the size of arg to prevent errors.

Moreover, __nbd_ioctl() -> nbd_add_socket(), arg will be cast to int.
Assuming the value of arg is 0x80000000000000001) (on a 64-bit machine),
it will become 1 after the coercion, which will return unexpected results.

Fix it by adding checks to prevent passing in too large numbers.

Signed-off-by: Zhong Jinghua <zhongjinghua@huawei.com>
---
 drivers/block/nbd.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 592cfa8b765a..e1c954094b6c 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -325,6 +325,9 @@ static int nbd_set_size(struct nbd_device *nbd, loff_t bytesize,
 	if (blk_validate_block_size(blksize))
 		return -EINVAL;
 
+	if (bytesize < 0)
+		return -EINVAL;
+
 	nbd->config->bytesize = bytesize;
 	nbd->config->blksize_bits = __ffs(blksize);
 
@@ -1111,6 +1114,9 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
 	struct nbd_sock *nsock;
 	int err;
 
+	/* Arg will be cast to int, check it to avoid overflow */
+	if (arg > INT_MAX)
+		return -EINVAL;
 	sock = nbd_get_socket(nbd, arg, &err);
 	if (!sock)
 		return err;
-- 
2.31.1

Re: [PATCH-next] nbd: fix incomplete validation of ioctl arg

[zhongjinghua]

ping...

Hello，

Anyone looking this？

在 2023/2/6 22:58, Zhong Jinghua 写道:
> We tested and found an alarm caused by nbd_ioctl arg without verification.
> The UBSAN warning calltrace like below:
>
> UBSAN: Undefined behaviour in fs/buffer.c:1709:35
> signed integer overflow:
> -9223372036854775808 - 1 cannot be represented in type 'long long int'
> CPU: 3 PID: 2523 Comm: syz-executor.0 Not tainted 4.19.90 #1
> Hardware name: linux,dummy-virt (DT)
> Call trace:
>   dump_backtrace+0x0/0x3f0 arch/arm64/kernel/time.c:78
>   show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158
>   __dump_stack lib/dump_stack.c:77 [inline]
>   dump_stack+0x170/0x1dc lib/dump_stack.c:118
>   ubsan_epilogue+0x18/0xb4 lib/ubsan.c:161
>   handle_overflow+0x188/0x1dc lib/ubsan.c:192
>   __ubsan_handle_sub_overflow+0x34/0x44 lib/ubsan.c:206
>   __block_write_full_page+0x94c/0xa20 fs/buffer.c:1709
>   block_write_full_page+0x1f0/0x280 fs/buffer.c:2934
>   blkdev_writepage+0x34/0x40 fs/block_dev.c:607
>   __writepage+0x68/0xe8 mm/page-writeback.c:2305
>   write_cache_pages+0x44c/0xc70 mm/page-writeback.c:2240
>   generic_writepages+0xdc/0x148 mm/page-writeback.c:2329
>   blkdev_writepages+0x2c/0x38 fs/block_dev.c:2114
>   do_writepages+0xd4/0x250 mm/page-writeback.c:2344
>
> The reason for triggering this warning is __block_write_full_page()
> -> i_size_read(inode) - 1 overflow.
> inode->i_size is assigned in __nbd_ioctl() -> nbd_set_size() -> bytesize.
> We think it is necessary to limit the size of arg to prevent errors.
>
> Moreover, __nbd_ioctl() -> nbd_add_socket(), arg will be cast to int.
> Assuming the value of arg is 0x80000000000000001) (on a 64-bit machine),
> it will become 1 after the coercion, which will return unexpected results.
>
> Fix it by adding checks to prevent passing in too large numbers.
>
> Signed-off-by: Zhong Jinghua <zhongjinghua@huawei.com>
> ---
>   drivers/block/nbd.c | 6 ++++++
>   1 file changed, 6 insertions(+)
>
> diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
> index 592cfa8b765a..e1c954094b6c 100644
> --- a/drivers/block/nbd.c
> +++ b/drivers/block/nbd.c
> @@ -325,6 +325,9 @@ static int nbd_set_size(struct nbd_device *nbd, loff_t bytesize,
>   	if (blk_validate_block_size(blksize))
>   		return -EINVAL;
>   
> +	if (bytesize < 0)
> +		return -EINVAL;
> +
>   	nbd->config->bytesize = bytesize;
>   	nbd->config->blksize_bits = __ffs(blksize);
>   
> @@ -1111,6 +1114,9 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
>   	struct nbd_sock *nsock;
>   	int err;
>   
> +	/* Arg will be cast to int, check it to avoid overflow */
> +	if (arg > INT_MAX)
> +		return -EINVAL;
>   	sock = nbd_get_socket(nbd, arg, &err);
>   	if (!sock)
>   		return err;

Re: [PATCH-next] nbd: fix incomplete validation of ioctl arg

[zhongjinghua]

ping...

Hello

Anyone looking this？

在 2023/2/6 22:58, Zhong Jinghua 写道:
> We tested and found an alarm caused by nbd_ioctl arg without verification.
> The UBSAN warning calltrace like below:
>
> UBSAN: Undefined behaviour in fs/buffer.c:1709:35
> signed integer overflow:
> -9223372036854775808 - 1 cannot be represented in type 'long long int'
> CPU: 3 PID: 2523 Comm: syz-executor.0 Not tainted 4.19.90 #1
> Hardware name: linux,dummy-virt (DT)
> Call trace:
>   dump_backtrace+0x0/0x3f0 arch/arm64/kernel/time.c:78
>   show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158
>   __dump_stack lib/dump_stack.c:77 [inline]
>   dump_stack+0x170/0x1dc lib/dump_stack.c:118
>   ubsan_epilogue+0x18/0xb4 lib/ubsan.c:161
>   handle_overflow+0x188/0x1dc lib/ubsan.c:192
>   __ubsan_handle_sub_overflow+0x34/0x44 lib/ubsan.c:206
>   __block_write_full_page+0x94c/0xa20 fs/buffer.c:1709
>   block_write_full_page+0x1f0/0x280 fs/buffer.c:2934
>   blkdev_writepage+0x34/0x40 fs/block_dev.c:607
>   __writepage+0x68/0xe8 mm/page-writeback.c:2305
>   write_cache_pages+0x44c/0xc70 mm/page-writeback.c:2240
>   generic_writepages+0xdc/0x148 mm/page-writeback.c:2329
>   blkdev_writepages+0x2c/0x38 fs/block_dev.c:2114
>   do_writepages+0xd4/0x250 mm/page-writeback.c:2344
>
> The reason for triggering this warning is __block_write_full_page()
> -> i_size_read(inode) - 1 overflow.
> inode->i_size is assigned in __nbd_ioctl() -> nbd_set_size() -> bytesize.
> We think it is necessary to limit the size of arg to prevent errors.
>
> Moreover, __nbd_ioctl() -> nbd_add_socket(), arg will be cast to int.
> Assuming the value of arg is 0x80000000000000001) (on a 64-bit machine),
> it will become 1 after the coercion, which will return unexpected results.
>
> Fix it by adding checks to prevent passing in too large numbers.
>
> Signed-off-by: Zhong Jinghua <zhongjinghua@huawei.com>
> ---
>   drivers/block/nbd.c | 6 ++++++
>   1 file changed, 6 insertions(+)
>
> diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
> index 592cfa8b765a..e1c954094b6c 100644
> --- a/drivers/block/nbd.c
> +++ b/drivers/block/nbd.c
> @@ -325,6 +325,9 @@ static int nbd_set_size(struct nbd_device *nbd, loff_t bytesize,
>   	if (blk_validate_block_size(blksize))
>   		return -EINVAL;
>   
> +	if (bytesize < 0)
> +		return -EINVAL;
> +
>   	nbd->config->bytesize = bytesize;
>   	nbd->config->blksize_bits = __ffs(blksize);
>   
> @@ -1111,6 +1114,9 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
>   	struct nbd_sock *nsock;
>   	int err;
>   
> +	/* Arg will be cast to int, check it to avoid overflow */
> +	if (arg > INT_MAX)
> +		return -EINVAL;
>   	sock = nbd_get_socket(nbd, arg, &err);
>   	if (!sock)
>   		return err;

Re: [PATCH-next] nbd: fix incomplete validation of ioctl arg

[zhongjinghua]

ping...

Hello

Anyone looking this？

在 2023/3/14 15:10, zhongjinghua 写道:
> ping...
>
> Hello
>
> Anyone looking this？
>
> 在 2023/2/6 22:58, Zhong Jinghua 写道:
>> We tested and found an alarm caused by nbd_ioctl arg without 
>> verification.
>> The UBSAN warning calltrace like below:
>>
>> UBSAN: Undefined behaviour in fs/buffer.c:1709:35
>> signed integer overflow:
>> -9223372036854775808 - 1 cannot be represented in type 'long long int'
>> CPU: 3 PID: 2523 Comm: syz-executor.0 Not tainted 4.19.90 #1
>> Hardware name: linux,dummy-virt (DT)
>> Call trace:
>>   dump_backtrace+0x0/0x3f0 arch/arm64/kernel/time.c:78
>>   show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158
>>   __dump_stack lib/dump_stack.c:77 [inline]
>>   dump_stack+0x170/0x1dc lib/dump_stack.c:118
>>   ubsan_epilogue+0x18/0xb4 lib/ubsan.c:161
>>   handle_overflow+0x188/0x1dc lib/ubsan.c:192
>>   __ubsan_handle_sub_overflow+0x34/0x44 lib/ubsan.c:206
>>   __block_write_full_page+0x94c/0xa20 fs/buffer.c:1709
>>   block_write_full_page+0x1f0/0x280 fs/buffer.c:2934
>>   blkdev_writepage+0x34/0x40 fs/block_dev.c:607
>>   __writepage+0x68/0xe8 mm/page-writeback.c:2305
>>   write_cache_pages+0x44c/0xc70 mm/page-writeback.c:2240
>>   generic_writepages+0xdc/0x148 mm/page-writeback.c:2329
>>   blkdev_writepages+0x2c/0x38 fs/block_dev.c:2114
>>   do_writepages+0xd4/0x250 mm/page-writeback.c:2344
>>
>> The reason for triggering this warning is __block_write_full_page()
>> -> i_size_read(inode) - 1 overflow.
>> inode->i_size is assigned in __nbd_ioctl() -> nbd_set_size() -> 
>> bytesize.
>> We think it is necessary to limit the size of arg to prevent errors.
>>
>> Moreover, __nbd_ioctl() -> nbd_add_socket(), arg will be cast to int.
>> Assuming the value of arg is 0x80000000000000001) (on a 64-bit machine),
>> it will become 1 after the coercion, which will return unexpected 
>> results.
>>
>> Fix it by adding checks to prevent passing in too large numbers.
>>
>> Signed-off-by: Zhong Jinghua <zhongjinghua@huawei.com>
>> ---
>>   drivers/block/nbd.c | 6 ++++++
>>   1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
>> index 592cfa8b765a..e1c954094b6c 100644
>> --- a/drivers/block/nbd.c
>> +++ b/drivers/block/nbd.c
>> @@ -325,6 +325,9 @@ static int nbd_set_size(struct nbd_device *nbd, 
>> loff_t bytesize,
>>       if (blk_validate_block_size(blksize))
>>           return -EINVAL;
>>   +    if (bytesize < 0)
>> +        return -EINVAL;
>> +
>>       nbd->config->bytesize = bytesize;
>>       nbd->config->blksize_bits = __ffs(blksize);
>>   @@ -1111,6 +1114,9 @@ static int nbd_add_socket(struct nbd_device 
>> *nbd, unsigned long arg,
>>       struct nbd_sock *nsock;
>>       int err;
>>   +    /* Arg will be cast to int, check it to avoid overflow */
>> +    if (arg > INT_MAX)
>> +        return -EINVAL;
>>       sock = nbd_get_socket(nbd, arg, &err);
>>       if (!sock)
>>           return err;

Re: [PATCH-next] nbd: fix incomplete validation of ioctl arg

[Yu Kuai]

在 2023/02/06 22:58, Zhong Jinghua 写道:
> We tested and found an alarm caused by nbd_ioctl arg without verification.
> The UBSAN warning calltrace like below:
> 
> UBSAN: Undefined behaviour in fs/buffer.c:1709:35
> signed integer overflow:
> -9223372036854775808 - 1 cannot be represented in type 'long long int'
> CPU: 3 PID: 2523 Comm: syz-executor.0 Not tainted 4.19.90 #1
> Hardware name: linux,dummy-virt (DT)
> Call trace:
>   dump_backtrace+0x0/0x3f0 arch/arm64/kernel/time.c:78
>   show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158
>   __dump_stack lib/dump_stack.c:77 [inline]
>   dump_stack+0x170/0x1dc lib/dump_stack.c:118
>   ubsan_epilogue+0x18/0xb4 lib/ubsan.c:161
>   handle_overflow+0x188/0x1dc lib/ubsan.c:192
>   __ubsan_handle_sub_overflow+0x34/0x44 lib/ubsan.c:206
>   __block_write_full_page+0x94c/0xa20 fs/buffer.c:1709
>   block_write_full_page+0x1f0/0x280 fs/buffer.c:2934
>   blkdev_writepage+0x34/0x40 fs/block_dev.c:607
>   __writepage+0x68/0xe8 mm/page-writeback.c:2305
>   write_cache_pages+0x44c/0xc70 mm/page-writeback.c:2240
>   generic_writepages+0xdc/0x148 mm/page-writeback.c:2329
>   blkdev_writepages+0x2c/0x38 fs/block_dev.c:2114
>   do_writepages+0xd4/0x250 mm/page-writeback.c:2344
> 
> The reason for triggering this warning is __block_write_full_page()
> -> i_size_read(inode) - 1 overflow.
> inode->i_size is assigned in __nbd_ioctl() -> nbd_set_size() -> bytesize.
> We think it is necessary to limit the size of arg to prevent errors.
> 
> Moreover, __nbd_ioctl() -> nbd_add_socket(), arg will be cast to int.
> Assuming the value of arg is 0x80000000000000001) (on a 64-bit machine),
> it will become 1 after the coercion, which will return unexpected results.
> 
> Fix it by adding checks to prevent passing in too large numbers.

Looks good to me, feel free to add:

Reviewed-by: Yu Kuai <yukuai3@huawei.com>
> 
> Signed-off-by: Zhong Jinghua <zhongjinghua@huawei.com>
> ---
>   drivers/block/nbd.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
> index 592cfa8b765a..e1c954094b6c 100644
> --- a/drivers/block/nbd.c
> +++ b/drivers/block/nbd.c
> @@ -325,6 +325,9 @@ static int nbd_set_size(struct nbd_device *nbd, loff_t bytesize,
>   	if (blk_validate_block_size(blksize))
>   		return -EINVAL;
>   
> +	if (bytesize < 0)
> +		return -EINVAL;
> +
>   	nbd->config->bytesize = bytesize;
>   	nbd->config->blksize_bits = __ffs(blksize);
>   
> @@ -1111,6 +1114,9 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
>   	struct nbd_sock *nsock;
>   	int err;
>   
> +	/* Arg will be cast to int, check it to avoid overflow */
> +	if (arg > INT_MAX)
> +		return -EINVAL;
>   	sock = nbd_get_socket(nbd, arg, &err);
>   	if (!sock)
>   		return err;
> 

Re: [PATCH-next] nbd: fix incomplete validation of ioctl arg

[Josef Bacik]

On Mon, Feb 06, 2023 at 10:58:05PM +0800, Zhong Jinghua wrote:
> We tested and found an alarm caused by nbd_ioctl arg without verification.
> The UBSAN warning calltrace like below:
> 
> UBSAN: Undefined behaviour in fs/buffer.c:1709:35
> signed integer overflow:
> -9223372036854775808 - 1 cannot be represented in type 'long long int'
> CPU: 3 PID: 2523 Comm: syz-executor.0 Not tainted 4.19.90 #1
> Hardware name: linux,dummy-virt (DT)
> Call trace:
>  dump_backtrace+0x0/0x3f0 arch/arm64/kernel/time.c:78
>  show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x170/0x1dc lib/dump_stack.c:118
>  ubsan_epilogue+0x18/0xb4 lib/ubsan.c:161
>  handle_overflow+0x188/0x1dc lib/ubsan.c:192
>  __ubsan_handle_sub_overflow+0x34/0x44 lib/ubsan.c:206
>  __block_write_full_page+0x94c/0xa20 fs/buffer.c:1709
>  block_write_full_page+0x1f0/0x280 fs/buffer.c:2934
>  blkdev_writepage+0x34/0x40 fs/block_dev.c:607
>  __writepage+0x68/0xe8 mm/page-writeback.c:2305
>  write_cache_pages+0x44c/0xc70 mm/page-writeback.c:2240
>  generic_writepages+0xdc/0x148 mm/page-writeback.c:2329
>  blkdev_writepages+0x2c/0x38 fs/block_dev.c:2114
>  do_writepages+0xd4/0x250 mm/page-writeback.c:2344
> 
> The reason for triggering this warning is __block_write_full_page()
> -> i_size_read(inode) - 1 overflow.
> inode->i_size is assigned in __nbd_ioctl() -> nbd_set_size() -> bytesize.
> We think it is necessary to limit the size of arg to prevent errors.
> 
> Moreover, __nbd_ioctl() -> nbd_add_socket(), arg will be cast to int.
> Assuming the value of arg is 0x80000000000000001) (on a 64-bit machine),
> it will become 1 after the coercion, which will return unexpected results.
> 
> Fix it by adding checks to prevent passing in too large numbers.
> 
> Signed-off-by: Zhong Jinghua <zhongjinghua@huawei.com>

Reviewed-by: Josef Bacik <josef@toxicpanda.com>

Thanks,

Josef

Re: [PATCH-next] nbd: fix incomplete validation of ioctl arg

[Jens Axboe]

On Mon, 06 Feb 2023 22:58:05 +0800, Zhong Jinghua wrote:
> We tested and found an alarm caused by nbd_ioctl arg without verification.
> The UBSAN warning calltrace like below:
> 
> UBSAN: Undefined behaviour in fs/buffer.c:1709:35
> signed integer overflow:
> -9223372036854775808 - 1 cannot be represented in type 'long long int'
> CPU: 3 PID: 2523 Comm: syz-executor.0 Not tainted 4.19.90 #1
> Hardware name: linux,dummy-virt (DT)
> Call trace:
>  dump_backtrace+0x0/0x3f0 arch/arm64/kernel/time.c:78
>  show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x170/0x1dc lib/dump_stack.c:118
>  ubsan_epilogue+0x18/0xb4 lib/ubsan.c:161
>  handle_overflow+0x188/0x1dc lib/ubsan.c:192
>  __ubsan_handle_sub_overflow+0x34/0x44 lib/ubsan.c:206
>  __block_write_full_page+0x94c/0xa20 fs/buffer.c:1709
>  block_write_full_page+0x1f0/0x280 fs/buffer.c:2934
>  blkdev_writepage+0x34/0x40 fs/block_dev.c:607
>  __writepage+0x68/0xe8 mm/page-writeback.c:2305
>  write_cache_pages+0x44c/0xc70 mm/page-writeback.c:2240
>  generic_writepages+0xdc/0x148 mm/page-writeback.c:2329
>  blkdev_writepages+0x2c/0x38 fs/block_dev.c:2114
>  do_writepages+0xd4/0x250 mm/page-writeback.c:2344
> 
> [...]

Applied, thanks!

[1/1] nbd: fix incomplete validation of ioctl arg
      commit: 55793ea54d77719a071b1ccc05a05056e3b5e009

Best regards,
-- 
Jens Axboe