2023-02-21 09:27:20

by zhongjinghua

Subject: [PATCH-next v4] loop: loop_set_status_from_info() check before assignment

From: Zhong Jinghua <[email protected]>

In loop_set_status_from_info(), lo->lo_offset and lo->lo_sizelimit should
be checked before reassignment, because if an overflow error occurs, the
original correct value will be changed to the wrong value, and it will not
be changed back.

More, the original patch did not solve the problem, the value was set and
ioctl returned an error, but the subsequent io used the value in the loop
driver, which still caused an alarm:

loop_handle_cmd
do_req_filebacked
loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
lo_rw_aio
cmd->iocb.ki_pos = pos

Fixes: c490a0b5a4f3 ("loop: Check for overflow while configuring loop")
Signed-off-by: Zhong Jinghua <[email protected]>
---
v2: Modify note: overflowing -> overflow
v3: Modify commit message
v4: Modify commit message
drivers/block/loop.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 1518a6423279..1b35cbd029c7 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -977,13 +977,13 @@ loop_set_status_from_info(struct loop_device *lo,
return -EINVAL;
}

+ /* Avoid assigning overflow values */
+ if (info->lo_offset > LLONG_MAX || info->lo_sizelimit > LLONG_MAX)
+ return -EOVERFLOW;
+
lo->lo_offset = info->lo_offset;
lo->lo_sizelimit = info->lo_sizelimit;

- /* loff_t vars have been assigned __u64 */
- if (lo->lo_offset < 0 || lo->lo_sizelimit < 0)
- return -EOVERFLOW;
-
memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
lo->lo_file_name[LO_NAME_SIZE-1] = 0;
lo->lo_flags = info->lo_flags;
--
2.31.1

2023-02-21 18:00:04

by Chaitanya Kulkarni

Subject: Re: [PATCH-next v4] loop: loop_set_status_from_info() check before assignment

On 2/21/2023 1:50 AM, Zhong Jinghua wrote:
> From: Zhong Jinghua <[email protected]>
>
> In loop_set_status_from_info(), lo->lo_offset and lo->lo_sizelimit should
> be checked before reassignment, because if an overflow error occurs, the
> original correct value will be changed to the wrong value, and it will not
> be changed back.
>
> More, the original patch did not solve the problem, the value was set and
> ioctl returned an error, but the subsequent io used the value in the loop
> driver, which still caused an alarm:
>
> loop_handle_cmd
> do_req_filebacked
> loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
> lo_rw_aio
> cmd->iocb.ki_pos = pos
>
> Fixes: c490a0b5a4f3 ("loop: Check for overflow while configuring loop")
> Signed-off-by: Zhong Jinghua <[email protected]>


Reviewed-by: Chaitanya Kulkarni <[email protected]>

-ck

2023-02-23 03:43:47

by Jens Axboe

Subject: Re: [PATCH-next v4] loop: loop_set_status_from_info() check before assignment

On Tue, 21 Feb 2023 17:50:27 +0800, Zhong Jinghua wrote:
> In loop_set_status_from_info(), lo->lo_offset and lo->lo_sizelimit should
> be checked before reassignment, because if an overflow error occurs, the
> original correct value will be changed to the wrong value, and it will not
> be changed back.
>
> More, the original patch did not solve the problem, the value was set and
> ioctl returned an error, but the subsequent io used the value in the loop
> driver, which still caused an alarm:
>
> [...]

Applied, thanks!

[1/1] loop: loop_set_status_from_info() check before assignment
commit: 9f6ad5d533d1c71e51bdd06a5712c4fbc8768dfa

Best regards,
--
Jens Axboe