linux-kernel - Re: [PATCH 0/3] scsi: qedf: sanitise uaccess

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Date:   Fri, 28 Jul 2023 09:05:07 +0200
From:   Oleksandr Natalenko <oleksandr@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-scsi@...r.kernel.org, Saurav Kashyap <skashyap@...vell.com>,
        Johannes Thumshirn <Johannes.Thumshirn@....com>,
        GR-QLogic-Storage-Upstream@...vell.com,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Jozef Bacik <jobacik@...hat.com>,
        Laurence Oberman <loberman@...hat.com>,
        Rob Evers <revers@...hat.com>
Subject: Re: [PATCH 0/3] scsi: qedf: sanitise uaccess

On pátek 28. července 2023 8:58:16 CEST Oleksandr Natalenko wrote:
> qedf driver, debugfs part of it specifically, touches __user pointers
> directly for printing out info to userspace via sprintf(), which may
> cause crash like this:
> 
> BUG: unable to handle kernel paging request at 00007ffd1d6b43a0
> IP: [<ffffffffaa7a882a>] string.isra.7+0x6a/0xf0
> Oops: 0003 [#1] SMP
> Call Trace:
>  [<ffffffffaa7a9f31>] vsnprintf+0x201/0x6a0
>  [<ffffffffaa7aa556>] sprintf+0x56/0x80
>  [<ffffffffc04227ed>] qedf_dbg_stop_io_on_error_cmd_read+0x6d/0x90 [qedf]
>  [<ffffffffaa65bb2f>] vfs_read+0x9f/0x170
>  [<ffffffffaa65cb82>] SyS_pread64+0x92/0xc0
> 
> Avoid this by preparing the info in a kernel buffer first, either
> allocated on stack for small printouts, or via vmalloc() for big ones,
> and then copying it to the userspace properly.
> 
> Previous submission is an RFC: [1]. There are no code changes since
> then. The RFC prefix is dropped. The Tested-by tag from Laurence is
> added.
> 
> There's similar submission from Saurav [2], but we agreed I could nack
> it and proceed with my one.
> 
> [1] https://lore.kernel.org/linux-scsi/20230724120241.40495-1-oleksandr@redhat.com/
> [2] https://lore.kernel.org/linux-scsi/20230726101236.11922-1-skashyap@marvell.com/
> 
> Oleksandr Natalenko (3):
>   scsi: qedf: do not touch __user pointer in
>     qedf_dbg_stop_io_on_error_cmd_read() directly
>   scsi: qedf: do not touch __user pointer in qedf_dbg_debug_cmd_read()
>     directly
>   scsi: qedf: do not touch __user pointer in qedf_dbg_fp_int_cmd_read()
>     directly
> 
>  drivers/scsi/qedf/qedf_dbg.h     |  2 ++
>  drivers/scsi/qedf/qedf_debugfs.c | 35 +++++++++++++++++++-------------
>  2 files changed, 23 insertions(+), 14 deletions(-)
> 
> 

Oops, I forgot to add:

Reviewed-by: Laurence Oberman <loberman@...hat.com>

as per [1].

My ask to the maintainer to add it if the submission is accepted, or let me know if I should do a v2 instead.

[1] https://lore.kernel.org/linux-scsi/4f35b02968a18e636e1689c9d52729ef63a438f9.camel@redhat.com/

-- 
Oleksandr Natalenko (post-factum)
Principal Software Maintenance Engineer
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