Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <a44acf6edf8714f9e247e8de371d0f00521ec6b5.camel@redhat.com>
Subject: Re: [PATCH v2 0/3] scsi: qedf: sanitise uaccess
From:   Laurence Oberman <loberman@redhat.com>
To:     Oleksandr Natalenko <oleksandr@redhat.com>,
        linux-kernel@vger.kernel.org
Cc:     linux-scsi@vger.kernel.org, Saurav Kashyap <skashyap@marvell.com>,
        Johannes Thumshirn <Johannes.Thumshirn@wdc.com>,
        David Laight <David.Laight@ACULAB.COM>,
        GR-QLogic-Storage-Upstream@marvell.com,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Jozef Bacik <jobacik@redhat.com>, Rob Evers <revers@redhat.com>
Date:   Mon, 31 Jul 2023 14:33:28 -0400
In-Reply-To: <20230731084034.37021-1-oleksandr@redhat.com>
References: <20230731084034.37021-1-oleksandr@redhat.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
User-Agent: Evolution 3.46.4 (3.46.4-1.fc37) 
MIME-Version: 1.0
Precedence: bulk

On Mon, 2023-07-31 at 10:40 +0200, 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:
>=20
> BUG: unable to handle kernel paging request at 00007ffd1d6b43a0
> IP: [<ffffffffaa7a882a>] string.isra.7+0x6a/0xf0
> Oops: 0003 [#1] SMP
> Call Trace:
> =C2=A0[<ffffffffaa7a9f31>] vsnprintf+0x201/0x6a0
> =C2=A0[<ffffffffaa7aa556>] sprintf+0x56/0x80
> =C2=A0[<ffffffffc04227ed>] qedf_dbg_stop_io_on_error_cmd_read+0x6d/0x90
> [qedf]
> =C2=A0[<ffffffffaa65bb2f>] vfs_read+0x9f/0x170
> =C2=A0[<ffffffffaa65cb82>] SyS_pread64+0x92/0xc0
>=20
> 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.
>=20
> Changes since v1 [1]:
>=20
> =C2=A0 * use scnprintf() for on-stack buffers too
> =C2=A0 * adjust an on-stack buffer size in qedf_dbg_debug_cmd_read() to b=
e
> a
> =C2=A0=C2=A0=C2=A0 multiple of 8, and also size it properly
> =C2=A0 * accumulate acks and reviews
>=20
> [1]
> https://lore.kernel.org/lkml/20230728065819.139694-1-oleksandr@redhat.com=
/
>=20
> Oleksandr Natalenko (3):
> =C2=A0 scsi: qedf: do not touch __user pointer in
> =C2=A0=C2=A0=C2=A0 qedf_dbg_stop_io_on_error_cmd_read() directly
> =C2=A0 scsi: qedf: do not touch __user pointer in
> qedf_dbg_debug_cmd_read()
> =C2=A0=C2=A0=C2=A0 directly
> =C2=A0 scsi: qedf: do not touch __user pointer in
> qedf_dbg_fp_int_cmd_read()
> =C2=A0=C2=A0=C2=A0 directly
>=20
> =C2=A0drivers/scsi/qedf/qedf_dbg.h=C2=A0=C2=A0=C2=A0=C2=A0 |=C2=A0 2 ++
> =C2=A0drivers/scsi/qedf/qedf_debugfs.c | 35 +++++++++++++++++++----------=
-
> --
> =C2=A02 files changed, 23 insertions(+), 14 deletions(-)
>=20
In case it's needed

For the series v2 against 6.5-rc3
Reviewed-by: Laurence Oberman <loberman@redhat.com>
Tested-by: Laurence Oberman <loberman@redhat.com>

Test notes

Linux segstorage5 6.5.0-rc3+

[root@segstorage5 qedf]# cd host2
[root@segstorage5 host2]# ls
clear_stats  debug  driver_stats  fp_int  io_trace  offload_stats=20
stop_io_on_error

[root@segstorage5 host2]# cat stop_io_on_error
false

[root@segstorage5 host2]# cat fp_int

Fastpath I/O completions

#0: 844
#1: 990
#2: 1036
#3: 1116
#4: 953
#5: 822
#6: 882
#7: 1073
#8: 1030
#9: 992
#10: 789
#11: 705
#12: 490
#13: 532
#14: 646
#15: 705

[root@segstorage5 host2]# cat debug
debug mask =3D 0x2