| Message ID | 20230728065819.139694-3-oleksandr@redhat.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | scsi: qedf: sanitise uaccess | expand |
From: Oleksandr Natalenko > Sent: 28 July 2023 07:58 > > The qedf_dbg_debug_cmd_read() function invokes sprintf() > directly on a __user pointer, which may crash the kernel. ^^^ will > > Avoid doing that by using a small on-stack buffer for sprintf() > and then calling simple_read_from_buffer() which does a proper > copy_to_user() call. ... > diff --git a/drivers/scsi/qedf/qedf_debugfs.c b/drivers/scsi/qedf/qedf_debugfs.c > index 4d1b99569d490..f910af0029a2c 100644 > --- a/drivers/scsi/qedf/qedf_debugfs.c > +++ b/drivers/scsi/qedf/qedf_debugfs.c > @@ -138,15 +138,14 @@ qedf_dbg_debug_cmd_read(struct file *filp, char __user *buffer, size_t count, > loff_t *ppos) > { > int cnt; > + char cbuf[35]; Why 35? I pick a multiple of 8 that if 'enough. > struct qedf_dbg_ctx *qedf_dbg = > (struct qedf_dbg_ctx *)filp->private_data; > > QEDF_INFO(qedf_dbg, QEDF_LOG_DEBUGFS, "debug mask=0x%x\n", qedf_debug); > - cnt = sprintf(buffer, "debug mask = 0x%x\n", qedf_debug); > + cnt = sprintf(cbuf, "debug mask = 0x%x\n", qedf_debug); Use scnprintf() to be sure it doesn't overflow. Much safer if someone does a quick update or copies the code. David > > - cnt = min_t(int, count, cnt - *ppos); > - *ppos += cnt; > - return cnt; > + return simple_read_from_buffer(buffer, count, ppos, cbuf, cnt); > } > > static ssize_t > -- > 2.41.0 - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
Hello/ On pátek 28. července 2023 17:26:11 CEST David Laight wrote: > From: Oleksandr Natalenko > > Sent: 28 July 2023 07:58 > > > > The qedf_dbg_debug_cmd_read() function invokes sprintf() > > directly on a __user pointer, which may crash the kernel. > ^^^ will I don't think it is 100% guaranteed, but for sure this is not a correct behaviour. > > > > Avoid doing that by using a small on-stack buffer for sprintf() > > and then calling simple_read_from_buffer() which does a proper > > copy_to_user() call. > ... > > diff --git a/drivers/scsi/qedf/qedf_debugfs.c b/drivers/scsi/qedf/qedf_debugfs.c > > index 4d1b99569d490..f910af0029a2c 100644 > > --- a/drivers/scsi/qedf/qedf_debugfs.c > > +++ b/drivers/scsi/qedf/qedf_debugfs.c > > @@ -138,15 +138,14 @@ qedf_dbg_debug_cmd_read(struct file *filp, char __user *buffer, size_t count, > > loff_t *ppos) > > { > > int cnt; > > + char cbuf[35]; > > Why 35? > I pick a multiple of 8 that if 'enough. OK, I overestimated this, it should have been 27, but I'll make it 32 to be a multiple of 8. Thanks. > > struct qedf_dbg_ctx *qedf_dbg = > > (struct qedf_dbg_ctx *)filp->private_data; > > > > QEDF_INFO(qedf_dbg, QEDF_LOG_DEBUGFS, "debug mask=0x%x\n", qedf_debug); > > - cnt = sprintf(buffer, "debug mask = 0x%x\n", qedf_debug); > > + cnt = sprintf(cbuf, "debug mask = 0x%x\n", qedf_debug); > > Use scnprintf() to be sure it doesn't overflow. > Much safer if someone does a quick update or copies the code. > > David > > > > > - cnt = min_t(int, count, cnt - *ppos); > > - *ppos += cnt; > > - return cnt; > > + return simple_read_from_buffer(buffer, count, ppos, cbuf, cnt); > > } > > > > static ssize_t > > -- > > 2.41.0 > > - > Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK > Registration No: 1397386 (Wales) > >
diff --git a/drivers/scsi/qedf/qedf_debugfs.c b/drivers/scsi/qedf/qedf_debugfs.c index 4d1b99569d490..f910af0029a2c 100644 --- a/drivers/scsi/qedf/qedf_debugfs.c +++ b/drivers/scsi/qedf/qedf_debugfs.c @@ -138,15 +138,14 @@ qedf_dbg_debug_cmd_read(struct file *filp, char __user *buffer, size_t count, loff_t *ppos) { int cnt; + char cbuf[35]; struct qedf_dbg_ctx *qedf_dbg = (struct qedf_dbg_ctx *)filp->private_data; QEDF_INFO(qedf_dbg, QEDF_LOG_DEBUGFS, "debug mask=0x%x\n", qedf_debug); - cnt = sprintf(buffer, "debug mask = 0x%x\n", qedf_debug); + cnt = sprintf(cbuf, "debug mask = 0x%x\n", qedf_debug); - cnt = min_t(int, count, cnt - *ppos); - *ppos += cnt; - return cnt; + return simple_read_from_buffer(buffer, count, ppos, cbuf, cnt); } static ssize_t
The qedf_dbg_debug_cmd_read() function invokes sprintf() directly on a __user pointer, which may crash the kernel. Avoid doing that by using a small on-stack buffer for sprintf() and then calling simple_read_from_buffer() which does a proper copy_to_user() call. Fixes: 61d8658b4a ("scsi: qedf: Add QLogic FastLinQ offload FCoE driver framework.") Link: https://lore.kernel.org/lkml/20230724120241.40495-1-oleksandr@redhat.com/ Link: https://lore.kernel.org/linux-scsi/20230726101236.11922-1-skashyap@marvell.com/ Cc: Saurav Kashyap <skashyap@marvell.com> Cc: Rob Evers <revers@redhat.com> Cc: Johannes Thumshirn <Johannes.Thumshirn@wdc.com> Cc: Jozef Bacik <jobacik@redhat.com> Cc: Laurence Oberman <loberman@redhat.com> Cc: "James E.J. Bottomley" <jejb@linux.ibm.com> Cc: "Martin K. Petersen" <martin.petersen@oracle.com> Cc: GR-QLogic-Storage-Upstream@marvell.com Cc: linux-scsi@vger.kernel.org Tested-by: Laurence Oberman <loberman@redhat.com> Signed-off-by: Oleksandr Natalenko <oleksandr@redhat.com> --- drivers/scsi/qedf/qedf_debugfs.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)