Hello.
On pátek 28. července 2023 17:23:25 CEST David Laight wrote:
> From: Oleksandr Natalenko
> > Sent: 28 July 2023 07:58
> >
> > The qedf_dbg_stop_io_on_error_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.")
> ...
> > diff --git a/drivers/scsi/qedf/qedf_debugfs.c b/drivers/scsi/qedf/qedf_debugfs.c
> > index a3ed681c8ce3f..4d1b99569d490 100644
> > --- a/drivers/scsi/qedf/qedf_debugfs.c
> > +++ b/drivers/scsi/qedf/qedf_debugfs.c
> > @@ -185,18 +185,17 @@ qedf_dbg_stop_io_on_error_cmd_read(struct file *filp, char __user *buffer,
> > size_t count, loff_t *ppos)
> > {
> > int cnt;
> > + char cbuf[7];
> > struct qedf_dbg_ctx *qedf_dbg =
> > (struct qedf_dbg_ctx *)filp->private_data;
> > struct qedf_ctx *qedf = container_of(qedf_dbg,
> > struct qedf_ctx, dbg_ctx);
> >
> > QEDF_INFO(qedf_dbg, QEDF_LOG_DEBUGFS, "entered\n");
> > - cnt = sprintf(buffer, "%s\n",
> > + cnt = sprintf(cbuf, "%s\n",
> > qedf->stop_io_on_error ? "true" : "false");
>
> You've made cbuf[] exactly just big enough.
> If anyone breathes on this code it could overflow.
> You really should use scnprintf() for safety.
OK, I'll do scnprintf(cbuf, sizeof(cbuf), ...) in the next version of the submission.
Thanks.
> >
> > - cnt = min_t(int, count, cnt - *ppos);
> > - *ppos += cnt;
> > - return cnt;
> > + return simple_read_from_buffer(buffer, count, ppos, cbuf, cnt);
>
> Or just:
> if (gedf->stop_on_error)
> return simple_read_from_buffer(buffer, count, ppos, "true\n", 5);
> return simple_read_from_buffer(buffer, count, ppos, "false\n", 6);
>
> David
>
>
> > }
> >
> > static ssize_t
> > --
> > 2.41.0
>
> -
> Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
> Registration No: 1397386 (Wales)
>
>
--
Oleksandr Natalenko (post-factum)
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