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
-
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