Re: [PATCH v2] drivers/base: Fix length checks in create_syslog_header()/dev_vprintk_emit()

From: Greg Kroah-Hartman
Date: Wed Jul 09 2014 - 19:53:16 EST

On Sun, Jun 08, 2014 at 11:51:43PM +0100, Ben Hutchings wrote:
> snprintf() returns the number of bytes that could have been written
> (excluding the null), not the actual number of bytes written. Given a
> long enough subsystem or device name, these functions will advance
> beyond the end of the on-stack buffer in dev_vprintk_exit(), resulting
> in an information leak or stack corruption. I don't know whether such
> a long name is currently possible.
> In case snprintf() returns a value >= the buffer size, do not add
> structured logging information. Also WARN if this happens, so we can
> fix the driver or increase the buffer size.
> Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
> ---
> v2: use dev_WARN() not dev_WARN_ON()

This patch breaks the build in a huge way:

drivers/base/core.c: In function âcreate_syslog_headerâ:
drivers/base/core.c:2049:16: error: expected â)â before numeric constant
dev_WARN(dev, 1, "device/subsystem name too long");

is the start of it, it goes on for a page or so after that :(

greg k-h
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