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

From: Joe Perches
Date: Sun Jun 08 2014 - 22:16:23 EST


On Sun, 2014-06-08 at 23:51 +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.

I believe this is guaranteed to be < 128, but
I also suppose it'd be better to emit whatever
buffer is < 128 and add a WARN_ON_ONCE instead.


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/