drivers/base: Fix length checks in create_syslog_header()/dev_vprintk_emit()
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@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 file changed