drivers/base: Fix length checks in create_syslog_header()/dev_vprintk_emit()
authorBen Hutchings <ben@decadent.org.uk>
Tue, 26 Aug 2014 07:34:44 +0000 (00:34 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 24 Sep 2014 05:55:15 +0000 (22:55 -0700)
commit655e5b7c031e84cf8c07cfd6a5944ce53cba1add
treed99c06b802df92b1618fe67fe3a6a5e811b7b43b
parent833c95456a70826d1384883b73fd23aff24d366f
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>
drivers/base/core.c