From 655e5b7c031e84cf8c07cfd6a5944ce53cba1add Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Tue, 26 Aug 2014 00:34:44 -0700 Subject: [PATCH] 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 Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/base/core.c b/drivers/base/core.c index 20da3ad1696b..28b808c73e8e 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -2007,6 +2007,8 @@ create_syslog_header(const struct device *dev, char *hdr, size_t hdrlen) return 0; pos += snprintf(hdr + pos, hdrlen - pos, "SUBSYSTEM=%s", subsys); + if (pos >= hdrlen) + goto overflow; /* * Add device identifier DEVICE=: @@ -2038,7 +2040,14 @@ create_syslog_header(const struct device *dev, char *hdr, size_t hdrlen) "DEVICE=+%s:%s", subsys, dev_name(dev)); } + if (pos >= hdrlen) + goto overflow; + return pos; + +overflow: + dev_WARN(dev, "device/subsystem name too long"); + return 0; } int dev_vprintk_emit(int level, const struct device *dev, -- 2.20.1