Messages in this thread Patch in this message | | | Subject | [PATCH v2] drivers/base: Fix length checks in create_syslog_header()/dev_vprintk_emit() | From | Ben Hutchings <> | Date | Sun, 08 Jun 2014 23:51:43 +0100 |
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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> --- v2: use dev_WARN() not dev_WARN_ON()
drivers/base/core.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/drivers/base/core.c b/drivers/base/core.c index 20da3ad..062b7bf 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, 1, "device/subsystem name too long"); + return 0; } int dev_vprintk_emit(int level, const struct device *dev, -- Ben Hutchings Never attribute to conspiracy what can adequately be explained by stupidity. [unhandled content-type:application/pgp-signature] | |