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>
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@ -2007,6 +2007,8 @@ create_syslog_header(const struct device *dev, char *hdr, size_t hdrlen)
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return 0;
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return 0;
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pos += snprintf(hdr + pos, hdrlen - pos, "SUBSYSTEM=%s", subsys);
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pos += snprintf(hdr + pos, hdrlen - pos, "SUBSYSTEM=%s", subsys);
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if (pos >= hdrlen)
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goto overflow;
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/*
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/*
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* Add device identifier DEVICE=:
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* Add device identifier DEVICE=:
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@ -2038,7 +2040,14 @@ create_syslog_header(const struct device *dev, char *hdr, size_t hdrlen)
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"DEVICE=+%s:%s", subsys, dev_name(dev));
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"DEVICE=+%s:%s", subsys, dev_name(dev));
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}
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}
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if (pos >= hdrlen)
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goto overflow;
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return pos;
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return pos;
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overflow:
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dev_WARN(dev, "device/subsystem name too long");
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return 0;
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}
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}
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int dev_vprintk_emit(int level, const struct device *dev,
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int dev_vprintk_emit(int level, const struct device *dev,
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