Author: ian
Date: Sun Dec 31 22:43:24 2017
New Revision: 327453
URL: https://svnweb.freebsd.org/changeset/base/327453
Log:
Add a validbcd() routine that uses the bcd2bin_data[] array and returns a
bool indicating whether the input value represents a valid BCD byte.
The existing bcd2bin() routine will KASSERT if asked to convert a bad value,
but sometimes the kernel has to handle BCD data from untrusted sources, so
this will provide a mechanism to validate data before attempting conversion.
This would be have easier/cleaner if the bcd2bin_data[] array contained an
out-of-range value (such as 0xff) in the infill locations that aren't valid,
but it's a global symbol that might be referenced by out-of-tree code
relying on the current scheme, so I'm leaving that alone.
Modified:
head/stand/libsa/stand.h
head/sys/sys/libkern.h
Modified: head/stand/libsa/stand.h
==============================================================================
--- head/stand/libsa/stand.h Sun Dec 31 22:35:32 2017 (r327452)
+++ head/stand/libsa/stand.h Sun Dec 31 22:43:24 2017 (r327453)
@@ -354,6 +354,7 @@ extern char const hex2ascii_data[];
#define bcd2bin(bcd) (bcd2bin_data[bcd])
#define bin2bcd(bin) (bin2bcd_data[bin])
#define hex2ascii(hex) (hex2ascii_data[hex])
+#define validbcd(bcd) (bcd == 0 || (bcd > 0 && bcd <= 0x99 &&
bcd2bin_data[bcd] != 0))
/* min/max (undocumented) */
static __inline int imax(int a, int b) { return (a > b ? a : b); }
Modified: head/sys/sys/libkern.h
==============================================================================
--- head/sys/sys/libkern.h Sun Dec 31 22:35:32 2017 (r327452)
+++ head/sys/sys/libkern.h Sun Dec 31 22:43:24 2017 (r327453)
@@ -82,6 +82,13 @@ hex2ascii(int hex)
return (hex2ascii_data[hex]);
}
+static inline bool
+validbcd(int bcd)
+{
+
+ return (bcd == 0 || (bcd > 0 && bcd <= 0x99 && bcd2bin_data[bcd] != 0));
+}
+
static __inline int imax(int a, int b) { return (a > b ? a : b); }
static __inline int imin(int a, int b) { return (a < b ? a : b); }
static __inline long lmax(long a, long b) { return (a > b ? a : b); }
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