Messages in this thread Patch in this message |  | | | Subject | [PATCH] Add error check to hex2bin(). | | From | Tetsuo Handa <> | | Date | Mon, 18 Jul 2011 21:48:32 +0900 |
| |
Currently, security/keys/ is the only user of hex2bin(). Should I keep hex2bin() unmodified in case of bad input? If so, I'd like to make it as hex2bin_safe(). ---------------------------------------- [PATCH] Add error check to hex2bin(). Since converting 2 hexadecimal letters into a byte with error checks is commonly used, we can replace multiple hex_to_bin() calls with single hex2bin() call by changing hex2bin() to do error checks.
Signed-off-by: Tetsuo Handa <penguin-kernel@I=love.SAKURA.ne.jp> --- diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 953352a..186e9fc 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -374,7 +374,7 @@ static inline char *pack_hex_byte(char *buf, u8 byte) } extern int hex_to_bin(char ch); -extern void hex2bin(u8 *dst, const char *src, size_t count); +extern bool hex2bin(u8 *dst, const char *src, size_t count); /* * General tracing related utility functions - trace_printk(), diff --git a/lib/hexdump.c b/lib/hexdump.c index f5fe6ba..1524002 100644 --- a/lib/hexdump.c +++ b/lib/hexdump.c @@ -38,14 +38,22 @@ EXPORT_SYMBOL(hex_to_bin); * @dst: binary result * @src: ascii hexadecimal string * @count: result length + * + * Returns true on success, false in case of bad input. */ -void hex2bin(u8 *dst, const char *src, size_t count) +bool hex2bin(u8 *dst, const char *src, size_t count) { while (count--) { - *dst = hex_to_bin(*src++) << 4; - *dst += hex_to_bin(*src++); - dst++; + int c = hex_to_bin(*src++); + int d; + if (c < 0) + return false; + d = hex_to_bin(*src++); + if (d < 0) + return false; + *dst++ = (c << 4) | d; } + return true; } EXPORT_SYMBOL(hex2bin);
In message "Re: [PATCH] net: can: remove custom hex_to_bin()", Andy Shevchenko wrote: > On Mon, 2011-07-18 at 20:41 +0900, Tetsuo Handa wrote: > > Andy Shevchenko wrote: > > > for (i = 0, dlc_pos++; i < cf.can_dlc; i++) { > > > - > > > - tmp = asc2nibble(sl->rbuff[dlc_pos++]); > > > - if (tmp > 0x0F) > > > + tmp = hex_to_bin(sl->rbuff[dlc_pos++]); > > > + if (tmp < 0) > > > return; > > > cf.data[i] = (tmp << 4); > > > - tmp = asc2nibble(sl->rbuff[dlc_pos++]); > > > - if (tmp > 0x0F) > > > + tmp = hex_to_bin(sl->rbuff[dlc_pos++]); > > > + if (tmp < 0) > > > return; > > > cf.data[i] |= tmp; > > > } > > > > What about changing > > > > void hex2bin(u8 *dst, const char *src, size_t count) > > > > to > > > > bool hex2bin(u8 *dst, const char *src, size_t count) > > > > in order to do error checks like > > > > bool hex2bin_with_validation(u8 *dst, const char *src, size_t count) > > { > > while (count--) { > > int c = hex_to_bin(*src++); > > int d; > > if (c < 0) > > return false; > > d = hex_to_bin(*src++) > > if (d < 0) > > return false; > > *dst++ = (c << 4) | d; > > } > > return true; > > } > > > > and use hex2bin() rather than hex_to_bin()? > Perhaps, good idea. Could you submit a patch? > > -- > Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Intel Finland Oy
|  |