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| author | Francois-Xavier Le Bail <devel.fx.lebail@orange.fr> | 2019-03-28 13:44:50 +0100 |
|---|---|---|
| committer | Francois-Xavier Le Bail <devel.fx.lebail@orange.fr> | 2019-03-28 14:13:27 +0100 |
| commit | 400643120a48eca33973f6a47b34f0dcfde4d20a (patch) | |
| tree | 1b13f95a009e86c6e4fbb3249f03177e0b83b508 /print-802_15_4.c | |
| parent | f280b3c0dfb5200512ebb03b1e9b7e2ab868dd5b (diff) | |
| download | tcpdump-400643120a48eca33973f6a47b34f0dcfde4d20a.tar.gz | |
IEEE 802.15.4: Fix an undefined behavior at runtime
The error was:
print-802_15_4.c:442:9: runtime error: implicit conversion from type
'int' of value 15840046 (32-bit, signed) to type 'uint16_t' (aka
'unsigned short') changed the value to 45870 (16-bit, unsigned)
Proposal of fix by Guy Harris:
"Those shifted values will be converted (in the C abstract machine) to
int, but they'll all be in the range 0 to 65535, as will be the XOR of
all 4 of them; converting that to a uint16_t isn't undefined behavior."
Diffstat (limited to 'print-802_15_4.c')
| -rw-r--r-- | print-802_15_4.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/print-802_15_4.c b/print-802_15_4.c index 54279cca..b1800e08 100644 --- a/print-802_15_4.c +++ b/print-802_15_4.c @@ -439,10 +439,10 @@ ieee802_15_4_crc16(const u_char *p, /* Update CRC */ x = crc >> 8 ^ y; x ^= x >> 4; - crc = (crc << 8) ^ - ((unsigned short)(x << 12)) ^ - ((unsigned short)(x <<5)) ^ - ((unsigned short)x); + crc = ((uint16_t)(crc << 8)) ^ + ((uint16_t)(x << 12)) ^ + ((uint16_t)(x << 5)) ^ + ((uint16_t)x); data_len--; } /* Reverse bits on output */ |