diff options
| -rw-r--r-- | module/elmcan.c | 34 |
1 files changed, 16 insertions, 18 deletions
diff --git a/module/elmcan.c b/module/elmcan.c index 7bb2784..35f194e 100644 --- a/module/elmcan.c +++ b/module/elmcan.c @@ -316,23 +316,21 @@ static inline void elm327_hw_failure(struct elmcan *elm) elm327_feed_frame_to_netdev(elm, skb); } -/* Compare a buffer to a fixed string */ -static inline int _memstrcmp(const u8 *mem, const char *str) -{ - return memcmp(mem, str, strlen(str)); -} - /* Compare buffer to string length, then compare buffer to fixed string. * This ensures two things: * - It flags cases where the fixed string is only the start of the * buffer, rather than exactly all of it. * - It avoids byte comparisons in case the length doesn't match. + * + * strncmp() cannot be used here because it accepts the following wrong case: + * strncmp("CAN ER", "CAN ERROR", 6); + * This must fail, hence this helper function. */ -static inline int _len_memstrcmp(const u8 *mem, size_t mem_len, const char *str) +static inline int check_len_then_cmp(const u8 *mem, size_t mem_len, const char *str) { size_t str_len = strlen(str); - return (mem_len != str_len) || memcmp(mem, str, str_len); + return (mem_len == str_len) && !memcmp(mem, str, str_len); } static void elm327_parse_error(struct elmcan *elm, size_t len) @@ -350,29 +348,29 @@ static void elm327_parse_error(struct elmcan *elm, size_t len) return; /* Filter possible error messages based on length of RX'd line */ - if (!_len_memstrcmp(elm->rxbuf, len, "UNABLE TO CONNECT")) { + if (check_len_then_cmp(elm->rxbuf, len, "UNABLE TO CONNECT")) { netdev_err(elm->dev, "ELM327 reported UNABLE TO CONNECT. Please check your setup.\n"); - } else if (!_len_memstrcmp(elm->rxbuf, len, "BUFFER FULL")) { + } else if (check_len_then_cmp(elm->rxbuf, len, "BUFFER FULL")) { /* This will only happen if the last data line was complete. * Otherwise, elm327_parse_frame() will heuristically * emit this kind of error frame instead. */ frame->can_id |= CAN_ERR_CRTL; frame->data[1] = CAN_ERR_CRTL_RX_OVERFLOW; - } else if (!_len_memstrcmp(elm->rxbuf, len, "BUS ERROR")) { + } else if (check_len_then_cmp(elm->rxbuf, len, "BUS ERROR")) { frame->can_id |= CAN_ERR_BUSERROR; - } else if (!_len_memstrcmp(elm->rxbuf, len, "CAN ERROR")) { + } else if (check_len_then_cmp(elm->rxbuf, len, "CAN ERROR")) { frame->can_id |= CAN_ERR_PROT; - } else if (!_len_memstrcmp(elm->rxbuf, len, "<RX ERROR")) { + } else if (check_len_then_cmp(elm->rxbuf, len, "<RX ERROR")) { frame->can_id |= CAN_ERR_PROT; - } else if (!_len_memstrcmp(elm->rxbuf, len, "BUS BUSY")) { + } else if (check_len_then_cmp(elm->rxbuf, len, "BUS BUSY")) { frame->can_id |= CAN_ERR_PROT; frame->data[2] = CAN_ERR_PROT_OVERLOAD; - } else if (!_len_memstrcmp(elm->rxbuf, len, "FB ERROR")) { + } else if (check_len_then_cmp(elm->rxbuf, len, "FB ERROR")) { frame->can_id |= CAN_ERR_PROT; frame->data[2] = CAN_ERR_PROT_TX; - } else if (len == 5 && !_memstrcmp(elm->rxbuf, "ERR")) { + } else if (len == 5 && !memcmp(elm->rxbuf, "ERR", 3)) { /* ERR is followed by two digits, hence line length 5 */ netdev_err(elm->dev, "ELM327 reported an ERR%c%c. Please power it off and on again.\n", elm->rxbuf[3], elm->rxbuf[4]); @@ -489,7 +487,7 @@ static int elm327_parse_frame(struct elmcan *elm, size_t len) /* Check for RTR frame */ if (elm->rxfill >= hexlen + 3 && - !_memstrcmp(&elm->rxbuf[hexlen], "RTR")) { + !memcmp(&elm->rxbuf[hexlen], "RTR", 3)) { frame->can_id |= CAN_RTR_FLAG; } @@ -539,7 +537,7 @@ static void elm327_parse_line(struct elmcan *elm, size_t len) if (elm->drop_next_line) { elm->drop_next_line = 0; return; - } else if (!_memstrcmp(elm->rxbuf, "AT")) { + } else if (!memcmp(elm->rxbuf, "AT", 2)) { return; } |