From: Carlos Sanchez carlossanchez@geotab.com
Allows slcan to receive short messages (typically errors) from the serial interface.
When error support was added to slcan protocol in b32ff4668544e1333b694fcc7812b2d7397b4d6a ("can: slcan: extend the protocol with error info") the minimum valid message size changed from 5 (minimum standard can frame tIII0) to 3 ("e1a" is a valid protocol message, it is one of the examples given in the comments for slcan_bump_err() ), but the check for minimum message length prodicating all decoding was not adjusted. This makes short error messages discarded and error frames not being generated.
This patch changes the minimum length to the new minimum (3 characters, excluding terminator, is now a valid message).
Signed-off-by: Carlos Sanchez carlossanchez@geotab.com Fixes: b32ff4668544 ("can: slcan: extend the protocol with error info") Reviewed-by: Vincent Mailhol mailhol.vincent@wanadoo.fr Link: https://patch.msgid.link/20250520102305.1097494-1-carlossanchez@geotab.com Cc: stable@vger.kernel.org Signed-off-by: Marc Kleine-Budde mkl@pengutronix.de --- drivers/net/can/slcan/slcan-core.c | 26 ++++++++++++++++++++------ 1 file changed, 20 insertions(+), 6 deletions(-)
diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c index 24c6622d36bd..58ff2ec1d975 100644 --- a/drivers/net/can/slcan/slcan-core.c +++ b/drivers/net/can/slcan/slcan-core.c @@ -71,12 +71,21 @@ MODULE_AUTHOR("Dario Binacchi dario.binacchi@amarulasolutions.com"); #define SLCAN_CMD_LEN 1 #define SLCAN_SFF_ID_LEN 3 #define SLCAN_EFF_ID_LEN 8 +#define SLCAN_DATA_LENGTH_LEN 1 +#define SLCAN_ERROR_LEN 1 #define SLCAN_STATE_LEN 1 #define SLCAN_STATE_BE_RXCNT_LEN 3 #define SLCAN_STATE_BE_TXCNT_LEN 3 -#define SLCAN_STATE_FRAME_LEN (1 + SLCAN_CMD_LEN + \ - SLCAN_STATE_BE_RXCNT_LEN + \ - SLCAN_STATE_BE_TXCNT_LEN) +#define SLCAN_STATE_MSG_LEN (SLCAN_CMD_LEN + \ + SLCAN_STATE_LEN + \ + SLCAN_STATE_BE_RXCNT_LEN + \ + SLCAN_STATE_BE_TXCNT_LEN) +#define SLCAN_ERROR_MSG_LEN_MIN (SLCAN_CMD_LEN + \ + SLCAN_ERROR_LEN + \ + SLCAN_DATA_LENGTH_LEN) +#define SLCAN_FRAME_MSG_LEN_MIN (SLCAN_CMD_LEN + \ + SLCAN_SFF_ID_LEN + \ + SLCAN_DATA_LENGTH_LEN) struct slcan { struct can_priv can;
@@ -176,6 +185,9 @@ static void slcan_bump_frame(struct slcan *sl) u32 tmpid; char *cmd = sl->rbuff;
+ if (sl->rcount < SLCAN_FRAME_MSG_LEN_MIN) + return; + skb = alloc_can_skb(sl->dev, &cf); if (unlikely(!skb)) { sl->dev->stats.rx_dropped++; @@ -281,7 +293,7 @@ static void slcan_bump_state(struct slcan *sl) return; }
- if (state == sl->can.state || sl->rcount < SLCAN_STATE_FRAME_LEN) + if (state == sl->can.state || sl->rcount != SLCAN_STATE_MSG_LEN) return;
cmd += SLCAN_STATE_BE_RXCNT_LEN + SLCAN_CMD_LEN + 1; @@ -328,6 +340,9 @@ static void slcan_bump_err(struct slcan *sl) bool rx_errors = false, tx_errors = false, rx_over_errors = false; int i, len;
+ if (sl->rcount < SLCAN_ERROR_MSG_LEN_MIN) + return; + /* get len from sanitized ASCII value */ len = cmd[1]; if (len >= '0' && len < '9') @@ -456,8 +471,7 @@ static void slcan_bump(struct slcan *sl) static void slcan_unesc(struct slcan *sl, unsigned char s) { if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */ - if (!test_and_clear_bit(SLF_ERROR, &sl->flags) && - sl->rcount > 4) + if (!test_and_clear_bit(SLF_ERROR, &sl->flags)) slcan_bump(sl);
sl->rcount = 0;