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can: rework the table lookup code in can_dlc_to_bytes

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Rework the can_dlc_to_bytes table lookup code in a way that allow the
compiler to guess the resulting output and somehow fix the build
warning:

zephyr/drivers/can/can_nxp_s32_canxl.c:757:9: warning:
'__builtin___memcpy_chk' forming offset [16, 71] is out of the bounds
[0, 16] of object 'frame' with type 'struct can_frame' [-Warray-bounds]
 757 | memcpy(frame->data, msg_data.data, can_dlc_to_bytes(frame->dlc));

where the compiler detects that frame->data is 8 bytes long but
can_dlc_to_bytes could return more than that.

Can be reproduced with:

west build -p -b s32z270dc2_rtu1_r52 \
	-T samples/net/sockets/can/sample.net.sockets.can.one_socket

Suggested-by: Martin Jäger <martin@libre.solar>
Signed-off-by: Fabio Baltieri <fabiobaltieri@google.com>
This commit is contained in:
Fabio Baltieri 2023-09-13 16:16:55 +00:00 • committed by Carles Cufí
commit 4856fd4cb6
1 changed files with 1 additions and 1 deletions
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2
include/zephyr/drivers/can.h
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@ -1360,7 +1360,7 @@ static inline uint8_t can_dlc_to_bytes(uint8_t dlc)
static const uint8_t dlc_table[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 12,
16, 20, 24, 32, 48, 64};
return dlc > 0x0F ? 64 : dlc_table[dlc];
return dlc_table[MIN(dlc, ARRAY_SIZE(dlc_table) - 1)];
}
/**