Hi people, thanks for the additional information here. > > Sorry for later response due to leave home today. acpi_gsb_i2c_read_bytes() > > dedicates for GenericSerialBus Read/Write N Bytes protocol(ACPI Spec > > 5.5.2.4.5.3.8). Bios wants to read N Bytes when uses this protocol and the > > length specified by Bios should be greater than 1. If the Bios specified 0 > > bytes, the associated function(E,G read battery info) would be totally unusable. > > I think such Bios can't pass through Windows certification:). From this point, I > > think the check is not necessary. The simple question behind this is: Do I trust the caller? When I look at BIOS (or anything outside the kernel for that matter), I clearly say no, so... > > If you still thought this maybe happen, I think it makes more sense to add the > > check length in the ACPICA. Because ACPICA will allocate a data buffer for I2C > > ACPI operation region access before call the callback. The buffer length will be > > result of protocol head length plus data length. If data length is 0 and this > > means the access will be invalid and ACPICA should ignore it or produce a warning. ... I'd think such a check in ACPICA should be made. However, I can still ask the question if I trust callers outside my subsystem. This is more policy. We can demand that users of acpi_i2c_space_handler() should sanity check their arguments. Any foreseeable chance there will be another user other than ACPICA? I'd think no? Regards, Wolfram
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