Messages in this thread | | | Date | Wed, 6 Jul 2022 10:13:22 -0600 | From | Keith Busch <> | Subject | Re: [PATCH] nvme: Fix nvme_setup_command metadata trace event for cdw10 |
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On Wed, Jul 06, 2022 at 04:16:38PM +0800, John Garry wrote: > For x86_64 allmodconfig I get this warning: > > In function ‘fortify_memcpy_chk’, > inlined from ‘perf_trace_nvme_setup_cmd’ at drivers/nvme/host/./trace.h:47:1: > ./include/linux/fortify-string.h:352:4: error: call to ‘__read_overflow2_field’ declared with attribute warning: detected read beyond size of field (2nd parameter); maybe use struct_group()? [-Werror] > __read_overflow2_field(q_size_field, size); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > In function ‘fortify_memcpy_chk’, > inlined from ‘trace_event_raw_event_nvme_setup_cmd’ at drivers/nvme/host/./trace.h:47:1: > ./include/linux/fortify-string.h:352:4: error: call to ‘__read_overflow2_field’ declared with attribute warning: detected read beyond size of field (2nd parameter); maybe use struct_group()? [-Werror] > __read_overflow2_field(q_size_field, size); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > cdw10 metadata is 24 bytes, and we try to copy size of cdw10 metadata from > nvme_command.common.cdw10 into that cdw10 metadata, but > nvme_command.common.cdw10 is only 4 bytes in size. > > Fix by making the trace metadata size as 4 bytes. > > I find that this warning started first appearing from commit f68f2ff91512 > ("fortify: Detect struct member overflows in memcpy() at compile-time").
Did you test what the trace looks like afte this? We're losing valuable trace data here. The field is supposed to get CDW's 10 - 15, so that's 24 bytes. I don't know why it cares that the address of the field being read is only 4 bytes; we want everything that comes after it too.
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