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perf cs-etm: Always allocate memory for cs_etm_queue::prev_packet
Robert Walker reported a segmentation fault is observed when process CoreSight trace data; this issue can be easily reproduced by the command 'perf report --itrace=i1000i' for decoding tracing data. If neither the 'b' flag (synthesize branches events) nor 'l' flag (synthesize last branch entries) are specified to option '--itrace', cs_etm_queue::prev_packet will not been initialised. After merging the code to support exception packets and sample flags, there introduced a number of uses of cs_etm_queue::prev_packet without checking whether it is valid, for these cases any accessing to uninitialised prev_packet will cause crash. As cs_etm_queue::prev_packet is used more widely now and it's already hard to follow which functions have been called in a context where the validity of cs_etm_queue::prev_packet has been checked, this patch always allocates memory for cs_etm_queue::prev_packet. Reported-by: Robert Walker <[email protected]> Suggested-by: Robert Walker <[email protected]> Signed-off-by: Leo Yan <[email protected]> Tested-by: Robert Walker <[email protected]> Cc: Alexander Shishkin <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Mathieu Poirier <[email protected]> Cc: Mike Leach <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Suzuki K Poulouse <[email protected]> Cc: [email protected] Fixes: 7100b12 ("perf cs-etm: Generate branch sample for exception packet") Fixes: 24fff5e ("perf cs-etm: Avoid stale branch samples when flush packet") Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
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