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5ffc88819c
At exit, perf record will kill the process it was profiling by sending a SIGTERM to child_pid (if it had been initialised), but in certain situations child_pid may be 0 and perf would mistakenly kill more processes than intended. child_pid is set to the return of fork() to either 0 or the pid of the child. Ordinarily this would not present an issue as the child calls execvp to spawn the process to be profiled and would therefore never run it's sig_atexit and never attempt to kill pid 0. However, if a nonexistant binary had been passed in to perf record the call to execvp would fail and child_pid would be left set to 0. The child would then exit and it's atexit handler, finding that child_pid was initialised to 0, would call kill(0, SIGTERM), resulting in every process within it's process group being killed. In the case that perf was being run directly from the shell this typically would not be an issue as the shell isolates the process. However, if perf was being called from another program it could kill unexpected processes, which may even include X. This patch changes the logic of the test for whether child_pid was initialised to only consider positive pids as valid, thereby never attempting to kill pid 0. Cc: David S. Miller <davem@davemloft.net> Cc: Frédéric Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Tom Zanussi <tzanussi@gmail.com> LKML-Reference: <1276072680-17378-1-git-send-email-imunsie@au1.ibm.com> Signed-off-by: Ian Munsie <imunsie@au1.ibm.com> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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