Marco Elver c64a3be39f perf: Fix data race between pin_count increment/decrement ... commit 6c605f8371159432ec61cbb1488dcf7ad24ad19a upstream. KCSAN reports a data race between increment and decrement of pin_count: write to 0xffff888237c2d4e0 of 4 bytes by task 15740 on cpu 1: find_get_context kernel/events/core.c:4617 __do_sys_perf_event_open kernel/events/core.c:12097 [inline] __se_sys_perf_event_open kernel/events/core.c:11933 ... read to 0xffff888237c2d4e0 of 4 bytes by task 15743 on cpu 0: perf_unpin_context kernel/events/core.c:1525 [inline] __do_sys_perf_event_open kernel/events/core.c:12328 [inline] __se_sys_perf_event_open kernel/events/core.c:11933 ... Because neither read-modify-write here is atomic, this can lead to one of the operations being lost, resulting in an inconsistent pin_count. Fix it by adding the missing locking in the CPU-event case. Fixes: fe4b04fa31 ("perf: Cure task_oncpu_function_call() races") Reported-by: syzbot+142c9018f5962db69c7e@syzkaller.appspotmail.com Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210527104711.2671610-1-elver@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2021-06-16 12:01:45 +02:00
..
callchain.c	uaccess: add force_uaccess_{begin,end} helpers	2020-08-12 10:57:59 -07:00
core.c	perf: Fix data race between pin_count increment/decrement	2021-06-16 12:01:45 +02:00
hw_breakpoint.c	powerpc/watchpoint: Don't allow concurrent perf and ptrace events	2020-05-19 00:14:45 +10:00
internal.h	perf: Optimize get_recursion_context()	2020-11-09 18:12:34 +01:00
Makefile
ring_buffer.c	perf: Reduce stack usage of perf_output_begin()	2020-11-09 18:12:33 +01:00
uprobes.c	task_work: cleanup notification modes	2020-10-17 15:05:30 -06:00