From: Greg Kroah-Hartman Date: Sun, 13 Jun 2021 13:08:20 +0000 (+0200) Subject: 4.4-stable patches X-Git-Tag: v4.4.273~44 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=ec5feb9ede3f7fb9e765be0d35aa38a08bb9b56a;p=thirdparty%2Fkernel%2Fstable-queue.git 4.4-stable patches added patches: perf-fix-data-race-between-pin_count-increment-decrement.patch --- diff --git a/queue-4.4/perf-fix-data-race-between-pin_count-increment-decrement.patch b/queue-4.4/perf-fix-data-race-between-pin_count-increment-decrement.patch new file mode 100644 index 00000000000..53c484fbdd6 --- /dev/null +++ b/queue-4.4/perf-fix-data-race-between-pin_count-increment-decrement.patch @@ -0,0 +1,48 @@ +From 6c605f8371159432ec61cbb1488dcf7ad24ad19a Mon Sep 17 00:00:00 2001 +From: Marco Elver +Date: Thu, 27 May 2021 12:47:11 +0200 +Subject: perf: Fix data race between pin_count increment/decrement + +From: Marco Elver + +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: fe4b04fa31a6 ("perf: Cure task_oncpu_function_call() races") +Reported-by: syzbot+142c9018f5962db69c7e@syzkaller.appspotmail.com +Signed-off-by: Marco Elver +Signed-off-by: Peter Zijlstra (Intel) +Link: https://lkml.kernel.org/r/20210527104711.2671610-1-elver@google.com +Signed-off-by: Greg Kroah-Hartman +--- + kernel/events/core.c | 2 ++ + 1 file changed, 2 insertions(+) + +--- a/kernel/events/core.c ++++ b/kernel/events/core.c +@@ -3497,7 +3497,9 @@ find_get_context(struct pmu *pmu, struct + cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu); + ctx = &cpuctx->ctx; + get_ctx(ctx); ++ raw_spin_lock_irqsave(&ctx->lock, flags); + ++ctx->pin_count; ++ raw_spin_unlock_irqrestore(&ctx->lock, flags); + + return ctx; + } diff --git a/queue-4.4/series b/queue-4.4/series index 208d0e721a9..ec99373a0ab 100644 --- a/queue-4.4/series +++ b/queue-4.4/series @@ -25,3 +25,4 @@ usb-serial-ftdi_sio-add-novatech-orionmx-product-id.patch usb-serial-omninet-add-device-id-for-zyxel-omni-56k-plus.patch usb-serial-quatech2-fix-control-request-directions.patch usb-gadget-eem-fix-wrong-eem-header-operation.patch +perf-fix-data-race-between-pin_count-increment-decrement.patch