This is a note to let you know that I've just added the patch titled intel_th: msu: Fix window switching without windows to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: intel_th-msu-fix-window-switching-without-windows.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 05b686b573cfb35a227c30787083a6631ff0f0c9 Mon Sep 17 00:00:00 2001 From: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx> Date: Tue, 17 Dec 2019 13:55:27 +0200 Subject: intel_th: msu: Fix window switching without windows From: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx> commit 05b686b573cfb35a227c30787083a6631ff0f0c9 upstream. Commit 6cac7866c2741 ("intel_th: msu: Add a sysfs attribute to trigger window switch") adds a NULL pointer dereference in the case when there are no windows allocated: > BUG: kernel NULL pointer dereference, address: 0000000000000000 > #PF: supervisor read access in kernel mode > #PF: error_code(0x0000) - not-present page > PGD 0 P4D 0 > Oops: 0000 1 SMP > CPU: 5 PID: 1110 Comm: bash Not tainted 5.5.0-rc1+ #1 > RIP: 0010:msc_win_switch+0xa/0x80 [intel_th_msu] > Call Trace: > ? win_switch_store+0x9b/0xc0 [intel_th_msu] > dev_attr_store+0x17/0x30 > sysfs_kf_write+0x3e/0x50 > kernfs_fop_write+0xda/0x1b0 > __vfs_write+0x1b/0x40 > vfs_write+0xb9/0x1a0 > ksys_write+0x67/0xe0 > __x64_sys_write+0x1a/0x20 > do_syscall_64+0x57/0x1d0 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fix that by disallowing window switching with multiwindow buffers without windows. Signed-off-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx> Fixes: 6cac7866c274 ("intel_th: msu: Add a sysfs attribute to trigger window switch") Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Reported-by: Ammy Yi <ammy.yi@xxxxxxxxx> Tested-by: Ammy Yi <ammy.yi@xxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx # v5.2+ Link: https://lore.kernel.org/r/20191217115527.74383-5-alexander.shishkin@xxxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/hwtracing/intel_th/msu.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) --- a/drivers/hwtracing/intel_th/msu.c +++ b/drivers/hwtracing/intel_th/msu.c @@ -1676,10 +1676,13 @@ static int intel_th_msc_init(struct msc return 0; } -static void msc_win_switch(struct msc *msc) +static int msc_win_switch(struct msc *msc) { struct msc_window *first; + if (list_empty(&msc->win_list)) + return -EINVAL; + first = list_first_entry(&msc->win_list, struct msc_window, entry); if (msc_is_last_win(msc->cur_win)) @@ -1691,6 +1694,8 @@ static void msc_win_switch(struct msc *m msc->base_addr = msc_win_base_dma(msc->cur_win); intel_th_trace_switch(msc->thdev); + + return 0; } /** @@ -2025,16 +2030,15 @@ win_switch_store(struct device *dev, str if (val != 1) return -EINVAL; + ret = -EINVAL; mutex_lock(&msc->buf_mutex); /* * Window switch can only happen in the "multi" mode. * If a external buffer is engaged, they have the full * control over window switching. */ - if (msc->mode != MSC_MODE_MULTI || msc->mbuf) - ret = -ENOTSUPP; - else - msc_win_switch(msc); + if (msc->mode == MSC_MODE_MULTI && !msc->mbuf) + ret = msc_win_switch(msc); mutex_unlock(&msc->buf_mutex); return ret ? ret : size; Patches currently in stable-queue which might be from alexander.shishkin@xxxxxxxxxxxxxxx are queue-5.4/perf-jevents-fix-resource-leak-in-process_mapfile-an.patch queue-5.4/perf-tools-fix-cross-compile-for-arm64.patch queue-5.4/perf-cs-etm-fix-definition-of-macro-to_cs_queue_nr.patch queue-5.4/intel_th-pci-add-elkhart-lake-soc-support.patch queue-5.4/intel_th-pci-add-comet-lake-pch-v-support.patch queue-5.4/perf-report-add-warning-when-libunwind-not-compiled-.patch queue-5.4/perf-vendor-events-arm64-fix-hisi-hip08-ddrc-pmu-eve.patch queue-5.4/perf-session-fix-decompression-of-perf_record_compre.patch queue-5.4/perf-test-avoid-infinite-loop-for-task-exit-case.patch queue-5.4/perf-tests-disable-bp_signal-testing-for-arm64.patch queue-5.4/perf-core-fix-the-mlock-accounting-again.patch queue-5.4/perf-test-report-failure-for-mmap-events.patch queue-5.4/perf-parse-fix-potential-memory-leak-when-handling-t.patch queue-5.4/perf-tools-splice-events-onto-evlist-even-on-error.patch queue-5.4/intel_th-msu-fix-window-switching-without-windows.patch queue-5.4/perf-parse-if-pmu-configuration-fails-free-terms.patch queue-5.4/intel_th-fix-freeing-irqs.patch