From: Alexander Shishkin <alexander.shishkin@linux.intel.com> mainline inclusion from mainline-v5.5-rc3 commit 05b686b573cfb35a227c30787083a6631ff0f0c9 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I47H3V CVE: NA -------------------------------- 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@linux.intel.com> Fixes: 6cac7866c274 ("intel_th: msu: Add a sysfs attribute to trigger window switch") Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reported-by: Ammy Yi <ammy.yi@intel.com> Tested-by: Ammy Yi <ammy.yi@intel.com> Cc: stable@vger.kernel.org # v5.2+ Link: https://lore.kernel.org/r/20191217115527.74383-5-alexander.shishkin@linux.in... Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> Reviewed-by: Xie XiuQi <xiexiuqi@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- drivers/hwtracing/intel_th/msu.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/drivers/hwtracing/intel_th/msu.c b/drivers/hwtracing/intel_th/msu.c index 6b48362df260..2be1cb1e78a4 100644 --- a/drivers/hwtracing/intel_th/msu.c +++ b/drivers/hwtracing/intel_th/msu.c @@ -1669,10 +1669,13 @@ static int intel_th_msc_init(struct msc *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)) @@ -1684,6 +1687,8 @@ static void msc_win_switch(struct msc *msc) msc->base_addr = msc_win_baddr(msc->cur_win, 0); intel_th_trace_switch(msc->thdev); + + return 0; } /** @@ -2018,16 +2023,15 @@ win_switch_store(struct device *dev, struct device_attribute *attr, 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; -- 2.20.1