intel_th: msu: Fix window switching without windows
commit05b686b573
upstream. Commit6cac7866c2
("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:6cac7866c2
("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.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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parent
6e5e603e7e
commit
0cef149aa5
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@ -1676,10 +1676,13 @@ static int intel_th_msc_init(struct msc *msc)
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return 0;
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}
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static void msc_win_switch(struct msc *msc)
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static int msc_win_switch(struct msc *msc)
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{
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struct msc_window *first;
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if (list_empty(&msc->win_list))
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return -EINVAL;
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first = list_first_entry(&msc->win_list, struct msc_window, entry);
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if (msc_is_last_win(msc->cur_win))
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@ -1691,6 +1694,8 @@ static void msc_win_switch(struct msc *msc)
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msc->base_addr = msc_win_base_dma(msc->cur_win);
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intel_th_trace_switch(msc->thdev);
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return 0;
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}
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/**
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@ -2025,16 +2030,15 @@ win_switch_store(struct device *dev, struct device_attribute *attr,
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if (val != 1)
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return -EINVAL;
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ret = -EINVAL;
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mutex_lock(&msc->buf_mutex);
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/*
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* Window switch can only happen in the "multi" mode.
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* If a external buffer is engaged, they have the full
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* control over window switching.
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*/
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if (msc->mode != MSC_MODE_MULTI || msc->mbuf)
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ret = -ENOTSUPP;
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else
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msc_win_switch(msc);
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if (msc->mode == MSC_MODE_MULTI && !msc->mbuf)
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ret = msc_win_switch(msc);
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mutex_unlock(&msc->buf_mutex);
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return ret ? ret : size;
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