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    Subject[PATCH 4.19 187/422] Drivers: hv: vmbus: Fix synic per-cpu context initialization
    Date
    From: Michael Kelley <mikelley@microsoft.com>

    [ Upstream commit f25a7ece08bdb1f2b3c4bbeae942682fc3a99dde ]

    If hv_synic_alloc() errors out, the state of the per-cpu context
    for some CPUs is unknown since the zero'ing is done as each
    CPU is iterated over. In such case, hv_synic_cleanup() may try to
    free memory based on uninitialized values. Fix this by zero'ing
    the per-cpu context for all CPUs before doing any memory
    allocations that might fail.

    Signed-off-by: Michael Kelley <mikelley@microsoft.com>
    Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
    Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/hv/hv.c | 15 ++++++++++++---
    1 file changed, 12 insertions(+), 3 deletions(-)

    diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
    index 8e923e70e5945..12bc9fa211117 100644
    --- a/drivers/hv/hv.c
    +++ b/drivers/hv/hv.c
    @@ -189,6 +189,17 @@ static void hv_init_clockevent_device(struct clock_event_device *dev, int cpu)
    int hv_synic_alloc(void)
    {
    int cpu;
    + struct hv_per_cpu_context *hv_cpu;
    +
    + /*
    + * First, zero all per-cpu memory areas so hv_synic_free() can
    + * detect what memory has been allocated and cleanup properly
    + * after any failures.
    + */
    + for_each_present_cpu(cpu) {
    + hv_cpu = per_cpu_ptr(hv_context.cpu_context, cpu);
    + memset(hv_cpu, 0, sizeof(*hv_cpu));
    + }

    hv_context.hv_numa_map = kcalloc(nr_node_ids, sizeof(struct cpumask),
    GFP_KERNEL);
    @@ -198,10 +209,8 @@ int hv_synic_alloc(void)
    }

    for_each_present_cpu(cpu) {
    - struct hv_per_cpu_context *hv_cpu
    - = per_cpu_ptr(hv_context.cpu_context, cpu);
    + hv_cpu = per_cpu_ptr(hv_context.cpu_context, cpu);

    - memset(hv_cpu, 0, sizeof(*hv_cpu));
    tasklet_init(&hv_cpu->msg_dpc,
    vmbus_on_msg_dpc, (unsigned long) hv_cpu);

    --
    2.20.1


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