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Re: [Qemu-stable] [PATCH v3 1/4] ivshmem: Check ivshmem_read() size argu
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-stable] [PATCH v3 1/4] ivshmem: Check ivshmem_read() size argument |
Date: |
Mon, 22 Sep 2014 14:21:12 +0300 |
On Mon, Sep 15, 2014 at 06:40:05PM +0200, Andreas Färber wrote:
> From: Stefan Hajnoczi <address@hidden>
>
> The third argument to the fd_read() callback implemented by
> ivshmem_read() is the number of bytes, not a flags field. Fix this and
> check we received enough bytes before accessing the buffer pointer.
>
> Cc: Cam Macdonell <address@hidden>
> Reported-by: Sebastian Krahmer <address@hidden>
> Signed-off-by: Stefan Hajnoczi <address@hidden>
> [AF: Handle partial reads via FIFO]
> Reported-by: Peter Maydell <address@hidden>
> Cc: address@hidden
> Signed-off-by: Andreas Färber <address@hidden>
Reviewed-by: Michael S. Tsirkin <address@hidden>
> ---
> hw/misc/ivshmem.c | 30 ++++++++++++++++++++++++++++--
> 1 file changed, 28 insertions(+), 2 deletions(-)
>
> diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
> index bd9d718..caeee1e 100644
> --- a/hw/misc/ivshmem.c
> +++ b/hw/misc/ivshmem.c
> @@ -24,6 +24,7 @@
> #include "migration/migration.h"
> #include "qapi/qmp/qerror.h"
> #include "qemu/event_notifier.h"
> +#include "qemu/fifo8.h"
> #include "sysemu/char.h"
>
> #include <sys/mman.h>
> @@ -73,6 +74,7 @@ typedef struct IVShmemState {
>
> CharDriverState **eventfd_chr;
> CharDriverState *server_chr;
> + Fifo8 incoming_fifo;
> MemoryRegion ivshmem_mmio;
>
> /* We might need to register the BAR before we actually have the memory.
> @@ -424,14 +426,35 @@ static void increase_dynamic_storage(IVShmemState *s,
> int new_min_size) {
> }
> }
>
> -static void ivshmem_read(void *opaque, const uint8_t * buf, int flags)
> +static void ivshmem_read(void *opaque, const uint8_t *buf, int size)
> {
> IVShmemState *s = opaque;
> int incoming_fd, tmp_fd;
> int guest_max_eventfd;
> long incoming_posn;
>
> - memcpy(&incoming_posn, buf, sizeof(long));
> + if (fifo8_is_empty(&s->incoming_fifo) && size == sizeof(incoming_posn)) {
> + memcpy(&incoming_posn, buf, size);
> + } else {
> + const uint8_t *p;
> + uint32_t num;
> +
> + IVSHMEM_DPRINTF("short read of %d bytes\n", size);
> + num = MAX(size, sizeof(long) - fifo8_num_used(&s->incoming_fifo));
> + fifo8_push_all(&s->incoming_fifo, buf, num);
> + if (fifo8_num_used(&s->incoming_fifo) < sizeof(incoming_posn)) {
> + return;
> + }
> + size -= num;
> + buf += num;
> + p = fifo8_pop_buf(&s->incoming_fifo, sizeof(incoming_posn), &num);
> + g_assert(num == sizeof(incoming_posn));
> + memcpy(&incoming_posn, p, sizeof(incoming_posn));
> + if (size > 0) {
> + fifo8_push_all(&s->incoming_fifo, buf, size);
> + }
> + }
> +
> /* pick off s->server_chr->msgfd and store it, posn should accompany msg
> */
> tmp_fd = qemu_chr_fe_get_msgfd(s->server_chr);
> IVSHMEM_DPRINTF("posn is %ld, fd is %d\n", incoming_posn, tmp_fd);
> @@ -663,6 +686,8 @@ static int pci_ivshmem_init(PCIDevice *dev)
> s->ivshmem_size = ivshmem_get_size(s);
> }
>
> + fifo8_create(&s->incoming_fifo, sizeof(long));
> +
> register_savevm(DEVICE(dev), "ivshmem", 0, 0, ivshmem_save, ivshmem_load,
> dev);
>
> @@ -796,6 +821,7 @@ static void pci_ivshmem_uninit(PCIDevice *dev)
> memory_region_del_subregion(&s->bar, &s->ivshmem);
> vmstate_unregister_ram(&s->ivshmem, DEVICE(dev));
> unregister_savevm(DEVICE(dev), "ivshmem", s);
> + fifo8_destroy(&s->incoming_fifo);
> }
>
> static Property ivshmem_properties[] = {
> --
> 1.8.4.5