On 11/03/15 22:40, Gabriel L. Somlo wrote:
> When calculating a pointer to the currently selected fw_cfg item, the
> following is used:
>
> FWCfgEntry *e = &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK];
>
> When s->cur_entry is FW_CFG_INVALID, we are calculating the address of
> a non-existent element in s->entries[arch][...], which is undefined.
>
> This patch ensures the resulting entry pointer is se to NULL whenever
se[t] to NULL
> s->cur_entry is FW_CFG_INVALID.
>
> Reported-by: Laszlo Ersek <ler...@redhat.com>
> Cc: Marc Marí <mar...@redhat.com>
> Signed-off-by: Gabriel Somlo <so...@cmu.edu>
> ---
> hw/nvram/fw_cfg.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
> index c2d3a0a..046fa74 100644
> --- a/hw/nvram/fw_cfg.c
> +++ b/hw/nvram/fw_cfg.c
> @@ -277,7 +277,8 @@ static int fw_cfg_select(FWCfgState *s, uint16_t key)
> static uint8_t fw_cfg_read(FWCfgState *s)
> {
> int arch = !!(s->cur_entry & FW_CFG_ARCH_LOCAL);
> - FWCfgEntry *e = &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK];
> + FWCfgEntry *e = (s->cur_entry == FW_CFG_INVALID) ? NULL :
> + &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK];
> uint8_t ret;
>
> if (s->cur_entry == FW_CFG_INVALID || !e->data || s->cur_offset >=
> e->len)
> @@ -342,7 +343,8 @@ static void fw_cfg_dma_transfer(FWCfgState *s)
> }
>
> arch = !!(s->cur_entry & FW_CFG_ARCH_LOCAL);
> - e = &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK];
> + e = (s->cur_entry == FW_CFG_INVALID) ? NULL :
> + &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK];
>
> if (dma.control & FW_CFG_DMA_CTL_READ) {
> read = 1;
>
Reviewed-by: Laszlo Ersek <ler...@redhat.com>
