From: "Gabriel L. Somlo" <[email protected]> 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 set to NULL whenever s->cur_entry is FW_CFG_INVALID. Reported-by: Laszlo Ersek <[email protected]> Reviewed-by: Laszlo Ersek <[email protected]> Signed-off-by: Gabriel Somlo <[email protected]> Message-id: [email protected] Cc: Marc Marí <[email protected]> Signed-off-by: Gabriel Somlo <[email protected]> Reviewed-by: Laszlo Ersek <[email protected]> Signed-off-by: Gerd Hoffmann <[email protected]> (cherry picked from commit 66f8fd9dda312191b78d2a2ba2848bcee76127a2) Signed-off-by: Michael Roth <[email protected]> --- 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 73b0a81..117809b 100644 --- a/hw/nvram/fw_cfg.c +++ b/hw/nvram/fw_cfg.c @@ -270,7 +270,8 @@ 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) @@ -338,7 +339,8 @@ 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; -- 1.9.1
