From: Prasad J Pandit <p...@fedoraproject.org> When processing firmware configurations, an OOB r/w access occurs if 's->cur_entry' is set to be invalid(FW_CFG_INVALID=0xffff). Add a check to validate 's->cur_entry' to avoid such access.
Reported-by: Donghai Zdh <donghai....@alibaba-inc.com> Signed-off-by: Prasad J Pandit <p...@fedoraproject.org> --- hw/nvram/fw_cfg.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c index 68eff77..ce026bc 100644 --- a/hw/nvram/fw_cfg.c +++ b/hw/nvram/fw_cfg.c @@ -233,12 +233,15 @@ static void fw_cfg_reboot(FWCfgState *s) static void fw_cfg_write(FWCfgState *s, uint8_t value) { 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]; trace_fw_cfg_write(s, value); - if (s->cur_entry & FW_CFG_WRITE_CHANNEL && e->callback && - s->cur_offset < e->len) { + if (s->cur_entry != FW_CFG_INVALID + && s->cur_entry & FW_CFG_WRITE_CHANNEL + && e->callback + && s->cur_offset < e->len) { e->data[s->cur_offset++] = value; if (s->cur_offset == e->len) { e->callback(e->callback_opaque, e->data); @@ -267,7 +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) -- 2.4.3