From f662c5972a54f2f4b218d9ace5c3b10ae9a15b7e Mon Sep 17 00:00:00 2001 From: Prasad J Pandit Date: Wed, 6 Jan 2016 11:46:25 +0530 Subject: [PATCH] fw_cfg: add check to validate current entry value 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 Signed-off-by: Prasad J Pandit Signed-off-by: Stefano Stabellini --- 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 282341ac1..89fde41d8 100644 --- a/hw/nvram/fw_cfg.c +++ b/hw/nvram/fw_cfg.c @@ -211,12 +211,15 @@ 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_WRITE_CHANNEL + && e != NULL + && 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); @@ -245,7 +248,8 @@ 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) -- 2.39.5