From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60990) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aGT1Q-00039z-Ul for qemu-devel@nongnu.org; Tue, 05 Jan 2016 09:55:41 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aGT1P-0003oM-PJ for qemu-devel@nongnu.org; Tue, 05 Jan 2016 09:55:40 -0500 Received: from mx1.redhat.com ([209.132.183.28]:56430) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aGT1P-0003oA-JT for qemu-devel@nongnu.org; Tue, 05 Jan 2016 09:55:39 -0500 From: P J P Date: Tue, 5 Jan 2016 20:25:23 +0530 Message-Id: <1452005723-1494-2-git-send-email-ppandit@redhat.com> In-Reply-To: <1452005723-1494-1-git-send-email-ppandit@redhat.com> References: <1452005723-1494-1-git-send-email-ppandit@redhat.com> Subject: [Qemu-devel] [PATCH for v2.3.0] fw_cfg: add check to validate current entry value List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Qemu devel Cc: Stefan Weil , Prasad J Pandit , Peter Maydell From: Prasad J Pandit 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 --- 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