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[Qemu-stable] [PATCH for v2.5.1] fw_cfg: avoid calculating invalid curre
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[Qemu-stable] [PATCH for v2.5.1] fw_cfg: avoid calculating invalid current entry pointer |
Date: |
Tue, 26 Jan 2016 00:38:30 +0530 |
From: "Gabriel L. Somlo" <address@hidden>
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 <address@hidden>
Reviewed-by: Laszlo Ersek <address@hidden>
Signed-off-by: Gabriel Somlo <address@hidden>
Message-id: address@hidden
Cc: Marc MarĂ <address@hidden>
Signed-off-by: Gabriel Somlo <address@hidden>
Reviewed-by: Laszlo Ersek <address@hidden>
Signed-off-by: Gerd Hoffmann <address@hidden>
(cherry picked from commit 66f8fd9dda312191b78d2a2ba2848bcee76127a2)
Signed-off-by: Prasad J Pandit <address@hidden>
---
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;
--
2.5.0
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