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* [PATCH] MdeModulePkg/TerminalDxe [BUG]: Terminal fifo buffer overflow.
@ 2021-01-14  3:22 gechao
  2021-01-14  6:34 ` Gao, Zhichao
       [not found] ` <165A05B49BF7F07B.12403@groups.io>
  0 siblings, 2 replies; 4+ messages in thread
From: gechao @ 2021-01-14  3:22 UTC (permalink / raw)
  To: zhichao.gao; +Cc: devel, ray.ni, gechao

From: gechao <gechao@greatwall.com.cn>

Fix the bug of terminal fifo buffer overflow with UINT8 type.

typedef struct {
  UINT8 Head;
  UINT8 Tail;
  UINT8 Data[RAW_FIFO_MAX_NUMBER + 1];
} RAW_DATA_FIFO;
RAW_FIFO_MAX_NUMBER is 256.
the data buffer size is 257 (Index from 0 to 256), but the max value of
the index, Head or Tail (UINT8), is 255. That means the last data of the
data buffer would be always empty if we use Head/Tail to output/input the
data correctly.  And because of the incorrect buffer size the FIFO full
check "((Tail + 1) % (RAW_FIFO_MAX_NUMBER + 1)) == Head" would never meet.

Signed-off-by: gechao <gechao@greatwall.com.cn>
---
 MdeModulePkg/Universal/Console/TerminalDxe/Terminal.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/MdeModulePkg/Universal/Console/TerminalDxe/Terminal.h b/MdeModulePkg/Universal/Console/TerminalDxe/Terminal.h
index 378ace13ce..360e58e847 100644
--- a/MdeModulePkg/Universal/Console/TerminalDxe/Terminal.h
+++ b/MdeModulePkg/Universal/Console/TerminalDxe/Terminal.h
@@ -37,7 +37,7 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 #include <Library/BaseLib.h>
 
 
-#define RAW_FIFO_MAX_NUMBER 256
+#define RAW_FIFO_MAX_NUMBER 255
 #define FIFO_MAX_NUMBER     128
 
 typedef struct {
-- 
2.25.1


^ permalink raw reply related	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2021-01-15  8:53 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2021-01-14  3:22 [PATCH] MdeModulePkg/TerminalDxe [BUG]: Terminal fifo buffer overflow gechao
2021-01-14  6:34 ` Gao, Zhichao
     [not found] ` <165A05B49BF7F07B.12403@groups.io>
2021-01-15  8:49   ` [edk2-devel] " Gao, Zhichao
2021-01-15  8:53     ` Wu, Hao A

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