From baba731bc6e7920ec2dca7d449b6bf7d42e4901f Mon Sep 17 00:00:00 2001 From: =?utf8?q?Philippe=20Mathieu-Daud=C3=A9?= Date: Fri, 14 Feb 2020 01:47:53 +0100 Subject: [PATCH] hw/net/i82596: Correct command bitmask (CID 1419392) MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The command is 32-bit, but we are loading the 16 upper bits with the 'get_uint16(s->scb + 2)' call. Once shifted by 16, the command bits match the status bits: - Command Bit 31 ACK-CX Acknowledges that the CU completed an Action Command. Bit 30 ACK-FR Acknowledges that the RU received a frame. Bit 29 ACK-CNA Acknowledges that the Command Unit became not active. Bit 28 ACK-RNR Acknowledges that the Receive Unit became not ready. - Status Bit 15 CX The CU finished executing a command with its I(interrupt) bit set. Bit 14 FR The RU finished receiving a frame. Bit 13 CNA The Command Unit left the Active state. Bit 12 RNR The Receive Unit left the Ready state. Add the SCB_COMMAND_ACK_MASK definition to simplify the code. This fixes Coverity 1419392 (CONSTANT_EXPRESSION_RESULT): /hw/net/i82596.c: 352 in examine_scb() 346 cuc = (command >> 8) & 0x7; 347 ruc = (command >> 4) & 0x7; 348 DBG(printf("MAIN COMMAND %04x cuc %02x ruc %02x\n", command, cuc, ruc)); 349 /* and clear the scb command word */ 350 set_uint16(s->scb + 2, 0); 351 >>> CID 1419392: (CONSTANT_EXPRESSION_RESULT) >>> "command & (2147483648UL /* 1UL << 31 */)" is always 0 regardless of the values of its operands. This occurs as the logical operand of "if". 352 if (command & BIT(31)) /* ACK-CX */ 353 s->scb_status &= ~SCB_STATUS_CX; >>> CID 1419392: (CONSTANT_EXPRESSION_RESULT) >>> "command & (1073741824UL /* 1UL << 30 */)" is always 0 regardless of the values of its operands. This occurs as the logical operand of "if". 354 if (command & BIT(30)) /*ACK-FR */ 355 s->scb_status &= ~SCB_STATUS_FR; >>> CID 1419392: (CONSTANT_EXPRESSION_RESULT) >>> "command & (536870912UL /* 1UL << 29 */)" is always 0 regardless of the values of its operands. This occurs as the logical operand of "if". 356 if (command & BIT(29)) /*ACK-CNA */ 357 s->scb_status &= ~SCB_STATUS_CNA; >>> CID 1419392: (CONSTANT_EXPRESSION_RESULT) >>> "command & (268435456UL /* 1UL << 28 */)" is always 0 regardless of the values of its operands. This occurs as the logical operand of "if". 358 if (command & BIT(28)) /*ACK-RNR */ 359 s->scb_status &= ~SCB_STATUS_RNR; Fixes: Covertiy CID 1419392 (commit 376b851909) Signed-off-by: Philippe Mathieu-Daudé Reviewed-by: Peter Maydell Signed-off-by: Jason Wang --- hw/net/i82596.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) diff --git a/hw/net/i82596.c b/hw/net/i82596.c index fe9f2390a9..ecdb9aa4f8 100644 --- a/hw/net/i82596.c +++ b/hw/net/i82596.c @@ -43,6 +43,9 @@ #define SCB_STATUS_CNA 0x2000 /* CU left active state */ #define SCB_STATUS_RNR 0x1000 /* RU left active state */ +#define SCB_COMMAND_ACK_MASK \ + (SCB_STATUS_CX | SCB_STATUS_FR | SCB_STATUS_CNA | SCB_STATUS_RNR) + #define CU_IDLE 0 #define CU_SUSPENDED 1 #define CU_ACTIVE 2 @@ -348,14 +351,7 @@ static void examine_scb(I82596State *s) /* and clear the scb command word */ set_uint16(s->scb + 2, 0); - if (command & BIT(31)) /* ACK-CX */ - s->scb_status &= ~SCB_STATUS_CX; - if (command & BIT(30)) /*ACK-FR */ - s->scb_status &= ~SCB_STATUS_FR; - if (command & BIT(29)) /*ACK-CNA */ - s->scb_status &= ~SCB_STATUS_CNA; - if (command & BIT(28)) /*ACK-RNR */ - s->scb_status &= ~SCB_STATUS_RNR; + s->scb_status &= ~(command & SCB_COMMAND_ACK_MASK); switch (cuc) { case 0: /* no change */ -- 2.11.0