[PATCH] net/txgbe: fix out of bound access

[Ferruh Yigit]

Reported by SuSe CI [1] by GCC [2], possibly false positive. Error:

 In function 'txgbe_host_interface_command',
     inlined from 'txgbe_host_interface_command'
             at ../drivers/net/txgbe/base/txgbe_mng.c:104:1,
     inlined from 'txgbe_hic_reset'
             at ../drivers/net/txgbe/base/txgbe_mng.c:345:9:
 ../drivers/net/txgbe/base/txgbe_mng.c:145:36:
    error: array subscript 2 is outside array bounds ofr
           'struct txgbe_hic_reset[1]' [-Werror=array-bounds=]
   145 |                     buffer[bi] = rd32a(hw, TXGBE_MNGMBX, bi);
 ../drivers/net/txgbe/base/txgbe_mng.c: In function 'txgbe_hic_reset':
 ../drivers/net/txgbe/base/txgbe_mng.c:331:32:
    note: at offset 8 into object 'reset_cmd' of size 8
   331 |         struct txgbe_hic_reset reset_cmd;
       |                                ^~~~~~~~~

Access to buffer done based on command code, the case complained by
FW_RESET_CMD has short buffer but this code path only taken with command
0x30, so this shouldn't be a problem.

Adding a size check before accessing to the buffer, as this is control
plane code, additional check shouldn't hurt.

[1]
https://build.opensuse.org/public/build/home:bluca:dpdk/openSUSE_Factory_ARM/armv7l/dpdk-20.11/_log

[2]
gcc 13.2.1 "cc (SUSE Linux) 13.2.1 20230912

Fixes: 35c90ecccfd4 ("net/txgbe: add EEPROM functions")
Cc: stable at dpdk.org

Reported-by: Luca Boccassi <luca.boccassi at microsoft.com>
Signed-off-by: Ferruh Yigit <ferruh.yigit at amd.com>
---
Cc: jiawenwu at trustnetic.com
Cc: jianwang at trustnetic.com

@Luca, I am not sure if this additional check will satisfy the compiler,
can you please verify the patch?

@Jiawen, there is a specific handling for command 0x30, from comment it
looks like it is Read Flash command, but it looks like this command is
not used by the driver, if this is correct can we remove the check
completely? Removing can be simpler way to fix the compiler error.
---
 drivers/net/txgbe/base/txgbe_mng.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/txgbe/base/txgbe_mng.c b/drivers/net/txgbe/base/txgbe_mng.c
index df7145094f84..9797b1b8b5da 100644
--- a/drivers/net/txgbe/base/txgbe_mng.c
+++ b/drivers/net/txgbe/base/txgbe_mng.c
@@ -147,6 +147,10 @@ txgbe_host_interface_command(struct txgbe_hw *hw, u32 *buffer,
 	 * two byes instead of one byte
 	 */
 	if (resp->cmd == 0x30) {
+		if (length < ((dword_len + 2) << 2)) {
+			err = TXGBE_ERR_HOST_INTERFACE_COMMAND;
+			goto rel_out;
+		}
 		for (; bi < dword_len + 2; bi++)
 			buffer[bi] = rd32a(hw, TXGBE_MNGMBX, bi);
 
-- 
2.34.1