EDAC/thunderx: Fix possible out-of-bounds string access

Enabling -Wstringop-overflow globally exposes a warning for a common bug
in the usage of strncat():

  drivers/edac/thunderx_edac.c: In function 'thunderx_ocx_com_threaded_isr':
  drivers/edac/thunderx_edac.c:1136:17: error: 'strncat' specified bound 1024 equals destination size [-Werror=stringop-overflow=]
   1136 |                 strncat(msg, other, OCX_MESSAGE_SIZE);
        |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   ...
   1145 |                                 strncat(msg, other, OCX_MESSAGE_SIZE);
   ...
   1150 |                                 strncat(msg, other, OCX_MESSAGE_SIZE);

   ...

Apparently the author of this driver expected strncat() to behave the
way that strlcat() does, which uses the size of the destination buffer
as its third argument rather than the length of the source buffer. The
result is that there is no check on the size of the allocated buffer.

Change it to strlcat().

  [ bp: Trim compiler output, fixup commit message. ]

Fixes: 41003396 ("EDAC, thunderx: Add Cavium ThunderX EDAC driver")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20231122222007.3199885-1-arnd@kernel.org

drivers/edac/thunderx_edac.c

@@ -1133,7 +1133,7 @@ static irqreturn_t thunderx_ocx_com_threaded_isr(int irq, void *irq_id)
 		decode_register(other, OCX_OTHER_SIZE,
 				ocx_com_errors, ctx->reg_com_int);
 
-		strncat(msg, other, OCX_MESSAGE_SIZE);
+		strlcat(msg, other, OCX_MESSAGE_SIZE);
 
 		for (lane = 0; lane < OCX_RX_LANES; lane++)
 			if (ctx->reg_com_int & BIT(lane)) {
@@ -1142,12 +1142,12 @@ static irqreturn_t thunderx_ocx_com_threaded_isr(int irq, void *irq_id)
 					 lane, ctx->reg_lane_int[lane],
 					 lane, ctx->reg_lane_stat11[lane]);
 
-				strncat(msg, other, OCX_MESSAGE_SIZE);
+				strlcat(msg, other, OCX_MESSAGE_SIZE);
 
 				decode_register(other, OCX_OTHER_SIZE,
 						ocx_lane_errors,
 						ctx->reg_lane_int[lane]);
-				strncat(msg, other, OCX_MESSAGE_SIZE);
+				strlcat(msg, other, OCX_MESSAGE_SIZE);
 			}
 
 		if (ctx->reg_com_int & OCX_COM_INT_CE)
@@ -1217,7 +1217,7 @@ static irqreturn_t thunderx_ocx_lnk_threaded_isr(int irq, void *irq_id)
 		decode_register(other, OCX_OTHER_SIZE,
 				ocx_com_link_errors, ctx->reg_com_link_int);
 
-		strncat(msg, other, OCX_MESSAGE_SIZE);
+		strlcat(msg, other, OCX_MESSAGE_SIZE);
 
 		if (ctx->reg_com_link_int & OCX_COM_LINK_INT_UE)
 			edac_device_handle_ue(ocx->edac_dev, 0, 0, msg);
@@ -1896,7 +1896,7 @@ static irqreturn_t thunderx_l2c_threaded_isr(int irq, void *irq_id)
 
 		decode_register(other, L2C_OTHER_SIZE, l2_errors, ctx->reg_int);
 
-		strncat(msg, other, L2C_MESSAGE_SIZE);
+		strlcat(msg, other, L2C_MESSAGE_SIZE);
 
 		if (ctx->reg_int & mask_ue)
 			edac_device_handle_ue(l2c->edac_dev, 0, 0, msg);