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

JIRA: https://issues.redhat.com/browse/RHEL-26577
Tested: sanity
CVE: CVE-2023-52464

commit 475c58e
Author: Arnd Bergmann <arnd@arndb.de>
Date:   Wed Nov 22 23:19:53 2023 +0100

    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: 4100339 ("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

Signed-off-by: Aristeu Rozanski <arozansk@redhat.com>

Author: aristeu

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);