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

[ Upstream commit 475c58e1a471e9b873e3e39958c64a2d278275c8 ]

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: 41003396f932 ("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: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/edac/thunderx_edac.c b/drivers/edac/thunderx_edac.c
index b9c5772..90d46e5 100644 (file)
--- a/drivers/edac/thunderx_edac.c
+++ b/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);