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From:   Len Baker <len.baker@gmx.com>
To:     Vineet Gupta <vgupta@synopsys.com>
Cc:     Len Baker <len.baker@gmx.com>,
        "dean.yang_cp" <yangdianqing@yulong.com>,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        linux-snps-arc@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH] ARC: unwind: Use struct_size helper instead of open-coded arithmetic
Date:   Fri, 16 Jul 2021 19:03:44 +0200
Message-Id: <20210716170344.9150-1-len.baker@gmx.com>
MIME-Version: 1.0
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

Dynamic size calculations (especially multiplication) should not be
performed in memory allocator function arguments due to the risk of them
overflowing. This could lead to values wrapping around and a smaller
allocation being made than the caller was expecting. Using those
allocations could lead to linear overflows of heap memory and other
misbehaviors.

To avoid this scenario, use the struct_size helper.

Signed-off-by: Len Baker <len.baker@gmx.com>
=2D--
 arch/arc/kernel/unwind.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/arc/kernel/unwind.c b/arch/arc/kernel/unwind.c
index 47bab67f8649..af18052b86a7 100644
=2D-- a/arch/arc/kernel/unwind.c
+++ b/arch/arc/kernel/unwind.c
@@ -13,6 +13,7 @@
 #include <linux/sched.h>
 #include <linux/module.h>
 #include <linux/memblock.h>
+#include <linux/overflow.h>
 #include <linux/sort.h>
 #include <linux/slab.h>
 #include <linux/stop_machine.h>
@@ -312,9 +313,7 @@ static void init_unwind_hdr(struct unwind_table *table=
,
 	if (tableSize || !n)
 		goto ret_err;

-	hdrSize =3D 4 + sizeof(unsigned long) + sizeof(unsigned int)
-	    + 2 * n * sizeof(unsigned long);
-
+	hdrSize =3D struct_size(header, table, n);
 	header =3D alloc(hdrSize);
 	if (!header)
 		goto ret_err;
=2D-
2.25.1