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Date:   Sat, 11 Sep 2021 15:19:33 +0200
From:   Len Baker <>
To:     Maxim Levitsky <>,
        Alex Dubov <>,
        Ulf Hansson <>
Cc:     Len Baker <>, Kees Cook <>,
        Tom Rix <>,,,
Subject: [PATCH] memstick: jmb38x_ms: Prefer struct_size over open coded arithmetic

As noted in the "Deprecated Interfaces, Language Features, Attributes,
and Conventions" documentation [1], size calculations (especially
multiplication) should not be performed in memory allocator (or similar)
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.

So, use the struct_size() helper to do the arithmetic instead of the
argument "size + count * size" in the kzalloc() function.


Signed-off-by: Len Baker <>
 drivers/memstick/host/jmb38x_ms.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/memstick/host/jmb38x_ms.c b/drivers/memstick/host/jmb38x_ms.c
index f9a93b0565e1..a7a0f0caea15 100644
--- a/drivers/memstick/host/jmb38x_ms.c
+++ b/drivers/memstick/host/jmb38x_ms.c
@@ -927,8 +927,7 @@ static int jmb38x_ms_probe(struct pci_dev *pdev,
 		goto err_out_int;

-	jm = kzalloc(sizeof(struct jmb38x_ms)
-		     + cnt * sizeof(struct memstick_host *), GFP_KERNEL);
+	jm = kzalloc(struct_size(jm, hosts, cnt), GFP_KERNEL);
 	if (!jm) {
 		rc = -ENOMEM;
 		goto err_out_int;

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