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Date:   Sun, 19 Sep 2021 11:45:39 +0200
From:   Len Baker <>
To:     Benjamin LaHaise <>,
        Alexander Viro <>
Cc:     Len Baker <>, Kees Cook <>,
        "Gustavo A. R. Silva" <>,,,,
Subject: [PATCH] aio: 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 + size * count" in the kzalloc() function.


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

diff --git a/fs/aio.c b/fs/aio.c
index 51b08ab01dff..c2978c0b872c 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -659,8 +659,7 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
 		new_nr = (table ? table->nr : 1) * 4;

-		table = kzalloc(sizeof(*table) + sizeof(struct kioctx *) *
-				new_nr, GFP_KERNEL);
+		table = kzalloc(struct_size(table, table, new_nr), GFP_KERNEL);
 		if (!table)
 			return -ENOMEM;


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