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sctp: prefer struct_size over open coded arithmetic

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[ Upstream commit e5c5f3596d ]

This is an effort to get rid of all multiplications from allocation
functions in order to prevent integer overflows [1][2].

As the "ids" variable is a pointer to "struct sctp_assoc_ids" and this
structure ends in a flexible array:

struct sctp_assoc_ids {
	[...]
	sctp_assoc_t	gaids_assoc_id[];
};

the preferred way in the kernel is to use the struct_size() helper to
do the arithmetic instead of the calculation "size + size * count" in
the kmalloc() function.

Also, refactor the code adding the "ids_size" variable to avoid sizing
twice.

This way, the code is more readable and safer.

This code was detected with the help of Coccinelle, and audited and
modified manually.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1]
Link: https://github.com/KSPP/linux/issues/160 [2]
Signed-off-by: Erick Archer <erick.archer@outlook.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/PAXPR02MB724871DB78375AB06B5171C88B152@PAXPR02MB7248.eurprd02.prod.outlook.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Erick Archer 2024-04-27 19:23:36 +02:00 committed by Greg Kroah-Hartman
parent 4dcce63a6f
commit 5a18ea7d86
1 changed files with 4 additions and 3 deletions
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7
net/sctp/socket.c
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@ -6994,6 +6994,7 @@ static int sctp_getsockopt_assoc_ids(struct sock *sk, int len,
struct sctp_sock *sp = sctp_sk(sk);
struct sctp_association *asoc;
struct sctp_assoc_ids *ids;
size_t ids_size;
u32 num = 0;
if (sctp_style(sk, TCP))
@ -7006,11 +7007,11 @@ static int sctp_getsockopt_assoc_ids(struct sock *sk, int len,
num++;
}
if (len < sizeof(struct sctp_assoc_ids) + sizeof(sctp_assoc_t) * num)
ids_size = struct_size(ids, gaids_assoc_id, num);
if (len < ids_size)
return -EINVAL;
len = sizeof(struct sctp_assoc_ids) + sizeof(sctp_assoc_t) * num;
len = ids_size;
ids = kmalloc(len, GFP_USER | __GFP_NOWARN);
if (unlikely(!ids))
return -ENOMEM;