From 5a18ea7d864c0fb2c94c1149f5d3ddabca4123fe Mon Sep 17 00:00:00 2001 From: Erick Archer Date: Sat, 27 Apr 2024 19:23:36 +0200 Subject: [PATCH] sctp: prefer struct_size over open coded arithmetic [ Upstream commit e5c5f3596de224422561d48eba6ece5210d967b3 ] 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 Acked-by: Xin Long Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/PAXPR02MB724871DB78375AB06B5171C88B152@PAXPR02MB7248.eurprd02.prod.outlook.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- net/sctp/socket.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/net/sctp/socket.c b/net/sctp/socket.c index bc4fe944ef85..79cf4cda2cf6 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -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;