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tcp: Replace strncpy() with strscpy()

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Replace the deprecated[1] uses of strncpy() in tcp_ca_get_name_by_key()
and tcp_get_default_congestion_control(). The callers use the results as
standard C strings (via nla_put_string() and proc handlers respectively),
so trailing padding is not needed.

Since passing the destination buffer arguments decays it to a pointer,
the size can't be trivially determined by the compiler. ca->name is
the same length in both cases, so strscpy() won't fail (when ca->name
is NUL-terminated). Include the length explicitly instead of using the
2-argument strscpy().

Link: https://github.com/KSPP/linux/issues/90 [1]
Signed-off-by: Kees Cook <kees@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20240714041111.it.918-kees@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kees Cook 2024-07-13 21:11:15 -07:00 committed by Jakub Kicinski
parent b49991d83b
commit a3bfc09506
1 changed files with 5 additions and 4 deletions
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9
net/ipv4/tcp_cong.c
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@ -202,9 +202,10 @@ char *tcp_ca_get_name_by_key(u32 key, char *buffer)
rcu_read_lock();
ca = tcp_ca_find_key(key);
if (ca)
ret = strncpy(buffer, ca->name,
TCP_CA_NAME_MAX);
if (ca) {
strscpy(buffer, ca->name, TCP_CA_NAME_MAX);
ret = buffer;
}
rcu_read_unlock();
return ret;
@ -337,7 +338,7 @@ void tcp_get_default_congestion_control(struct net *net, char *name)
rcu_read_lock();
ca = rcu_dereference(net->ipv4.tcp_congestion_control);
strncpy(name, ca->name, TCP_CA_NAME_MAX);
strscpy(name, ca->name, TCP_CA_NAME_MAX);
rcu_read_unlock();
}