netdev - [PATCH net v3 2/4] llc: Improve setsockopt() handling of malformed user input

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Message-Id: <20241119-sockptr-copy-fixes-v3-2-d752cac4be8e@rbox.co>
Date: Tue, 19 Nov 2024 14:31:41 +0100
From: Michal Luczaj <mhal@...x.co>
To: Marcel Holtmann <marcel@...tmann.org>, 
 Johan Hedberg <johan.hedberg@...il.com>, 
 Luiz Augusto von Dentz <luiz.dentz@...il.com>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, 
 David Howells <dhowells@...hat.com>, Marc Dionne <marc.dionne@...istor.com>
Cc: Luiz Augusto von Dentz <luiz.von.dentz@...el.com>, 
 linux-bluetooth@...r.kernel.org, netdev@...r.kernel.org, 
 linux-afs@...ts.infradead.org, Jakub Kicinski <kuba@...nel.org>, 
 Michal Luczaj <mhal@...x.co>, David Wei <dw@...idwei.uk>
Subject: [PATCH net v3 2/4] llc: Improve setsockopt() handling of malformed
 user input

copy_from_sockptr() is used incorrectly: return value is the number of
bytes that could not be copied. Since it's deprecated, switch to
copy_safe_from_sockptr().

Note: Keeping the `optlen != sizeof(int)` check as copy_safe_from_sockptr()
by itself would also accept optlen > sizeof(int). Which would allow a more
lenient handling of inputs.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Suggested-by: David Wei <dw@...idwei.uk>
Signed-off-by: Michal Luczaj <mhal@...x.co>
---
 net/llc/af_llc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c
index 4eb52add7103b0f83d6fe7318abf1d1af533d254..0259cde394ba09795a6bf0d44c4ea6767e200aea 100644
--- a/net/llc/af_llc.c
+++ b/net/llc/af_llc.c
@@ -1098,7 +1098,7 @@ static int llc_ui_setsockopt(struct socket *sock, int level, int optname,
 	lock_sock(sk);
 	if (unlikely(level != SOL_LLC || optlen != sizeof(int)))
 		goto out;
-	rc = copy_from_sockptr(&opt, optval, sizeof(opt));
+	rc = copy_safe_from_sockptr(&opt, sizeof(opt), optval, optlen);
 	if (rc)
 		goto out;
 	rc = -EINVAL;

-- 
2.46.2