[PATCH] unix_diag: fix incorrect sign extension in unix_lookup_by_ino

The value passed by unix_diag_get_exact to unix_lookup_by_ino has type
__u32, but unix_lookup_by_ino's argument ino has type int, which is not
a problem yet.
However, when ino is compared with sock_i_ino return value of type
unsigned long, ino is sign extended to signed long, and this results
to incorrect comparison on 64-bit architectures for inode numbers
greater than INT_MAX.

This bug was found by strace test suite.

Signed-off-by: Dmitry V. Levin <redacted>
Cc: <redacted>
---
 net/unix/diag.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/unix/diag.c b/net/unix/diag.c
index c512f64..4d96797 100644
--- a/net/unix/diag.c
+++ b/net/unix/diag.c

@@ -220,23 +220,23 @@ done:
 	return skb->len;
 }
 
-static struct sock *unix_lookup_by_ino(int ino)
+static struct sock *unix_lookup_by_ino(unsigned int ino)
 {
 	int i;
 	struct sock *sk;
 
 	spin_lock(&unix_table_lock);
 	for (i = 0; i < ARRAY_SIZE(unix_socket_table); i++) {
 		sk_for_each(sk, &unix_socket_table[i])
 			if (ino == sock_i_ino(sk)) {
 				sock_hold(sk);
 				spin_unlock(&unix_table_lock);
 
 				return sk;
 			}
 	}
 
 	spin_unlock(&unix_table_lock);
 	return NULL;
 }
 

-- 
ldv

On Thu, Feb 18, 2016 at 5:27 PM, Dmitry V. Levin [off-list ref] wrote:

The value passed by unix_diag_get_exact to unix_lookup_by_ino has type
__u32, but unix_lookup_by_ino's argument ino has type int, which is not
a problem yet.
However, when ino is compared with sock_i_ino return value of type
unsigned long, ino is sign extended to signed long, and this results
to incorrect comparison on 64-bit architectures for inode numbers
greater than INT_MAX.

This bug was found by strace test suite.

Signed-off-by: Dmitry V. Levin <redacted>
Cc: <redacted>

Fixes: 5d3cae8bc39d ("unix_diag: Dumping exact socket core")
Acked-by: Cong Wang <redacted>

Thanks.

From: Cong Wang <redacted>
Date: Fri, 19 Feb 2016 16:21:14 -0800

On Thu, Feb 18, 2016 at 5:27 PM, Dmitry V. Levin [off-list ref] wrote:

quoted

The value passed by unix_diag_get_exact to unix_lookup_by_ino has type
__u32, but unix_lookup_by_ino's argument ino has type int, which is not
a problem yet.
However, when ino is compared with sock_i_ino return value of type
unsigned long, ino is sign extended to signed long, and this results
to incorrect comparison on 64-bit architectures for inode numbers
greater than INT_MAX.

This bug was found by strace test suite.

Signed-off-by: Dmitry V. Levin <redacted>
Cc: <redacted>

Fixes: 5d3cae8bc39d ("unix_diag: Dumping exact socket core")
Acked-by: Cong Wang <redacted>

Applied and queued up for -stable.