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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org,
        syzbot+a38b0e9f694c379ca7ce@syzkaller.appspotmail.com,
        "Doug Ledford" <dledford@redhat.com>,
        "Leon Romanovsky" <leonro@mellanox.com>
Date:   Thu, 07 Jun 2018 15:05:21 +0100
Message-ID: <lsq.1528380321.656879929@decadent.org.uk>
Subject: [PATCH 3.16 331/410] RDMA/ucma: Limit possible option size
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3.16.57-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Leon Romanovsky <leonro@mellanox.com>

commit 6a21dfc0d0db7b7e0acedce67ca533a6eb19283c upstream.

Users of ucma are supposed to provide size of option level,
in most paths it is supposed to be equal to u8 or u16, but
it is not the case for the IB path record, where it can be
multiple of struct ib_path_rec_data.

This patch takes simplest possible approach and prevents providing
values more than possible to allocate.

Reported-by: syzbot+a38b0e9f694c379ca7ce@syzkaller.appspotmail.com
Fixes: 7ce86409adcd ("RDMA/ucma: Allow user space to set service type")
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 drivers/infiniband/core/ucma.c | 3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -1187,6 +1187,9 @@ static ssize_t ucma_set_option(struct uc
 	if (IS_ERR(ctx))
 		return PTR_ERR(ctx);
 
+	if (unlikely(cmd.optval > KMALLOC_MAX_SIZE))
+		return -EINVAL;
+
 	optval = memdup_user((void __user *) (unsigned long) cmd.optval,
 			     cmd.optlen);
 	if (IS_ERR(optval)) {