lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Mon, 1 Oct 2018 00:40:33 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Jann Horn <jannh@...gle.com>, Jason Gunthorpe <jgg@...lanox.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL 4.9 07/26] RDMA/ucma: check fd type in
 ucma_migrate_id()

From: Jann Horn <jannh@...gle.com>

[ Upstream commit 0d23ba6034b9cf48b8918404367506da3e4b3ee5 ]

The current code grabs the private_data of whatever file descriptor
userspace has supplied and implicitly casts it to a `struct ucma_file *`,
potentially causing a type confusion.

This is probably fine in practice because the pointer is only used for
comparisons, it is never actually dereferenced; and even in the
comparisons, it is unlikely that a file from another filesystem would have
a ->private_data pointer that happens to also be valid in this context.
But ->private_data is not always guaranteed to be a valid pointer to an
object owned by the file's filesystem; for example, some filesystems just
cram numbers in there.

Check the type of the supplied file descriptor to be safe, analogous to how
other places in the kernel do it.

Fixes: 88314e4dda1e ("RDMA/cma: add support for rdma_migrate_id()")
Signed-off-by: Jann Horn <jannh@...gle.com>
Signed-off-by: Jason Gunthorpe <jgg@...lanox.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 drivers/infiniband/core/ucma.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index 3bef6d4ffe6f..0fd0d82f80d2 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -124,6 +124,8 @@ static DEFINE_MUTEX(mut);
 static DEFINE_IDR(ctx_idr);
 static DEFINE_IDR(multicast_idr);
 
+static const struct file_operations ucma_fops;
+
 static inline struct ucma_context *_ucma_find_context(int id,
 						      struct ucma_file *file)
 {
@@ -1545,6 +1547,10 @@ static ssize_t ucma_migrate_id(struct ucma_file *new_file,
 	f = fdget(cmd.fd);
 	if (!f.file)
 		return -ENOENT;
+	if (f.file->f_op != &ucma_fops) {
+		ret = -EINVAL;
+		goto file_put;
+	}
 
 	/* Validate current fd and prevent destruction of id. */
 	ctx = ucma_get_ctx(f.file->private_data, cmd.id);
-- 
2.17.1

Powered by blists - more mailing lists