lkml.org 
[lkml]   [2018]   [Jul]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4.17 095/220] IB/uverbs: Fix ordering of ucontext check in ib_uverbs_write
Date
4.17-stable review patch.  If anyone has any objections, please let me know.

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

From: Jason Gunthorpe <jgg@mellanox.com>

commit 1eb9364ce81d9445ad6f9d44921a91d2a6597156 upstream.

During disassociation the ucontext will become NULL, however due to how
the SRCU locking works the ucontext must only be examined after looking
at the ib_dev, which governs the RCU control flow.

With the wrong ordering userspace will see EINVAL instead of EIO for a
disassociated uverbs FD, which breaks rdma-core.

Cc: stable@vger.kernel.org
Fixes: 491d5c6a3023 ("RDMA/uverbs: Move uncontext check before SRCU read lock")
Reported-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/infiniband/core/uverbs_main.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)

--- a/drivers/infiniband/core/uverbs_main.c
+++ b/drivers/infiniband/core/uverbs_main.c
@@ -734,10 +734,6 @@ static ssize_t ib_uverbs_write(struct fi
if (ret)
return ret;

- if (!file->ucontext &&
- (command != IB_USER_VERBS_CMD_GET_CONTEXT || extended))
- return -EINVAL;
-
if (extended) {
if (count < (sizeof(hdr) + sizeof(ex_hdr)))
return -EINVAL;
@@ -757,6 +753,16 @@ static ssize_t ib_uverbs_write(struct fi
goto out;
}

+ /*
+ * Must be after the ib_dev check, as once the RCU clears ib_dev ==
+ * NULL means ucontext == NULL
+ */
+ if (!file->ucontext &&
+ (command != IB_USER_VERBS_CMD_GET_CONTEXT || extended)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
if (!verify_command_mask(ib_dev, command, extended)) {
ret = -EOPNOTSUPP;
goto out;

\
 
 \ /
  Last update: 2018-07-01 19:11    [W:0.658 / U:26.296 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site