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| author |   Jason Gunthorpe <jgunthorpe@obsidianresearch.com> | 2015-08-04 17:13:32 -0600 |
|---|---|---|
| committer |   Doug Ledford <dledford@redhat.com> | 2015-08-28 22:54:48 -0400 |
| commit | 7e967fd0b84a843b2475acc67a5a8df138c5f5c0 (patch) | |
| tree | 3b3fce60c75058d1d5ce891b6c1dc7efca549d6f /drivers/infiniband/core/ucma.c | |
| parent | iw_cxgb4: set the default MPA version to 2 (diff) | |
| download | linux-dev-7e967fd0b84a843b2475acc67a5a8df138c5f5c0.tar.xz linux-dev-7e967fd0b84a843b2475acc67a5a8df138c5f5c0.zip | |
IB/ucma: Fix theoretical user triggered use-after-free
Something like this:
CPU A CPU B
Acked-by: Sean Hefty <sean.hefty@intel.com>
======================== ================================
ucma_destroy_id()
wait_for_completion()
.. anything
ucma_put_ctx()
complete()
.. continues ...
ucma_leave_multicast()
mutex_lock(mut)
atomic_inc(ctx->ref)
mutex_unlock(mut)
ucma_free_ctx()
ucma_cleanup_multicast()
mutex_lock(mut)
kfree(mc)
rdma_leave_multicast(mc->ctx->cm_id,..
Fix it by latching the ref at 0. Once it goes to 0 mc and ctx cannot
leave the mutex(mut) protection.
The other atomic_inc in ucma_get_ctx is OK because mutex(mut) protects
it from racing with ucma_destroy_id.
Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Acked-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Diffstat (limited to 'drivers/infiniband/core/ucma.c')
| -rw-r--r-- | drivers/infiniband/core/ucma.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c index 29b21213ea75..acac9eafdbf6 100644 --- a/drivers/infiniband/core/ucma.c +++ b/drivers/infiniband/core/ucma.c @@ -1321,10 +1321,10 @@ static ssize_t ucma_leave_multicast(struct ucma_file *file, mc = ERR_PTR(-ENOENT); else if (mc->ctx->file != file) mc = ERR_PTR(-EINVAL); - else { + else if (!atomic_inc_not_zero(&mc->ctx->ref)) + mc = ERR_PTR(-ENXIO); + else idr_remove(&multicast_idr, mc->id); - atomic_inc(&mc->ctx->ref); - } mutex_unlock(&mut); if (IS_ERR(mc)) { |