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[2603:8081:140c:1a00:8baa:bb83:cd49:4ca4]) by smtp.gmail.com with ESMTPSA id w11sm3722564otg.58.2021.01.25.13.16.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Jan 2021 13:16:45 -0800 (PST) From: Bob Pearson X-Google-Original-From: Bob Pearson To: jgg@nvidia.com, zyjzyj2000@gmail.com, linux-rdma@vger.kernel.org Cc: Bob Pearson , syzbot+ec2fd72374785d0e558e@syzkaller.appspotmail.com Subject: [PATCH for-next v3 1/6] RDMA/rxe: Fix bug in rxe_alloc Date: Mon, 25 Jan 2021 15:16:36 -0600 Message-Id: <20210125211641.2694-2-rpearson@hpe.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210125211641.2694-1-rpearson@hpe.com> References: <20210125211641.2694-1-rpearson@hpe.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org [v1] A recent patch which added an 'unlocked' version of rxe_alloc introduced a bug causing kzalloc(..., GFP_KERNEL) to be called while holding a spin lock. This patch corrects that error. rxe_alloc_nl() should always be called while holding the pool->pool_lock so the 2nd argument to kzalloc there should be GFP_ATOMIC. rxe_alloc() prior to the change only locked the code around checking that pool->state is RXE_POOL_STATE_VALID to avoid races between working threads and a thread shutting down the rxe driver. This patch reverts rxe_alloc() to this behavior so the lock is not held when kzalloc() is called. Reported-by: syzbot+ec2fd72374785d0e558e@syzkaller.appspotmail.com Fixes: 3853c35e243d ("RDMA/rxe: Add unlocked versions of pool APIs") Signed-off-by: Bob Pearson --- drivers/infiniband/sw/rxe/rxe_pool.c | 41 ++++++++++++++++++++++++---- 1 file changed, 35 insertions(+), 6 deletions(-) diff --git a/drivers/infiniband/sw/rxe/rxe_pool.c b/drivers/infiniband/sw/rxe/rxe_pool.c index d26730eec720..cfcd55175572 100644 --- a/drivers/infiniband/sw/rxe/rxe_pool.c +++ b/drivers/infiniband/sw/rxe/rxe_pool.c @@ -343,8 +343,6 @@ void *rxe_alloc_nl(struct rxe_pool *pool) struct rxe_pool_entry *elem; u8 *obj; - might_sleep_if(!(pool->flags & RXE_POOL_ATOMIC)); - if (pool->state != RXE_POOL_STATE_VALID) return NULL; @@ -356,8 +354,7 @@ void *rxe_alloc_nl(struct rxe_pool *pool) if (atomic_inc_return(&pool->num_elem) > pool->max_elem) goto out_cnt; - obj = kzalloc(info->size, (pool->flags & RXE_POOL_ATOMIC) ? - GFP_ATOMIC : GFP_KERNEL); + obj = kzalloc(info->size, GFP_ATOMIC); if (!obj) goto out_cnt; @@ -378,14 +375,46 @@ void *rxe_alloc_nl(struct rxe_pool *pool) void *rxe_alloc(struct rxe_pool *pool) { - u8 *obj; unsigned long flags; + struct rxe_type_info *info = &rxe_type_info[pool->type]; + struct rxe_pool_entry *elem; + u8 *obj; + + might_sleep_if(!(pool->flags & RXE_POOL_ATOMIC)); read_lock_irqsave(&pool->pool_lock, flags); - obj = rxe_alloc_nl(pool); + if (pool->state != RXE_POOL_STATE_VALID) { + read_unlock_irqrestore(&pool->pool_lock, flags); + return NULL; + } + + kref_get(&pool->ref_cnt); read_unlock_irqrestore(&pool->pool_lock, flags); + if (!ib_device_try_get(&pool->rxe->ib_dev)) + goto out_put_pool; + + if (atomic_inc_return(&pool->num_elem) > pool->max_elem) + goto out_cnt; + + obj = kzalloc(info->size, (pool->flags & RXE_POOL_ATOMIC) ? + GFP_ATOMIC : GFP_KERNEL); + if (!obj) + goto out_cnt; + + elem = (struct rxe_pool_entry *)(obj + info->elem_offset); + + elem->pool = pool; + kref_init(&elem->ref_cnt); + return obj; + +out_cnt: + atomic_dec(&pool->num_elem); + ib_device_put(&pool->rxe->ib_dev); +out_put_pool: + rxe_pool_put(pool); + return NULL; } int __rxe_add_to_pool(struct rxe_pool *pool, struct rxe_pool_entry *elem) -- 2.27.0