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From:   Yang Yingliang <yangyingliang@huawei.com>
To:     <io-uring@vger.kernel.org>, <linux-kernel@vger.kernel.org>
CC:     <axboe@kernel.dk>
Subject: [PATCH] io_uring: fix memleak in io_sqe_files_register()
Date:   Fri, 10 Jul 2020 14:14:20 +0000
Message-ID: <20200710141420.3987063-1-yangyingliang@huawei.com>
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I got a memleak report when doing some fuzz test:

BUG: memory leak
unreferenced object 0x607eeac06e78 (size 8):
  comm "test", pid 295, jiffies 4294735835 (age 31.745s)
  hex dump (first 8 bytes):
    00 00 00 00 00 00 00 00                          ........
  backtrace:
    [<00000000932632e6>] percpu_ref_init+0x2a/0x1b0
    [<0000000092ddb796>] __io_uring_register+0x111d/0x22a0
    [<00000000eadd6c77>] __x64_sys_io_uring_register+0x17b/0x480
    [<00000000591b89a6>] do_syscall_64+0x56/0xa0
    [<00000000864a281d>] entry_SYSCALL_64_after_hwframe+0x44/0xa9


Call percpu_ref_exit() on error path to avoid
refcount memleak.

Fixes: 05f3fb3c5397 ("io_uring: avoid ring quiesce for fixed file set unregister and update")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
 fs/io_uring.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index d37d7ea5ebe5..ea81be3c14af 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6693,6 +6693,7 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
 		for (i = 0; i < nr_tables; i++)
 			kfree(ctx->file_data->table[i].files);
 
+		percpu_ref_exit(&ctx->file_data->refs);
 		kfree(ctx->file_data->table);
 		kfree(ctx->file_data);
 		ctx->file_data = NULL;
-- 
2.25.1