io_uring: always grab file table for deferred statx

stable inclusion
from stable-v5.10.118
commit 3c48558be571e01f67e65edcf03193484eeb2b79
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5L686

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3c48558be571e01f67e65edcf03193484eeb2b79

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

Lee reports that there's a use-after-free of the process file table.
There's an assumption that we don't need the file table for some
variants of statx invocation, but that turns out to be false and we
end up with not grabbing a reference for the request even if the
deferred execution uses it.

Get rid of the REQ_F_NO_FILE_TABLE optimization for statx, and always
grab that reference.

This issues doesn't exist upstream since the native workers got
introduced with 5.12.

Link: https://lore.kernel.org/io-uring/YoOJ%2FT4QRKC+fAZE@google.com/Reported-by: NLee Jones <lee.jones@linaro.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>

fs/io_uring.c

@@ -4263,12 +4263,8 @@ static int io_statx(struct io_kiocb *req, bool force_nonblock)
 	struct io_statx *ctx = &req->statx;
 	int ret;
 
-	if (force_nonblock) {
-		/* only need file table for an actual valid fd */
-		if (ctx->dfd == -1 || ctx->dfd == AT_FDCWD)
-			req->flags |= REQ_F_NO_FILE_TABLE;
+	if (force_nonblock)
 		return -EAGAIN;
-	}
 
 	ret = do_statx(ctx->dfd, ctx->filename, ctx->flags, ctx->mask,
 		       ctx->buffer);