linux-kernel - [PATCH][next] io_uring: Fix a read of ununitialized pointer tctx

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Message-Id: <20210903113535.11257-1-colin.king@canonical.com>
Date:   Fri,  3 Sep 2021 12:35:35 +0100
From:   Colin King <colin.king@...onical.com>
To:     Jens Axboe <axboe@...nel.dk>,
        Pavel Begunkov <asml.silence@...il.com>,
        io-uring@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH][next] io_uring: Fix a read of ununitialized pointer tctx

From: Colin Ian King <colin.king@...onical.com>

In the unlikely case where ctx->flags & IORING_SETUP_SQPOLL is true
and sqd is NULL the pointer tctx is not assigned a valid value and
can contain a garbage value when it is dereferenced. Fix this by
initializing it to NULL.

Addresses-Coverity: ("Uninitialized pointer read")
Fixes: 9e30726065ea ("io_uring: ensure IORING_REGISTER_IOWQ_MAX_WORKERS works with SQPOLL")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 fs/io_uring.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 132dd38e89ce..843362bebd8c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -10525,7 +10525,7 @@ static int io_register_iowq_max_workers(struct io_ring_ctx *ctx,
 					void __user *arg)
 {
 	struct io_sq_data *sqd = NULL;
-	struct io_uring_task *tctx;
+	struct io_uring_task *tctx = NULL;
 	__u32 new_count[2];
 	int i, ret;
 
-- 
2.32.0