linux-kernel - [PATCH] io_uring/uring_cmd: add missing READ

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Message-Id: <20250121-uring-sockcmd-fix-v1-1-add742802a29@google.com>
Date: Tue, 21 Jan 2025 17:09:59 +0100
From: Jann Horn <jannh@...gle.com>
To: Jens Axboe <axboe@...nel.dk>, Pavel Begunkov <asml.silence@...il.com>
Cc: io-uring@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Jann Horn <jannh@...gle.com>
Subject: [PATCH] io_uring/uring_cmd: add missing READ_ONCE() on shared
 memory read

cmd->sqe seems to point to shared memory here; so values should only be
read from it with READ_ONCE(). To ensure that the compiler won't generate
code that assumes the value in memory will stay constant, add a
READ_ONCE().
The callees io_uring_cmd_getsockopt() and io_uring_cmd_setsockopt() already
do this correctly.

Signed-off-by: Jann Horn <jannh@...gle.com>
---
 io_uring/uring_cmd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index fc94c465a9850d4ed9df0cd26fcd6523657a2854..f4397bd66283d5939b60e7fa0a12bd7426322b9f 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -350,7 +350,7 @@ int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
 	if (!prot || !prot->ioctl)
 		return -EOPNOTSUPP;
 
-	switch (cmd->sqe->cmd_op) {
+	switch (READ_ONCE(cmd->sqe->cmd_op)) {
 	case SOCKET_URING_OP_SIOCINQ:
 		ret = prot->ioctl(sk, SIOCINQ, &arg);
 		if (ret)

---
base-commit: 95ec54a420b8f445e04a7ca0ea8deb72c51fe1d3
change-id: 20250121-uring-sockcmd-fix-75b73e5b9750

-- 
Jann Horn <jannh@...gle.com>