linux-kernel - [PATCH 1/1] btrfs: ioctl: don't free iov when -EAGAIN in uring encoded read

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Message-ID: <20250319112401.22316-1-sidong.yang@furiosa.ai>
Date: Wed, 19 Mar 2025 11:24:01 +0000
From: Sidong Yang <sidong.yang@...iosa.ai>
To: Josef Bacik <josef@...icpanda.com>,
	David Sterba <dsterba@...e.com>
Cc: Mark Harmstone <maharmstone@...a.com>,
	linux-btrfs@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Sidong Yang <sidong.yang@...iosa.ai>
Subject: [PATCH 1/1] btrfs: ioctl: don't free iov when -EAGAIN in uring encoded read

This patch fixes a bug on encoded_read. In btrfs_uring_encoded_read(),
btrfs_encoded_read could return -EAGAIN when receiving requests concurrently.
And data->iov goes to out_free and it freed and return -EAGAIN. io-uring
subsystem would call it again and it doesn't reset data. And data->iov
freed and iov_iter reference it. iov_iter would be used in
btrfs_uring_read_finished() and could be raise memory bug.

Signed-off-by: Sidong Yang <sidong.yang@...iosa.ai>
---
 fs/btrfs/ioctl.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index c44e6ce6e5f5..b556db9e7cc4 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4924,6 +4924,9 @@ static int btrfs_uring_encoded_read(struct io_uring_cmd *cmd, unsigned int issue
 
 	ret = btrfs_encoded_read(&kiocb, &data->iter, &data->args, &cached_state,
 				 &disk_bytenr, &disk_io_size);
+
+	if (ret == -EAGAIN)
+		goto out_acct;
 	if (ret < 0 && ret != -EIOCBQUEUED)
 		goto out_free;
 
-- 
2.43.0