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b=DEEX4qDz+fc+kgDAW7/JviDpIk5mPt0fAGVP7azHnNTmmjo2ZkJCS8asv7W1wJrSa CZrpUDEmwtcxLKXenhRekY9I+eFJnFpbL6DuXyXzhisRzcpkhBwumlLbNmQaWhtX8J schw36UVg2Hci5+e1wHOgoCOdDw0egQCLdeQeWFY= Date: Wed, 16 Oct 2024 15:16:36 -0700 From: Andrew Morton To: Jeongjun Park Cc: hughd@google.com, yuzhao@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, syzbot , stable@vger.kernel.org Subject: Re: [PATCH RESEND] mm: shmem: fix data-race in shmem_getattr() Message-Id: <20241016151636.7e2184ca7467a0f8f90d940c@linux-foundation.org> In-Reply-To: References: <20240922080838.15184-1-aha310510@gmail.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 8B19A4000D X-Stat-Signature: 4bs1mry8hmnpa8rd5tb1dbxqzd3yfu5s X-HE-Tag: 1729116986-642657 X-HE-Meta: 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 jlPrH1NL WKcpeEIqpXDyB3F0perRQjYvS+Nm/9/mPOYADhD5Da4hMIcjyyHoRHCiFRVxqYWPTgQ8DId8dkcs0BqPY6HFHaLUZzKQ5568TuVXln40tOj0v+N47n0vWw0wAAmjiSqnuLGiYHcNt9hWuqBfiuS8oT6G9dXihaNOpHRzz2N+WlSKzQi5fJgWNjk4hLDMEPLHoE5nkIg5mIpZ+hjTzmAXbK1ag5DnDnIZTCSDbtERe2f+TyCZbUOo28qgLo1vRk+eUWzN9aemjSoyhdSZ7kq+1Igr2asqQ6GIT6hK4EzRgj0ZH/ZtZ1Y6k7+TLhvqRJ5wv02kHZVvLXHOW/4uthLEByyMSVp0PqezOpytX3KYfWiUoJtwxDcu6pwZrBA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 16 Oct 2024 23:12:43 +0900 Jeongjun Park wrote: > > Therefore, when calling generic_fillattr() from shmem_getattr(), it is > > appropriate to protect the inode using inode_lock_shared() and > > inode_unlock_shared() to prevent data-race. > > > > Cc: stable@vger.kernel.org > > I think this patch should be applied from next rc version and also stable > version. When calling generic_fillattr(), if you don't hold read lock, > data-race will occur in inode member variables, which can cause unexpected > behavior. This problem is also present in several stable versions, so I think > it should be fixed as soon as possible. OK, thanks, I added the cc:stable amd moved this into the mm-hotfixes pile for a 6.12-rcX merge.