f4a192cd7b
[ Upstream commit 055ca83559912f2cfd91c9441427bac4caf3c74e ] When you try to splice between a normal pipe and a notification pipe, get_pipe_info(..., true) fails, so splice() falls back to treating the notification pipe like a normal pipe - so we end up in iter_file_splice_write(), which first locks the input pipe, then calls vfs_iter_write(), which locks the output pipe. Lockdep complains about that, because we're taking a pipe lock while already holding another pipe lock. I think this probably (?) can't actually lead to deadlocks, since you'd need another way to nest locking a normal pipe into locking a watch_queue pipe, but the lockdep annotations don't make that clear. Bail out earlier in pipe_write() for notification pipes, before taking the pipe lock. Reported-and-tested-by: <syzbot+011e4ea1da6692cf881c@syzkaller.appspotmail.com> Closes: https://syzkaller.appspot.com/bug?extid=011e4ea1da6692cf881c Fixes: c73be61cede5 ("pipe: Add general notification queue support") Signed-off-by: Jann Horn <jannh@google.com> Link: https://lore.kernel.org/r/20231124150822.2121798-1-jannh@google.com Signed-off-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.