5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Bart Van Assche bvanassche@acm.org
commit 961ebd120565cb60cebe21cb634fbc456022db4a upstream.
The first kiocb_set_cancel_fn() argument may point at a struct kiocb that is not embedded inside struct aio_kiocb. With the current code, depending on the compiler, the req->ki_ctx read happens either before the IOCB_AIO_RW test or after that test. Move the req->ki_ctx read such that it is guaranteed that the IOCB_AIO_RW test happens first.
Reported-by: Eric Biggers ebiggers@kernel.org Cc: Benjamin LaHaise ben@communityfibre.ca Cc: Eric Biggers ebiggers@google.com Cc: Christoph Hellwig hch@lst.de Cc: Avi Kivity avi@scylladb.com Cc: Sandeep Dhavale dhavale@google.com Cc: Jens Axboe axboe@kernel.dk Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Kent Overstreet kent.overstreet@linux.dev Cc: stable@vger.kernel.org Fixes: b820de741ae4 ("fs/aio: Restrict kiocb_set_cancel_fn() to I/O submitted via libaio") Signed-off-by: Bart Van Assche bvanassche@acm.org Link: https://lore.kernel.org/r/20240304235715.3790858-1-bvanassche@acm.org Reviewed-by: Jens Axboe axboe@kernel.dk Reviewed-by: Eric Biggers ebiggers@google.com Signed-off-by: Christian Brauner brauner@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/aio.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
--- a/fs/aio.c +++ b/fs/aio.c @@ -566,8 +566,8 @@ static int aio_setup_ring(struct kioctx
void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel) { - struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, rw); - struct kioctx *ctx = req->ki_ctx; + struct aio_kiocb *req; + struct kioctx *ctx; unsigned long flags;
/* @@ -577,9 +577,13 @@ void kiocb_set_cancel_fn(struct kiocb *i if (!(iocb->ki_flags & IOCB_AIO_RW)) return;
+ req = container_of(iocb, struct aio_kiocb, rw); + if (WARN_ON_ONCE(!list_empty(&req->ki_list))) return;
+ ctx = req->ki_ctx; + spin_lock_irqsave(&ctx->ctx_lock, flags); list_add_tail(&req->ki_list, &ctx->active_reqs); req->ki_cancel = cancel;