From 961ebd120565cb60cebe21cb634fbc456022db4a Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Mon, 4 Mar 2024 15:57:15 -0800 Subject: [PATCH] fs/aio: Check IOCB_AIO_RW before the struct aio_kiocb conversion 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 Cc: Benjamin LaHaise Cc: Eric Biggers Cc: Christoph Hellwig Cc: Avi Kivity Cc: Sandeep Dhavale Cc: Jens Axboe Cc: Greg Kroah-Hartman Cc: Kent Overstreet 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 Link: https://lore.kernel.org/r/20240304235715.3790858-1-bvanassche@acm.org Reviewed-by: Jens Axboe Reviewed-by: Eric Biggers Signed-off-by: Christian Brauner --- fs/aio.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index da18dbcfcb22..9cdaa2faa536 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -589,8 +589,8 @@ static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events) 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; /* @@ -600,9 +600,13 @@ void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel) 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;