From 75321b50a37a5ba612125a04bfc9e43e3da5b305 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 9 Apr 2018 14:57:56 +0200 Subject: [PATCH] aio: sanitize ki_list handling Instead of handcoded non-null checks always initialize ki_list to an empty list and use list_empty / list_empty_careful on it. While we're at it also error out on a double call to kiocb_set_cancel_fn instead of ignoring it. Signed-off-by: Christoph Hellwig Acked-by: Jeff Moyer Reviewed-by: Greg Kroah-Hartman Reviewed-by: Darrick J. Wong --- fs/aio.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index 7c1855afd723..18507743757a 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -553,13 +553,12 @@ void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel) struct kioctx *ctx = req->ki_ctx; unsigned long flags; + if (WARN_ON_ONCE(!list_empty(&req->ki_list))) + return; + spin_lock_irqsave(&ctx->ctx_lock, flags); - - if (!req->ki_list.next) - list_add(&req->ki_list, &ctx->active_reqs); - + list_add_tail(&req->ki_list, &ctx->active_reqs); req->ki_cancel = cancel; - spin_unlock_irqrestore(&ctx->ctx_lock, flags); } EXPORT_SYMBOL(kiocb_set_cancel_fn); @@ -1039,7 +1038,7 @@ static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx) goto out_put; percpu_ref_get(&ctx->reqs); - + INIT_LIST_HEAD(&req->ki_list); req->ki_ctx = ctx; return req; out_put: @@ -1107,7 +1106,7 @@ static void aio_complete(struct kiocb *kiocb, long res, long res2) file_end_write(file); } - if (iocb->ki_list.next) { + if (!list_empty_careful(&iocb->ki_list)) { unsigned long flags; spin_lock_irqsave(&ctx->ctx_lock, flags);