[PATCH 6.1 188/195] fs/aio: Restrict kiocb_set_cancel_fn() to I/O submitted via libaio

Greg Kroah-Hartman
2024-02-27T14:21:00Z

From: Bart Van Assche <bvanassche@acm.org>

commit b820de741ae48ccf50dd95e297889c286ff4f760 upstream.

If kiocb_set_cancel_fn() is called for I/O submitted via io_uring, the
following kernel warning appears:

WARNING: CPU: 3 PID: 368 at fs/aio.c:598 kiocb_set_cancel_fn+0x9c/0xa8
Call trace:
kiocb_set_cancel_fn+0x9c/0xa8
ffs_epfile_read_iter+0x144/0x1d0
io_read+0x19c/0x498
io_issue_sqe+0x118/0x27c
io_submit_sqes+0x25c/0x5fc
__arm64_sys_io_uring_enter+0x104/0xab0
invoke_syscall+0x58/0x11c
el0_svc_common+0xb4/0xf4
do_el0_svc+0x2c/0xb0
el0_svc+0x2c/0xa4
el0t_64_sync_handler+0x68/0xb4
el0t_64_sync+0x1a4/0x1a8

Fix this by setting the IOCB_AIO_RW flag for read and write I/O that is
submitted by libaio.

Suggested-by: Jens Axboe <axboe@kernel.dk>
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
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240215204739.2677806-2-bvanassche@acm.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/aio.c | 9 ++++++++-
include/linux/fs.h | 2 ++
2 files changed, 10 insertions(+), 1 deletion(-)

--- a/fs/aio.c
+++ b/fs/aio.c
@@ -595,6 +595,13 @@ void kiocb_set_cancel_fn(struct kiocb *i
struct kioctx *ctx = req->ki_ctx;
unsigned long flags;

+ /*
+ * kiocb didn't come from aio or is neither a read nor a write, hence
+ * ignore it.
+ */
+ if (!(iocb->ki_flags & IOCB_AIO_RW))
+ return;
+
if (WARN_ON_ONCE(!list_empty(&req->ki_list)))
return;

@@ -1476,7 +1483,7 @@ static int aio_prep_rw(struct kiocb *req
req->ki_complete = aio_complete_rw;
req->private = NULL;
req->ki_pos = iocb->aio_offset;
- req->ki_flags = req->ki_filp->f_iocb_flags;
+ req->ki_flags = req->ki_filp->f_iocb_flags | IOCB_AIO_RW;
if (iocb->aio_flags & IOCB_FLAG_RESFD)
req->ki_flags |= IOCB_EVENTFD;
if (iocb->aio_flags & IOCB_FLAG_IOPRIO) {
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -337,6 +337,8 @@ enum rw_hint {
#define IOCB_NOIO (1 << 20)
/* can use bio alloc cache */
#define IOCB_ALLOC_CACHE (1 << 21)
+/* kiocb is a read or write operation submitted by fs/aio.c. */
+#define IOCB_AIO_RW (1 << 23)

struct kiocb {
struct file *ki_filp;