From: Jens Axboe <axboe@xxxxxxxxx>
[ upstream commmit e2c0cb7c0cc72939b61a7efee376206725796625 ]
The previous commit:
1bc84c40088 ("io_uring: remove poll entry from list when canceling all")
removed a potential overflow condition for the poll references. They
are currently limited to 20-bits, even if we have 31-bits available. The
upper bit is used to mark for cancelation.
Bump the poll ref space to 31-bits, making that kind of situation much
harder to trigger in general. We'll separately add overflow checking
and handling.
Fixes: aa43477b0402 ("io_uring: poll rework")
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
[pavel: backport]
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/io_uring.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -5314,7 +5314,7 @@ struct io_poll_table {
};
#define IO_POLL_CANCEL_FLAG BIT(31)
-#define IO_POLL_REF_MASK ((1u << 20)-1)
+#define IO_POLL_REF_MASK GENMASK(30, 0)
/*
* If refs part of ->poll_refs (see IO_POLL_REF_MASK) is 0, it's free. We can
