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authorJens Axboe <axboe@kernel.dk>2020-12-29 10:50:46 -0700
committerJens Axboe <axboe@kernel.dk>2020-12-29 11:00:36 -0700
commit77788775c7132a8d93c6930ab1bd84fc743c7cb7 (patch)
tree2f5da76650d3d77b40923c6b632d23b8e15a4837
parent5c8fe583cce542aa0b84adc939ce85293de36e5e (diff)
downloadlinux-stericsson-77788775c7132a8d93c6930ab1bd84fc743c7cb7.tar.gz
io_uring: don't assume mm is constant across submits
If we COW the identity, we assume that ->mm never changes. But this isn't true of multiple processes end up sharing the ring. Hence treat id->mm like like any other process compontent when it comes to the identity mapping. This is pretty trivial, just moving the existing grab into io_grab_identity(), and including a check for the match. Cc: stable@vger.kernel.org # 5.10 Fixes: 1e6fa5216a0e ("io_uring: COW io_identity on mismatch") Reported-by: Christian Brauner <christian.brauner@ubuntu.com>: Tested-by: Christian Brauner <christian.brauner@ubuntu.com>: Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--fs/io_uring.c14
1 files changed, 7 insertions, 7 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 7e35283fc0b1..eb4620ff638e 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1501,6 +1501,13 @@ static bool io_grab_identity(struct io_kiocb *req)
spin_unlock_irq(&ctx->inflight_lock);
req->work.flags |= IO_WQ_WORK_FILES;
}
+ if (!(req->work.flags & IO_WQ_WORK_MM) &&
+ (def->work_flags & IO_WQ_WORK_MM)) {
+ if (id->mm != current->mm)
+ return false;
+ mmgrab(id->mm);
+ req->work.flags |= IO_WQ_WORK_MM;
+ }
return true;
}
@@ -1525,13 +1532,6 @@ static void io_prep_async_work(struct io_kiocb *req)
req->work.flags |= IO_WQ_WORK_UNBOUND;
}
- /* ->mm can never change on us */
- if (!(req->work.flags & IO_WQ_WORK_MM) &&
- (def->work_flags & IO_WQ_WORK_MM)) {
- mmgrab(id->mm);
- req->work.flags |= IO_WQ_WORK_MM;
- }
-
/* if we fail grabbing identity, we must COW, regrab, and retry */
if (io_grab_identity(req))
return;