diff options
| author | Jens Axboe <axboe@kernel.dk> | 2019-10-28 09:15:33 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2019-10-28 09:15:33 -0600 |
| commit | 044c1ab399afbe9f2ebef49a3204ef1509826dc7 (patch) | |
| tree | 25b1ccdca5d8d48a99f2370144f797f56754866a /fs | |
| parent | 7b20238d28da46f394d37d4d51cc420e1ff9414a (diff) | |
io_uring: don't touch ctx in setup after ring fd install
syzkaller reported an issue where it looks like a malicious app can
trigger a use-after-free of reading the ctx ->sq_array and ->rings
value right after having installed the ring fd in the process file
table.
Defer ring fd installation until after we're done reading those
values.
Fixes: 75b28affdd6a ("io_uring: allocate the two rings together")
Reported-by: syzbot+6f03d895a6cd0d06187f@syzkaller.appspotmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/io_uring.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index ba1431046c98..c11c4157a4c2 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -3829,10 +3829,6 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) if (ret) goto err; - ret = io_uring_get_fd(ctx); - if (ret < 0) - goto err; - memset(&p->sq_off, 0, sizeof(p->sq_off)); p->sq_off.head = offsetof(struct io_rings, sq.head); p->sq_off.tail = offsetof(struct io_rings, sq.tail); @@ -3850,6 +3846,14 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) p->cq_off.overflow = offsetof(struct io_rings, cq_overflow); p->cq_off.cqes = offsetof(struct io_rings, cqes); + /* + * Install ring fd as the very last thing, so we don't risk someone + * having closed it before we finish setup + */ + ret = io_uring_get_fd(ctx); + if (ret < 0) + goto err; + p->features = IORING_FEAT_SINGLE_MMAP; return ret; err: |