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ceph: do not access the kiocb after aio requests 

In aio case, if the completion comes very fast just before the
ceph_read_iter() returns to fs/aio.c, the kiocb will be freed in
the completion callback, then if ceph_read_iter() access again
we will potentially hit the use-after-free bug.

[ jlayton: initialize direct_lock early, and use it everywhere ]

URL: https://tracker.ceph.com/issues/45649
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
This commit is contained in:
Xiubo Li 2020-07-06 08:51:35 -04:00 committed by Ilya Dryomov
parent 585d72f33e
commit d1d9655052
1 changed files with 3 additions and 2 deletions
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5
fs/ceph/file.c
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@ -1538,6 +1538,7 @@ static ssize_t ceph_read_iter(struct kiocb *iocb, struct iov_iter *to)
struct inode *inode = file_inode(filp);
struct ceph_inode_info *ci = ceph_inode(inode);
struct page *pinned_page = NULL;
bool direct_lock = iocb->ki_flags & IOCB_DIRECT;
ssize_t ret;
int want, got = 0;
int retry_op = 0, read = 0;
@ -1546,7 +1547,7 @@ again:
dout("aio_read %p %llx.%llx %llu~%u trying to get caps on %p\n",
inode, ceph_vinop(inode), iocb->ki_pos, (unsigned)len, inode);
if (iocb->ki_flags & IOCB_DIRECT)
if (direct_lock)
ceph_start_io_direct(inode);
else
ceph_start_io_read(inode);
@ -1603,7 +1604,7 @@ again:
}
ceph_put_cap_refs(ci, got);
if (iocb->ki_flags & IOCB_DIRECT)
if (direct_lock)
ceph_end_io_direct(inode);
else
ceph_end_io_read(inode);