On 3/5/22 2:20 AM, Jeff Layton wrote:
On Fri, 2022-03-04 at 16:14 +0000, Luís Henriques wrote:After calling ceph_mdsc_put_request() on dfi->last_readdir, this field should be set to NULL, otherwise we may end-up freeing it twince and get the following splat: refcount_t: underflow; use-after-free. WARNING: CPU: 0 PID: 229 at lib/refcount.c:28 refcount_warn_saturate+0xa6/0xf0 ... Call Trace: <TASK> ceph_readdir+0xd35/0x1460 [ceph] ? _raw_spin_unlock+0x12/0x30 ? preempt_count_add+0x73/0xa0 ? _raw_spin_unlock+0x12/0x30 ? __mark_inode_dirty+0x27c/0x3a0 iterate_dir+0x7d/0x190 __x64_sys_getdents64+0x80/0x120 ? compat_fillonedir+0x160/0x160 do_syscall_64+0x43/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae Signed-off-by: Luís Henriques <lhenriques@xxxxxxx> --- fs/ceph/dir.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c index 0bcb677d2199..934402f5e9e6 100644 --- a/fs/ceph/dir.c +++ b/fs/ceph/dir.c @@ -555,6 +555,7 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx) le32_to_cpu(rde->inode.in->mode) >> 12)) { dout("filldir stopping us...\n"); ceph_mdsc_put_request(dfi->last_readdir); + dfi->last_readdir = NULL; err = 0; goto out; }I think Xiubo fixed this in the testing branch late yesterday. It should no longer be needed.
Right and I have sent a new version of my previous patch to remove the buggy code.
- Xiubo
Thanks,
