[PATCH 4.9 15/26] ceph: fix buffer free while holding i_ceph_lock in fill_inode()

Greg Kroah-Hartman
2019-09-08T12:44:15Z

[ Upstream commit af8a85a41734f37b67ba8ce69d56b685bee4ac48 ]

Calling ceph_buffer_put() in fill_inode() may result in freeing the
i_xattrs.blob buffer while holding the i_ceph_lock. This can be fixed by
postponing the call until later, when the lock is released.

The following backtrace was triggered by fstests generic/070.

BUG: sleeping function called from invalid context at mm/vmalloc.c:2283
in_atomic(): 1, irqs_disabled(): 0, pid: 3852, name: kworker/0:4
6 locks held by kworker/0:4/3852:
#0: 000000004270f6bb ((wq_completion)ceph-msgr){+.+.}, at: process_one_work+0x1b8/0x5f0
#1: 00000000eb420803 ((work_completion)(&(&con->work)->work)){+.+.}, at: process_one_work+0x1b8/0x5f0
#2: 00000000be1c53a4 (&s->s_mutex){+.+.}, at: dispatch+0x288/0x1476
#3: 00000000559cb958 (&mdsc->snap_rwsem){++++}, at: dispatch+0x2eb/0x1476
#4: 000000000d5ebbae (&req->r_fill_mutex){+.+.}, at: dispatch+0x2fc/0x1476
#5: 00000000a83d0514 (&(&ci->i_ceph_lock)->rlock){+.+.}, at: fill_inode.isra.0+0xf8/0xf70
CPU: 0 PID: 3852 Comm: kworker/0:4 Not tainted 5.2.0+ #441
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58-prebuilt.qemu.org 04/01/2014
Workqueue: ceph-msgr ceph_con_workfn
Call Trace:
dump_stack+0x67/0x90
___might_sleep.cold+0x9f/0xb1
vfree+0x4b/0x60
ceph_buffer_release+0x1b/0x60
fill_inode.isra.0+0xa9b/0xf70
ceph_fill_trace+0x13b/0xc70
? dispatch+0x2eb/0x1476
dispatch+0x320/0x1476
? __mutex_unlock_slowpath+0x4d/0x2a0
ceph_con_workfn+0xc97/0x2ec0
? process_one_work+0x1b8/0x5f0
process_one_work+0x244/0x5f0
worker_thread+0x4d/0x3e0
kthread+0x105/0x140
? process_one_work+0x5f0/0x5f0
? kthread_park+0x90/0x90
ret_from_fork+0x3a/0x50

Signed-off-by: Luis Henriques <lhenriques@suse.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/ceph/inode.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 7a4052501866d..339fdf6355df7 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -741,6 +741,7 @@ static int fill_inode(struct inode *inode, struct page *locked_page,
int issued = 0, implemented, new_issued;
struct timespec mtime, atime, ctime;
struct ceph_buffer *xattr_blob = NULL;
+ struct ceph_buffer *old_blob = NULL;
struct ceph_string *pool_ns = NULL;
struct ceph_cap *new_cap = NULL;
int err = 0;
@@ -858,7 +859,7 @@ static int fill_inode(struct inode *inode, struct page *locked_page,
if ((ci->i_xattrs.version == 0 || !(issued & CEPH_CAP_XATTR_EXCL)) &&
le64_to_cpu(info->xattr_version) > ci->i_xattrs.version) {
if (ci->i_xattrs.blob)
- ceph_buffer_put(ci->i_xattrs.blob);
+ old_blob = ci->i_xattrs.blob;
ci->i_xattrs.blob = xattr_blob;
if (xattr_blob)
memcpy(ci->i_xattrs.blob->vec.iov_base,
@@ -1004,8 +1005,8 @@ static int fill_inode(struct inode *inode, struct page *locked_page,
out:
if (new_cap)
ceph_put_cap(mdsc, new_cap);
- if (xattr_blob)
- ceph_buffer_put(xattr_blob);
+ ceph_buffer_put(old_blob);
+ ceph_buffer_put(xattr_blob);
ceph_put_string(pool_ns);
return err;
}
--
2.20.1