Commit bf3858da authored by Josef Bacik's avatar Josef Bacik Committed by Long Li
Browse files

nfs: fix UAF in direct writes 

stable inclusion
from stable-v5.10.215
commit 4595d90b5d2ea5fa4d318d13f59055aa4bf3e7f5
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I9L5GC
CVE: CVE-2024-26958

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-5.10.y&id=4595d90b5d2ea5fa4d318d13f59055aa4bf3e7f5



--------------------------------

[ Upstream commit 17f46b803d4f23c66cacce81db35fef3adb8f2af ]

In production we have been hitting the following warning consistently

------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 17 PID: 1800359 at lib/refcount.c:28 refcount_warn_saturate+0x9c/0xe0
Workqueue: nfsiod nfs_direct_write_schedule_work [nfs]
RIP: 0010:refcount_warn_saturate+0x9c/0xe0
PKRU: 55555554
Call Trace:
 <TASK>
 ? __warn+0x9f/0x130
 ? refcount_warn_saturate+0x9c/0xe0
 ? report_bug+0xcc/0x150
 ? handle_bug+0x3d/0x70
 ? exc_invalid_op+0x16/0x40
 ? asm_exc_invalid_op+0x16/0x20
 ? refcount_warn_saturate+0x9c/0xe0
 nfs_direct_write_schedule_work+0x237/0x250 [nfs]
 process_one_work+0x12f/0x4a0
 worker_thread+0x14e/0x3b0
 ? ZSTD_getCParams_internal+0x220/0x220
 kthread+0xdc/0x120
 ? __btf_name_valid+0xa0/0xa0
 ret_from_fork+0x1f/0x30

This is because we're completing the nfs_direct_request twice in a row.

The source of this is when we have our commit requests to submit, we
process them and send them off, and then in the completion path for the
commit requests we have

if (nfs_commit_end(cinfo.mds))
	nfs_direct_write_complete(dreq);

However since we're submitting asynchronous requests we sometimes have
one that completes before we submit the next one, so we end up calling
complete on the nfs_direct_request twice.

The only other place we use nfs_generic_commit_list() is in
__nfs_commit_inode, which wraps this call in a

nfs_commit_begin();
nfs_commit_end();

Which is a common pattern for this style of completion handling, one
that is also repeated in the direct code with get_dreq()/put_dreq()
calls around where we process events as well as in the completion paths.

Fix this by using the same pattern for the commit requests.

Before with my 200 node rocksdb stress running this warning would pop
every 10ish minutes.  With my patch the stress test has been running for
several hours without popping.

Signed-off-by: default avatarJosef Bacik <josef@toxicpanda.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarLong Li <leo.lilong@huawei.com>
parent e706c6b6

fs/nfs/direct.c

+9 −2
Original line number Diff line number Diff line
@@ -678,10 +678,17 @@ static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq) 
	LIST_HEAD(mds_list);



	nfs_init_cinfo_from_dreq(&cinfo, dreq);

	nfs_commit_begin(cinfo.mds);

	nfs_scan_commit(dreq->inode, &mds_list, &cinfo);

	res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo);

	if (res < 0) /* res == -ENOMEM */

		nfs_direct_write_reschedule(dreq);

	if (res < 0) { /* res == -ENOMEM */

		spin_lock(&dreq->lock);

		if (dreq->flags == 0)

			dreq->flags = NFS_ODIRECT_RESCHED_WRITES;

		spin_unlock(&dreq->lock);

	}

	if (nfs_commit_end(cinfo.mds))

		nfs_direct_write_complete(dreq);

}



static void nfs_direct_write_clear_reqs(struct nfs_direct_req *dreq)

fs/nfs/write.c

+1 −1
Original line number Diff line number Diff line
@@ -1634,7 +1634,7 @@ static int wait_on_commit(struct nfs_mds_commit_info *cinfo) 
				       !atomic_read(&cinfo->rpcs_out));

}



static void nfs_commit_begin(struct nfs_mds_commit_info *cinfo)

void nfs_commit_begin(struct nfs_mds_commit_info *cinfo)

{

	atomic_inc(&cinfo->rpcs_out);

}

include/linux/nfs_fs.h

+1 −0
Original line number Diff line number Diff line
@@ -553,6 +553,7 @@ extern int nfs_wb_page_cancel(struct inode *inode, struct page* page); 
extern int  nfs_commit_inode(struct inode *, int);

extern struct nfs_commit_data *nfs_commitdata_alloc(void);

extern void nfs_commit_free(struct nfs_commit_data *data);

void nfs_commit_begin(struct nfs_mds_commit_info *cinfo);

bool nfs_commit_end(struct nfs_mds_commit_info *cinfo);



static inline int