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Message-ID: <c3180839-a103-4f15-8a8d-ad8b654c4294@huawei.com>
Date: Sun, 26 Jan 2025 11:45:03 +0800
From: Li Lingfeng <lilingfeng3@...wei.com>
To: "zhangjian (CG)" <zhangjian496@...wei.com>, Li Lingfeng
<lilingfeng@...weicloud.com>, <chuck.lever@...cle.com>, <jlayton@...nel.org>,
<neilb@...e.de>, <okorniev@...hat.com>, <kolga@...app.com>,
<Dai.Ngo@...cle.com>, <tom@...pey.com>, <Trond.Myklebust@...app.com>,
<linux-nfs@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC: <yukuai1@...weicloud.com>, <houtao1@...wei.com>, <yi.zhang@...wei.com>,
<yangerkun@...wei.com>
Subject: Re: [PATCH] nfsd: set acl_access/acl_default after getting successful
在 2024/11/28 9:17, zhangjian (CG) 写道:
> there is one case when disk error cause get_inode_acl(inode,
> ACL_TYPE_DEFAULT) return EIO,
> resp->acl_access will not be null.
> posix_acl_release(resp->acl_default) will trigger this warning.
>
Yes, in the problematic scenario, resp->acl_access would not be NULL.
The memory pointed to by resp->acl_access would be freed and then accessed
again, thereby triggering the issue.
>
>> If getting acl_default fails, acl_access and acl_default will be
>> released
>> simultaneously. However, acl_access will still retain a pointer pointing
>> to the released posix_acl, which will trigger a WARNING in
>> nfs3svc_release_getacl like this:
>>
>> ------------[ cut here ]------------
>> refcount_t: underflow; use-after-free.
>> WARNING: CPU: 26 PID: 3199 at lib/refcount.c:28
>> refcount_warn_saturate+0xb5/0x170
>> Modules linked in:
>> CPU: 26 UID: 0 PID: 3199 Comm: nfsd Not tainted
>> 6.12.0-rc6-00079-g04ae226af01f-dirty #8
>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
>> 1.16.1-2.fc37 04/01/2014
>> RIP: 0010:refcount_warn_saturate+0xb5/0x170
>> Code: cc cc 0f b6 1d b3 20 a5 03 80 fb 01 0f 87 65 48 d8 00 83 e3 01 75
>> e4 48 c7 c7 c0 3b 9b 85 c6 05 97 20 a5 03 01 e8 fb 3e 30 ff <0f> 0b eb
>> cd 0f b6 1d 8a3
>> RSP: 0018:ffffc90008637cd8 EFLAGS: 00010282
>> RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff83904fde
>> RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffff88871ed36380
>> RBP: ffff888158beeb40 R08: 0000000000000001 R09: fffff520010c6f56
>> R10: ffffc90008637ab7 R11: 0000000000000001 R12: 0000000000000001
>> R13: ffff888140e77400 R14: ffff888140e77408 R15: ffffffff858b42c0
>> FS: 0000000000000000(0000) GS:ffff88871ed00000(0000)
>> knlGS:0000000000000000
>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 0000562384d32158 CR3: 000000055cc6a000 CR4: 00000000000006f0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> Call Trace:
>> <TASK>
>> ? refcount_warn_saturate+0xb5/0x170
>> ? __warn+0xa5/0x140
>> ? refcount_warn_saturate+0xb5/0x170
>> ? report_bug+0x1b1/0x1e0
>> ? handle_bug+0x53/0xa0
>> ? exc_invalid_op+0x17/0x40
>> ? asm_exc_invalid_op+0x1a/0x20
>> ? tick_nohz_tick_stopped+0x1e/0x40
>> ? refcount_warn_saturate+0xb5/0x170
>> ? refcount_warn_saturate+0xb5/0x170
>> nfs3svc_release_getacl+0xc9/0xe0
>> svc_process_common+0x5db/0xb60
>> ? __pfx_svc_process_common+0x10/0x10
>> ? __rcu_read_unlock+0x69/0xa0
>> ? __pfx_nfsd_dispatch+0x10/0x10
>> ? svc_xprt_received+0xa1/0x120
>> ? xdr_init_decode+0x11d/0x190
>> svc_process+0x2a7/0x330
>> svc_handle_xprt+0x69d/0x940
>> svc_recv+0x180/0x2d0
>> nfsd+0x168/0x200
>> ? __pfx_nfsd+0x10/0x10
>> kthread+0x1a2/0x1e0
>> ? kthread+0xf4/0x1e0
>> ? __pfx_kthread+0x10/0x10
>> ret_from_fork+0x34/0x60
>> ? __pfx_kthread+0x10/0x10
>> ret_from_fork_asm+0x1a/0x30
>> </TASK>
>> Kernel panic - not syncing: kernel: panic_on_warn set ...
>>
>> Clear acl_access/acl_default first and set both of them only when both
>> ACLs are successfully obtained.
>>
>> Fixes: a257cdd0e217 ("[PATCH] NFSD: Add server support for NFSv3 ACLs.")
>> Signed-off-by: Li Lingfeng <lilingfeng@...weicloud.com>
>> ---
>> fs/nfsd/nfs3acl.c | 14 ++++++++------
>> 1 file changed, 8 insertions(+), 6 deletions(-)
>>
>> diff --git a/fs/nfsd/nfs3acl.c b/fs/nfsd/nfs3acl.c
>> index 5e34e98db969..17579a032a5b 100644
>> --- a/fs/nfsd/nfs3acl.c
>> +++ b/fs/nfsd/nfs3acl.c
>> @@ -29,10 +29,12 @@ static __be32 nfsd3_proc_getacl(struct svc_rqst
>> *rqstp)
>> {
>> struct nfsd3_getaclargs *argp = rqstp->rq_argp;
>> struct nfsd3_getaclres *resp = rqstp->rq_resp;
>> - struct posix_acl *acl;
>> + struct posix_acl *acl = NULL, *dacl = NULL;
>> struct inode *inode;
>> svc_fh *fh;
>> + resp->acl_access = NULL;
>> + resp->acl_default = NULL;
>> fh = fh_copy(&resp->fh, &argp->fh);
>> resp->status = fh_verify(rqstp, &resp->fh, 0, NFSD_MAY_NOP);
>> if (resp->status != nfs_ok)
>> @@ -56,19 +58,19 @@ static __be32 nfsd3_proc_getacl(struct svc_rqst
>> *rqstp)
>> resp->status = nfserrno(PTR_ERR(acl));
>> goto fail;
>> }
>> - resp->acl_access = acl;
>> }
>> if (resp->mask & (NFS_DFACL|NFS_DFACLCNT)) {
>> /* Check how Solaris handles requests for the Default ACL
>> of a non-directory! */
>> - acl = get_inode_acl(inode, ACL_TYPE_DEFAULT);
>> - if (IS_ERR(acl)) {
>> - resp->status = nfserrno(PTR_ERR(acl));
>> + dacl = get_inode_acl(inode, ACL_TYPE_DEFAULT);
>> + if (IS_ERR(dacl)) {
>> + resp->status = nfserrno(PTR_ERR(dacl));
>> goto fail;
>> }
>> - resp->acl_default = acl;
>> }
>> + resp->acl_access = acl;
>> + resp->acl_default = dacl;
>> /* resp->acl_{access,default} are released in
>> nfs3svc_release_getacl. */
>> out:
>> return rpc_success;
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