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nfsd: fix stale s2s_cp_stateids IDR entry for async COPY

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For an async COPY, nfsd4_copy() called nfs4_init_copy_state() before
dup_copy_fields(), so the s2s_cp_stateids IDR was pointed at
&u->copy->cp_stateid -- memory in the per-rqstp COMPOUND buffer that is
reused by the next request. dup_copy_fields() copies only the value into
async_copy, so the IDR slot dangled at the transient buffer for the whole
background copy. Any IDR walker then dereferences reused request memory:
the laundromat reads cs_type from it and, if the bytes look like an
expired NFS4_COPYNOTIFY_STID, follows into
refcount_dec()/idr_remove()/kfree() on garbage; manage_cpntf_state() has
the same exposure via idr_find().

Duplicate the fields first, then register the stateid on the stable
async_copy. result->cb_stateid is unchanged.

Fixes: e0639dc580 ("NFSD introduce async copy feature")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260710-nfsd-testing-v3-3-a0ff7db6aa3e@kernel.org
Signed-off-by: Chuck Lever <cel@kernel.org>
This commit is contained in:
Jeff Layton 2026-07-10 10:00:07 -04:00 committed by Chuck Lever
parent 62c0f6eaf0
commit d0beaee498
1 changed files with 5 additions and 4 deletions
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9
fs/nfsd/nfs4proc.c
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@ -2237,11 +2237,12 @@ nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
async_copy->cp_src = kmalloc_obj(*async_copy->cp_src);
if (!async_copy->cp_src)
goto out_dec_async_copy_err;
if (!nfs4_init_copy_state(nn, copy))
goto out_dec_async_copy_err;
memcpy(&result->cb_stateid, &copy->cp_stateid.cs_stid,
sizeof(result->cb_stateid));
dup_copy_fields(copy, async_copy);
if (!nfs4_init_copy_state(nn, async_copy))
goto out_dec_async_copy_err;
memcpy(&result->cb_stateid, &async_copy->cp_stateid.cs_stid,
sizeof(result->cb_stateid));
if ((READ_ONCE(copy->nf_dst->nf_file->f_mode) &
FMODE_NOCMTIME) != 0)
async_copy->attr_update = true;