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| author | Jeff Layton <jlayton@kernel.org> | 2026-05-30 09:19:25 -0400 |
|---|---|---|
| committer | Chuck Lever <cel@kernel.org> | 2026-07-05 21:07:22 -0400 |
| commit | b49f27ac5996a8b25f864ab9742817614e97b9a9 (patch) | |
| tree | 0dc335c872d98a4ce8e1933111a23f83d5c80e37 | |
| parent | df742662ce7e21c4e8c32c0dcfee78c0234bef80 (diff) | |
| download | linux-next-b49f27ac5996a8b25f864ab9742817614e97b9a9.tar.gz linux-next-b49f27ac5996a8b25f864ab9742817614e97b9a9.zip | |
nfsd: validate symlink target length in NFSv4 CREATE
nfsd4_decode_create() accepts an unbounded cr_datalen from the wire for
NF4LNK symlink targets, allowing a client to force a kmalloc of up to
the maximum RPC payload size (several MiB) per COMPOUND op that persists
until compound teardown. The VFS rejects oversized targets with
ENAMETOOLONG, but the allocation has already occurred.
Reject cr_datalen == 0 early with nfserr_inval and cr_datalen greater
than NFS4_MAXPATHLEN (PATH_MAX) with nfserr_nametoolong to bound the
allocation.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Assisted-by: kres:claude-opus-4-7
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260530-nfsd-fixes-v2-9-f27e8eb4d974@kernel.org
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
| -rw-r--r-- | fs/nfsd/nfs4xdr.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c index 09068ca61b00..c37c9722b8c6 100644 --- a/fs/nfsd/nfs4xdr.c +++ b/fs/nfsd/nfs4xdr.c @@ -964,6 +964,10 @@ nfsd4_decode_create(struct nfsd4_compoundargs *argp, union nfsd4_op_u *u) case NF4LNK: if (xdr_stream_decode_u32(argp->xdr, &create->cr_datalen) < 0) return nfserr_bad_xdr; + if (create->cr_datalen == 0) + return nfserr_inval; + if (create->cr_datalen > NFS4_MAXPATHLEN) + return nfserr_nametoolong; p = xdr_inline_decode(argp->xdr, create->cr_datalen); if (!p) return nfserr_bad_xdr; |