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| author | Michael Bommarito <michael.bommarito@gmail.com> | 2026-05-27 12:30:35 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-07-04 13:39:40 +0200 |
| commit | 76b94cbd32aacf36a641956385a852635c6802b9 (patch) | |
| tree | c6d02847d1a740388fbbe8b5ebe90ae3374f4895 | |
| parent | db1c612eb5115432f30888c301c45c7ea60a4a13 (diff) | |
| download | linux-76b94cbd32aacf36a641956385a852635c6802b9.tar.gz linux-76b94cbd32aacf36a641956385a852635c6802b9.zip | |
NFSv4/pNFS: reject zero-length r_addr in nfs4_decode_mp_ds_addr
commit 41fe0f7b84f0cb822ae10ab08592996a592b2a25 upstream.
nfs4_decode_mp_ds_addr() decodes the r_netid and r_addr opaques of a
netaddr4 from a GETDEVICEINFO multipath-DS body, then immediately
calls strrchr(buf, '.') to locate the port separator. Both decodes
use xdr_stream_decode_string_dup(), and the current code checks only
"nlen < 0" / "rlen < 0" before dereferencing the returned string.
When the on-wire opaque has length zero, xdr_stream_decode_opaque_inline()
returns 0 and xdr_stream_decode_string_dup() falls through to its
"*str = NULL; return ret" tail, leaving buf NULL with a return value
of 0. The "< 0" check does not catch this, and the next line is
strrchr(NULL, '.'), a kernel NULL pointer dereference reachable from
any pNFS-flexfile client mounted against a malicious or compromised
metadata server.
Reject the zero-length cases explicitly so the decoder fails with
-EBADMSG (treated as a malformed GETDEVICEINFO body) instead of
panicking the client.
Cc: stable@vger.kernel.org
Fixes: 6b7f3cf96364 ("nfs41: pull decode_ds_addr from file layout to generic pnfs")
Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
Signed-off-by: Anna Schumaker <anna.schumaker@hammerspace.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | fs/nfs/pnfs_nfs.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/nfs/pnfs_nfs.c b/fs/nfs/pnfs_nfs.c index 29c1c7f80b1d..955e95685d16 100644 --- a/fs/nfs/pnfs_nfs.c +++ b/fs/nfs/pnfs_nfs.c @@ -1057,14 +1057,14 @@ nfs4_decode_mp_ds_addr(struct net *net, struct xdr_stream *xdr, gfp_t gfp_flags) /* r_netid */ nlen = xdr_stream_decode_string_dup(xdr, &netid, XDR_MAX_NETOBJ, gfp_flags); - if (unlikely(nlen < 0)) + if (unlikely(nlen <= 0)) goto out_err; /* r_addr: ip/ip6addr with port in dec octets - see RFC 5665 */ /* port is ".ABC.DEF", 8 chars max */ rlen = xdr_stream_decode_string_dup(xdr, &buf, INET6_ADDRSTRLEN + IPV6_SCOPE_ID_LEN + 8, gfp_flags); - if (unlikely(rlen < 0)) + if (unlikely(rlen <= 0)) goto out_free_netid; /* replace port '.' with '-' */ |