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nfsd: fix XDR padding calculation in ff_encode_getdeviceinfo

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nfsd4_ff_encode_getdeviceinfo() computes the da_addr_body reservation
as 16 + netid_len + addr_len, but the subsequent xdr_encode_opaque()
calls emit 8 + round_up(netid_len, 4) + round_up(addr_len, 4) bytes.
The mismatch means the declared da_addr_body length exceeds the actual
encoded data by 2-8 bytes on every flexfile GETDEVICEINFO reply,
leaking stale reply-page content to the client and mis-aligning the
subsequent version list decode.

Use xdr_align_size() for each string length to match what
xdr_encode_opaque() actually writes.

Fixes: efcae97fa425 ("NFSD: da_addr_body field missing in some GETDEVICEINFO replies")
Cc: stable@vger.kernel.org
Assisted-by: kres:claude-opus-4-6
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260527-pnfs-fixes-v1-1-784f39dc1eca@kernel.org
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Jeff Layton
2026-05-27 14:30:41 -04:00
committed by Chuck Lever
parent 01500306e1
commit 8b989aaec8
1 changed files with 2 additions and 1 deletions
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3
fs/nfsd/flexfilelayoutxdr.c
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@@ -94,7 +94,8 @@ nfsd4_ff_encode_getdeviceinfo(struct xdr_stream *xdr,
}
/* len + padding for two strings */
addr_len = 16 + da->netaddr.netid_len + da->netaddr.addr_len;
addr_len = 8 + xdr_align_size(da->netaddr.netid_len) +
xdr_align_size(da->netaddr.addr_len);
ver_len = 20;
len = 4 + ver_len + 4 + addr_len;