5.4-stable review patch. If anyone has any objections, please let me know.
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From: Chuck Lever chuck.lever@oracle.com
commit 7f33b92e5b18e904a481e6e208486da43e4dc841 upstream.
If the tag length is >= U32_MAX - 3 then the "length + 4" addition can result in an integer overflow. Address this by splitting the decoding into several steps so that decode_cb_compound4res() does not have to perform arithmetic on the unsafe length value.
Reported-by: Dan Carpenter dan.carpenter@linaro.org Cc: stable@vger.kernel.org Reviewed-by: Jeff Layton jlayton@kernel.org Signed-off-by: Chuck Lever chuck.lever@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/nfsd/nfs4callback.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)
--- a/fs/nfsd/nfs4callback.c +++ b/fs/nfsd/nfs4callback.c @@ -285,17 +285,17 @@ static int decode_cb_compound4res(struct u32 length; __be32 *p;
- p = xdr_inline_decode(xdr, 4 + 4); + p = xdr_inline_decode(xdr, XDR_UNIT); if (unlikely(p == NULL)) goto out_overflow; - hdr->status = be32_to_cpup(p++); + hdr->status = be32_to_cpup(p); /* Ignore the tag */ - length = be32_to_cpup(p++); - p = xdr_inline_decode(xdr, length + 4); - if (unlikely(p == NULL)) + if (xdr_stream_decode_u32(xdr, &length) < 0) + goto out_overflow; + if (xdr_inline_decode(xdr, length) == NULL) + goto out_overflow; + if (xdr_stream_decode_u32(xdr, &hdr->nops) < 0) goto out_overflow; - p += XDR_QUADLEN(length); - hdr->nops = be32_to_cpup(p); return 0; out_overflow: return -EIO;