NFSD: Prevent a potential integer overflow
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.
BUG=b/388469395
TEST=presubmit
RELEASE_NOTE=Fixed CVE-2024-53146 in the Linux kernel.
cos-patch: security-moderate
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Cc: stable@vger.kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Change-Id: I5ea1d505146d06a60c9dfa2c0e3b080f554a156e
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kernel CVE Triage Automation <cloud-image-kernel-cve-triage-automation@prod.google.com>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/89879
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Anil Altinay <aaltinay@google.com>
Reviewed-by: Kevin Berry <kpberry@google.com>
diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 4eae2c5..ed3210a 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -297,17 +297,17 @@ static int decode_cb_compound4res(struct xdr_stream *xdr,
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;
- p += XDR_QUADLEN(length);
- hdr->nops = be32_to_cpup(p);
+ if (xdr_inline_decode(xdr, length) == NULL)
+ goto out_overflow;
+ if (xdr_stream_decode_u32(xdr, &hdr->nops) < 0)
+ goto out_overflow;
return 0;
out_overflow:
return -EIO;
