From: Chuck Lever chuck.lever@oracle.com

stable inclusion from stable-v5.10.221 commit 38d02ba22e43b6fc7d291cf724bc6e3b7be6626b category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IADGCI CVE: CVE-2022-48828

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=l...

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[ Upstream commit e6faac3f58c7c4176b66f63def17a34232a17b0e ]

iattr::ia_size is a loff_t, which is a signed 64-bit type. NFSv3 and NFSv4 both define file size as an unsigned 64-bit type. Thus there is a range of valid file size values an NFS client can send that is already larger than Linux can handle.

Currently decode_fattr4() dumps a full u64 value into ia_size. If that value happens to be larger than S64_MAX, then ia_size underflows. I'm about to fix up the NFSv3 behavior as well, so let's catch the underflow in the common code path: nfsd_setattr().

Cc: stable@vger.kernel.org [ cel: context adjusted, 2f221d6f7b88 has not been applied ] Signed-off-by: Chuck Lever chuck.lever@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Xia Fukun xiafukun@huawei.com --- fs/nfsd/vfs.c | 4 ++++ 1 file changed, 4 insertions(+)

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 31edb883afd0d..7820945e2d075 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -448,6 +448,10 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap, .ia_size = iap->ia_size, };

+ host_err = -EFBIG; + if (iap->ia_size < 0) + goto out_unlock; + host_err = notify_change(dentry, &size_attr, NULL); if (host_err) goto out_unlock;