| Message ID | 1493980011-24395-1-git-send-email-jiyin@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
----- 原始邮件 ----- > 发件人: "Anna Schumaker" <Anna.Schumaker@Netapp.com> > 收件人: "Jianhong.Yin" <jiyin@redhat.com>, linux-nfs@vger.kernel.org > 抄送: "trond myklebust" <trond.myklebust@primarydata.com>, bfields@redhat.com, steved@redhat.com, "Jianhong.Yin" > <yin-jianhong@163.com> > 发送时间: 星期六, 2017年 5 月 06日 上午 1:52:35 > 主题: Re: [PATCH] fs/nfs: fix covscan error: FORWARD_NULL > > Hi Jianhong, > > On 05/05/2017 06:26 AM, Jianhong.Yin wrote: > > From: "Jianhong.Yin" <yin-jianhong@163.com> > > > > fs/nfs/nfs4xdr.c: encode_attrs() > > ''' > > Error: FORWARD_NULL (CWE-476): [#def3702] > > .../fs/nfs/nfs4xdr.c:1085: var_compare_op: Comparing "label" to null > > implies that "label" might be null. > > .../fs/nfs/nfs4xdr.c:1129: var_deref_op: Dereferencing null pointer > > "label". > > 1127| } > > 1128| if (bmval[2] & FATTR4_WORD2_SECURITY_LABEL) { > > 1129|-> *p++ = cpu_to_be32(label->lfs); > > 1130| *p++ = cpu_to_be32(label->pi); > > 1131| *p++ = cpu_to_be32(label->len); > > > > Error: FORWARD_NULL (CWE-476): [#def3703] > > .../fs/nfs/nfs4xdr.c:1027: var_compare_op: Comparing "umask" to null > > implies that "umask" might be null. > > .../fs/nfs/nfs4xdr.c:1136: var_deref_op: Dereferencing null pointer > > "umask". > > 1134| if (bmval[2] & FATTR4_WORD2_MODE_UMASK) { > > 1135| *p++ = cpu_to_be32(iap->ia_mode & S_IALLUGO); > > 1136|-> *p++ = cpu_to_be32(*umask); > > 1137| } > > ''' > > > > Signed-off-by: Jianhong Yin <yin-jianhong@163.com> > > --- > > fs/nfs/nfs4xdr.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c > > index 80ce289..a86ed66 100644 > > --- a/fs/nfs/nfs4xdr.c > > +++ b/fs/nfs/nfs4xdr.c > > @@ -1124,7 +1124,7 @@ static void encode_attrs(struct xdr_stream *xdr, > > const struct iattr *iap, > > } else > > *p++ = cpu_to_be32(NFS4_SET_TO_SERVER_TIME); > > } > > - if (bmval[2] & FATTR4_WORD2_SECURITY_LABEL) { > > + if (label && bmval[2] & FATTR4_WORD2_SECURITY_LABEL) { > > As far as I can tell, the FATTR4_WORD2_SECURITY_LABEL flag is only set if > label exists, and the same goes for the FATTR4_WORD2_MODE_UMASK flag below. > This means that it's not possible to have a null pointer dereference in > these sections of code. Is there a way to mark this as a false positive in > your covscan tool? Hi Anna Yes, you are right. this patch is unnecessary. just let code *looks* more safe. "covscan" means the coverity scan(a "Static Analysis" tool). lots of it's warning/error need to be marked as false positive. thank you for correcting me Jianhong > > Thanks, > Anna > > > *p++ = cpu_to_be32(label->lfs); > > *p++ = cpu_to_be32(label->pi); > > *p++ = cpu_to_be32(label->len); > > @@ -1132,7 +1132,8 @@ static void encode_attrs(struct xdr_stream *xdr, > > const struct iattr *iap, > > } > > if (bmval[2] & FATTR4_WORD2_MODE_UMASK) { > > *p++ = cpu_to_be32(iap->ia_mode & S_IALLUGO); > > - *p++ = cpu_to_be32(*umask); > > + if (umask != NULL) > > + *p++ = cpu_to_be32(*umask); > > } > > > > /* out: */ > > > -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c index 80ce289..a86ed66 100644 --- a/fs/nfs/nfs4xdr.c +++ b/fs/nfs/nfs4xdr.c @@ -1124,7 +1124,7 @@ static void encode_attrs(struct xdr_stream *xdr, const struct iattr *iap, } else *p++ = cpu_to_be32(NFS4_SET_TO_SERVER_TIME); } - if (bmval[2] & FATTR4_WORD2_SECURITY_LABEL) { + if (label && bmval[2] & FATTR4_WORD2_SECURITY_LABEL) { *p++ = cpu_to_be32(label->lfs); *p++ = cpu_to_be32(label->pi); *p++ = cpu_to_be32(label->len); @@ -1132,7 +1132,8 @@ static void encode_attrs(struct xdr_stream *xdr, const struct iattr *iap, } if (bmval[2] & FATTR4_WORD2_MODE_UMASK) { *p++ = cpu_to_be32(iap->ia_mode & S_IALLUGO); - *p++ = cpu_to_be32(*umask); + if (umask != NULL) + *p++ = cpu_to_be32(*umask); } /* out: */