Re: [edk2-devel] [PATCH v2] NetworkPkg/IScsiDxe: Fix the index of array TargetUrlp[]

["Zhang, Shenglei" <shenglei.zhang@intel.com>]

Hi Philippe,

> -----Original Message-----
> From: Philippe Mathieu-Daudé [mailto:philmd@redhat.com]
> Sent: Monday, October 14, 2019 5:35 PM
> To: devel@edk2.groups.io; Zhang, Shenglei <shenglei.zhang@intel.com>
> Cc: Fu, Siyuan <siyuan.fu@intel.com>; Wu, Jiaxin <jiaxin.wu@intel.com>;
> Laszlo Ersek <lersek@redhat.com>
> Subject: Re: [edk2-devel] [PATCH v2] NetworkPkg/IScsiDxe: Fix the index of
> array TargetUrlp[]
> 
> Hi Zhang,
> 
> On 10/14/19 5:14 AM, Zhang, Shenglei wrote:
> > After the expression,
> > 'CopyMem (&ConfigNvData->TargetUrl, Field->Str, Field->Len);',
> > the '\0' should be set to TargetUrl[Field->Len] rather than
> > TargetUrl[Field->Len + 1].
> 
> ^ This is one change, ...
> 
> > Besides the boundary check should be more strict.
> > Field->Len should range from 0-254 rather than 0-255.
> 
> ^ ... and here we have another change.
> 
> Can you split this in 2 patches?

I think these two changes should be included in one patch.
They are both about the variable ' Field->Len '. If one change pushed and the other one unchanged,
The logic is then wrong.

> 
> > Cc: Siyuan Fu <siyuan.fu@intel.com>
> > Cc: Jiaxin Wu <jiaxin.wu@intel.com>
> > Signed-off-by: Shenglei Zhang <shenglei.zhang@intel.com>
> > ---
> >
> > v2: Add missing ')' which causes build failure.
> >
> >   NetworkPkg/IScsiDxe/IScsiDhcp.c  | 7 ++++---
> >   NetworkPkg/IScsiDxe/IScsiDhcp6.c | 7 ++++---
> >   2 files changed, 8 insertions(+), 6 deletions(-)
> >
> > diff --git a/NetworkPkg/IScsiDxe/IScsiDhcp.c
> b/NetworkPkg/IScsiDxe/IScsiDhcp.c
> > index d8c9fff6c65d..eac5b39991b7 100644
> > --- a/NetworkPkg/IScsiDxe/IScsiDhcp.c
> > +++ b/NetworkPkg/IScsiDxe/IScsiDhcp.c
> > @@ -122,11 +122,12 @@ IScsiDhcpExtractRootPath (
> >     //
> >     if ((!NET_IS_DIGIT (*(Field->Str))) && (*(Field->Str) != '[')) {
> >       ConfigNvData->DnsMode = TRUE;
> > -    if (Field->Len > sizeof (ConfigNvData->TargetUrl)) {
> > -      return EFI_INVALID_PARAMETER;
> > +    if (Field->Len >= sizeof (ConfigNvData->TargetUrl)) {
> > +      Status = EFI_INVALID_PARAMETER;
> > +      goto ON_EXIT;
> 
> This is a change in the code flow. So now we free he allocated TmpStr.
> This is correct, but you did not commented that change in the
> description. So we currently have a memory leak. Please do not hide that
> kind of information in patches.

Yes the commit message should contain this change.

> 
> >       }
> >       CopyMem (&ConfigNvData->TargetUrl, Field->Str, Field->Len);
> > -    ConfigNvData->TargetUrl[Field->Len + 1] = '\0';
> > +    ConfigNvData->TargetUrl[Field->Len] = '\0';
> 
> And here we have 1 byte of memory info leak.
> 
> Are you fixing a Security BZ?

No, I found this issue by my local tool. There is no BZ for this.

Thanks,
Shenglei

> 
> >     } else {
> >       ConfigNvData->DnsMode = FALSE;
> >       ZeroMem(ConfigNvData->TargetUrl, sizeof (ConfigNvData->TargetUrl));
> > diff --git a/NetworkPkg/IScsiDxe/IScsiDhcp6.c
> b/NetworkPkg/IScsiDxe/IScsiDhcp6.c
> > index 86a872adeccc..be66e6684a0e 100644
> > --- a/NetworkPkg/IScsiDxe/IScsiDhcp6.c
> > +++ b/NetworkPkg/IScsiDxe/IScsiDhcp6.c
> > @@ -161,11 +161,12 @@ IScsiDhcp6ExtractRootPath (
> >     // Server name is expressed as domain name, just save it.
> >     //
> >     if (ConfigNvData->DnsMode) {
> > -    if (Field->Len > sizeof (ConfigNvData->TargetUrl)) {
> > -      return EFI_INVALID_PARAMETER;
> > +    if (Field->Len >= sizeof (ConfigNvData->TargetUrl)) {
> > +      Status = EFI_INVALID_PARAMETER;
> > +      goto ON_EXIT;
> >       }
> >       CopyMem (&ConfigNvData->TargetUrl, Field->Str, Field->Len);
> > -    ConfigNvData->TargetUrl[Field->Len + 1] = '\0';
> > +    ConfigNvData->TargetUrl[Field->Len] = '\0';
> >     } else {
> >       ZeroMem(&ConfigNvData->TargetUrl, sizeof (ConfigNvData-
> >TargetUrl));
> >       Status = IScsiAsciiStrToIp (Field->Str, IpMode, &Ip);
> >