Re: [edk2-devel] [PATCH v2 1/1] MdePkg : UefiFileHandleLib: fix buffer overrun in FileHandleReadLine()

["Laszlo Ersek" <lersek@redhat.com>]

On 07/03/20 04:30, Zhiguang Liu wrote:
> Reviewed-by: Zhiguang Liu <zhiguang.liu@intel.com>

Merged as commit 4535fc312b76, via
<https://github.com/tianocore/edk2/pull/896>.

Thanks,
Laszlo

> 
>> -----Original Message-----
>> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Vladimir
>> Olovyannikov via groups.io
>> Sent: Thursday, July 2, 2020 10:31 AM
>> To: devel@edk2.groups.io
>> Cc: Vladimir Olovyannikov <vladimir.olovyannikov@broadcom.com>; Kinney,
>> Michael D <michael.d.kinney@intel.com>; Gao, Liming
>> <liming.gao@intel.com>; Liu, Zhiguang <zhiguang.liu@intel.com>
>> Subject: [edk2-devel] [PATCH v2 1/1] MdePkg : UefiFileHandleLib: fix buffer
>> overrun in FileHandleReadLine()
>>
>> If the size of the supplied buffer in FileHandleReadLine(), module
>> UefiFileHandleLib.c, was not 0, but was not enough to fit in
>> the line, the size is increased, and then the Buffer of the new
>> size is zeroed. This size is always larger than the supplied buffer size,
>> causing supplied buffer overrun. Fix the issue by using the
>> supplied buffer size in ZeroMem().
>>
>> Signed-off-by: Vladimir Olovyannikov
>> <vladimir.olovyannikov@broadcom.com>
>> Cc: Michael D Kinney <michael.d.kinney@intel.com>
>> Cc: Liming Gao <liming.gao@intel.com>
>> Cc: Zhiguang Liu <zhiguang.liu@intel.com>
>> ---
>>  MdePkg/Library/UefiFileHandleLib/UefiFileHandleLib.c | 6 ++++--
>>  1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/MdePkg/Library/UefiFileHandleLib/UefiFileHandleLib.c
>> b/MdePkg/Library/UefiFileHandleLib/UefiFileHandleLib.c
>> index 28e28e5f67d5..ab34e6ccd5f4 100644
>> --- a/MdePkg/Library/UefiFileHandleLib/UefiFileHandleLib.c
>> +++ b/MdePkg/Library/UefiFileHandleLib/UefiFileHandleLib.c
>> @@ -969,6 +969,7 @@ FileHandleReadLine(
>>    UINTN       CharSize;
>>
>>    UINTN       CountSoFar;
>>
>>    UINTN       CrCount;
>>
>> +  UINTN       OldSize;
>>
>>    UINT64      OriginalFilePosition;
>>
>>
>>
>>    if (Handle == NULL
>>
>> @@ -1039,10 +1040,11 @@ FileHandleReadLine(
>>    // if we ran out of space tell when...
>>
>>    //
>>
>>    if ((CountSoFar+1-CrCount)*sizeof(CHAR16) > *Size){
>>
>> +    OldSize = *Size;
>>
>>      *Size = (CountSoFar+1-CrCount)*sizeof(CHAR16);
>>
>>      if (!Truncate) {
>>
>> -      if (Buffer != NULL && *Size != 0) {
>>
>> -        ZeroMem(Buffer, *Size);
>>
>> +      if (Buffer != NULL && OldSize != 0) {
>>
>> +        ZeroMem(Buffer, OldSize);
>>
>>        }
>>
>>        FileHandleSetPosition(Handle, OriginalFilePosition);
>>
>>        return (EFI_BUFFER_TOO_SMALL);
>>
>> --
>> 2.26.2.266.ge870325ee8