Hi Vladimir
Thanks for catching this bug. And I agree with you about your code change.
One little problem is that we always define the variable in the beginning of
the function.
Please fix the little issue and I will give my RB.
Thanks
Zhiguang
> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Vladimir
> Olovyannikov via groups.io
> Sent: Friday, June 5, 2020 8:18 AM
> To: devel@edk2.groups.io
> Cc: Vladimir Olovyannikov <vladimir.olovyanni...@broadcom.com>; Kinney,
> Michael D <michael.d.kin...@intel.com>; Gao, Liming
> <liming....@intel.com>
> Subject: [edk2-devel] [PATCH v1 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.olovyanni...@broadcom.com>
> Cc: Michael D Kinney <michael.d.kin...@intel.com>
> Cc: Liming Gao <liming....@intel.com>
> ---
> MdePkg/Library/UefiFileHandleLib/UefiFileHandleLib.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/MdePkg/Library/UefiFileHandleLib/UefiFileHandleLib.c
> b/MdePkg/Library/UefiFileHandleLib/UefiFileHandleLib.c
> index 28e28e5f67d5..4bc9fabb6c74 100644
> --- a/MdePkg/Library/UefiFileHandleLib/UefiFileHandleLib.c
> +++ b/MdePkg/Library/UefiFileHandleLib/UefiFileHandleLib.c
> @@ -1039,10 +1039,13 @@ FileHandleReadLine(
> // if we ran out of space tell when...
>
> //
>
> if ((CountSoFar+1-CrCount)*sizeof(CHAR16) > *Size){
>
> + UINTN OldSize;
>
> +
>
> + 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
>
>
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> [zhiguang....@intel.com]
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