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MdeModulePkg/UdfDxe: Avoid possible loss track of allocated buffer 

In function FindFileEntry():

Instead of using the function parameter 'FileEntry', use a local
variable to store the buffer allocated for disk read operation.

For the below calling stack:
UdfOpenVolume() -> FindRootDirectory() -> FindFileEntry()

In FindFileEntry(), the call to 'DiskIo->ReadDisk()' is possible (e.g.
media change for a CD/DVD ROM device) to trigger a re-install of the
BlockIO(2) protocol which will further lead to a call of the BindingStop()
& BingdingStart() of the UdfDxe driver.

Meanwhile, for the above listed calling stack, the '**FileEntry'
parameter passed into FindFileEntry() is '&PrivFsData->Root'. 'PrivFsData'
is a driver-managed private data, it will be freed in BindingStop() and
re-allocate in BingdingStart().

In such case, if '*FileEntry' is used to store the allocated buffer, the
information will be lost if 'DiskIo->ReadDisk()' triggers a re-install of
the BlockIO(2) protocol. The subsequent call of the FreePool API:

FreePool (*FileEntry);

will cause issues.

This commit uses a local variable to store the allocated buffer.

Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Paulo Alcantara <pcacjr@zytor.com>
This commit is contained in:
Hao Wu 2017-11-14 11:33:10 +08:00
parent 01a68fd37e
commit 7a96634889
1 changed files with 7 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
MdeModulePkg/Universal/Disk/UdfDxe/FileSystemOperations.c
View File

@ -1615,12 +1615,13 @@ FindFileEntry (
UINT64 Lsn;
UINT32 LogicalBlockSize;
UDF_DESCRIPTOR_TAG *DescriptorTag;
VOID *ReadBuffer;
Lsn = GetLongAdLsn (Volume, Icb);
LogicalBlockSize = Volume->LogicalVolDesc.LogicalBlockSize;
*FileEntry = AllocateZeroPool (Volume->FileEntrySize);
if (*FileEntry == NULL) {
ReadBuffer = AllocateZeroPool (Volume->FileEntrySize);
if (ReadBuffer == NULL) {
return EFI_OUT_OF_RESOURCES;
}
@ -1632,13 +1633,13 @@ FindFileEntry (
BlockIo->Media->MediaId,
MultU64x32 (Lsn, LogicalBlockSize),
Volume->FileEntrySize,
*FileEntry
ReadBuffer
);
if (EFI_ERROR (Status)) {
goto Error_Read_Disk_Blk;
}
DescriptorTag = *FileEntry;
DescriptorTag = ReadBuffer;
//
// Check if the read extent contains a valid Tag Identifier for the expected
@ -1650,11 +1651,12 @@ FindFileEntry (
goto Error_Invalid_Fe;
}
*FileEntry = ReadBuffer;
return EFI_SUCCESS;
Error_Invalid_Fe:
Error_Read_Disk_Blk:
FreePool (*FileEntry);
FreePool (ReadBuffer);
return Status;
}