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MdeModulePkg/UdfDxe: Fix NULL pointer dereference 

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=704

For root directory, the FID (File Identifier Descriptor) pointer is
accessible through PRIVATE_UDF_FILE_DATA.Root, whereas non-root
directory and regular files, their FIDs are accessible through
PRIVATE_UDF_FILE_DATA.File.

In UdfSetPosition(), the FID was retrieved through
PRIVATE_UDF_FILE_DATA.File, hence when calling it with a root directory,
PRIVATE_UDF_FILE_DATA.File.FileIdentifierDescriptor would be NULL and
then dereferenced.

This patch fixes the NULL pointer dereference by calling _FILE() to
transparently return the correct UDF_FILE_INFO * which points to a valid
FID descriptor of a specific file.

Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Steven Shi <steven.shi@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Reported-by: Steven Shi <steven.shi@intel.com>
Signed-off-by: Paulo Alcantara <pcacjr@zytor.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>
This commit is contained in:
Paulo Alcantara 2017-09-12 09:30:23 +08:00 committed by Star Zeng
parent 54537008a2
commit 11b4463e09
1 changed files with 2 additions and 1 deletions
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3
MdeModulePkg/Universal/Disk/UdfDxe/File.c
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@ -692,7 +692,8 @@ UdfSetPosition (
PrivFileData = PRIVATE_UDF_FILE_DATA_FROM_THIS (This); PrivFileData = PRIVATE_UDF_FILE_DATA_FROM_THIS (This);
FileIdentifierDesc = PrivFileData->File.FileIdentifierDesc; FileIdentifierDesc = _FILE (PrivFileData)->FileIdentifierDesc;
ASSERT (FileIdentifierDesc != NULL);
if (IS_FID_DIRECTORY_FILE (FileIdentifierDesc)) { if (IS_FID_DIRECTORY_FILE (FileIdentifierDesc)) {
// //
// If the file handle is a directory, the _only_ position that may be set is // If the file handle is a directory, the _only_ position that may be set is