Inline comment below:
From: Edwards, Craig <[email protected]> Sent: Thursday, January 6, 2022 2:53 AM To: Gao, Liming <[email protected]>; Wang, Jian J <[email protected]>; Wu, Hao A <[email protected]>; Ni, Ray <[email protected]>; Gao, Zhichao <[email protected]>; [email protected]; Shutt, Mark <[email protected]> Subject: [Patch MBR endless loop hang with invalid LBA0 1/1] MdeModulePkg/PartitionDxe: Add break to handle invalid LBA0 in MBR Read Disk does a modification of ExtMbrStartingLba with the code MultU64x32 (ExtMbrStartingLba, BlockSize) Error detection to see if ExtMbrStartingLBA has a value of 0. This is invalid as LBA 0 = MBR. After modification, the next time ExtMbrStartingLba is in this function if ExtMbrStartingLba is set to 0 in the MBR it never passes the while/do evaluation It is multiplied by 0 by read disk , set to 0 by an invalid MBR and goes back to evaluation This condition will also cause Ws19 and WS22 to hang, however Microsoft has developed a hotfix patch that will be released in 2022 Cc: Liming Gao <[email protected]<mailto:[email protected]>> Cc: Jian J Wang <[email protected]<mailto:[email protected]>> Cc: Hao A Wu <[email protected]<mailto:[email protected]>> Cc: Ray Ni <[email protected]<mailto:[email protected]>> Cc: Zhichao Gao <[email protected]<mailto:[email protected]>> Signed-off-by: Craig Edwards <[email protected]<mailto:[email protected]>> Date: Wed Jan 5 12:27:46 2022 -0600 On branch graceful_handle_mbr_hang_edit1 Changes to be committed: modified: MdeModulePkg/Universal/Disk/PartitionDxe/Mbr.c --- MdeModulePkg/Universal/Disk/PartitionDxe/Mbr.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/MdeModulePkg/Universal/Disk/PartitionDxe/Mbr.c b/MdeModulePkg/Universal/Disk/PartitionDxe/Mbr.c index 0f8dc5486521..ad18840e5efd 100644 --- a/MdeModulePkg/Universal/Disk/PartitionDxe/Mbr.c +++ b/MdeModulePkg/Universal/Disk/PartitionDxe/Mbr.c @@ -293,6 +293,12 @@ PartitionInstallMbrChildHandles ( (Mbr->Partition[0].OSIndicator == EXTENDED_WINDOWS_PARTITION)) { ExtMbrStartingLba = UNPACK_UINT32 (Mbr->Partition[0].StartingLBA); + // + // A value of 0 is invalid for StartingLBA + // + if (ExtMbrStartingLba == 0) { + break; + } Seems the indent includes 2 unneeded spaces. I will help to remove them when merging the patch. Reviewed-by: Hao A Wu <[email protected]> Will wait a couple of days before merging to see if comments from other reviewers. Best Regards, Hao Wu continue; } -- 2.32.0.windows.1 Craig Edwards Software Engineer Dell | GDP | PSE | COMMS | BIOS [email protected]<mailto:[email protected]%0d> Internal Use - Confidential -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#85295): https://edk2.groups.io/g/devel/message/85295 Mute This Topic: https://groups.io/mt/88220894/21656 Group Owner: [email protected] Unsubscribe: https://edk2.groups.io/g/devel/unsub [[email protected]] -=-=-=-=-=-=-=-=-=-=-=-
