|
 |
468bd4 |
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
|
|
|
468bd4 |
From: Darren Kenny <darren.kenny@oracle.com>
|
|
|
468bd4 |
Date: Tue, 24 Nov 2020 16:41:49 +0000
|
|
|
468bd4 |
Subject: [PATCH] zfs: Fix possible negative shift operation
|
|
|
468bd4 |
|
|
|
468bd4 |
While it is possible for the return value from zfs_log2() to be zero
|
|
|
468bd4 |
(0), it is quite unlikely, given that the previous assignment to blksz
|
|
|
468bd4 |
is shifted up by SPA_MINBLOCKSHIFT (9) before 9 is subtracted at the
|
|
|
468bd4 |
assignment to epbs.
|
|
|
468bd4 |
|
|
|
468bd4 |
But, while unlikely during a normal operation, it may be that a carefully
|
|
|
468bd4 |
crafted ZFS filesystem could result in a zero (0) value to the
|
|
|
468bd4 |
dn_datalbkszsec field, which means that the shift left does nothing
|
|
|
468bd4 |
and assigns zero (0) to blksz, resulting in a negative epbs value.
|
|
|
468bd4 |
|
|
|
468bd4 |
Fixes: CID 73608
|
|
|
468bd4 |
|
|
|
468bd4 |
Signed-off-by: Darren Kenny <darren.kenny@oracle.com>
|
|
|
468bd4 |
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
|
|
|
468bd4 |
---
|
|
|
468bd4 |
grub-core/fs/zfs/zfs.c | 5 +++++
|
|
|
468bd4 |
1 file changed, 5 insertions(+)
|
|
|
468bd4 |
|
|
|
468bd4 |
diff --git a/grub-core/fs/zfs/zfs.c b/grub-core/fs/zfs/zfs.c
|
|
|
468bd4 |
index c6204367e78..3dfde080750 100644
|
|
|
468bd4 |
--- a/grub-core/fs/zfs/zfs.c
|
|
|
468bd4 |
+++ b/grub-core/fs/zfs/zfs.c
|
|
|
468bd4 |
@@ -2667,6 +2667,11 @@ dnode_get (dnode_end_t * mdn, grub_uint64_t objnum, grub_uint8_t type,
|
|
|
468bd4 |
blksz = grub_zfs_to_cpu16 (mdn->dn.dn_datablkszsec,
|
|
|
468bd4 |
mdn->endian) << SPA_MINBLOCKSHIFT;
|
|
|
468bd4 |
epbs = zfs_log2 (blksz) - DNODE_SHIFT;
|
|
|
468bd4 |
+
|
|
|
468bd4 |
+ /* While this should never happen, we should check that epbs is not negative. */
|
|
|
468bd4 |
+ if (epbs < 0)
|
|
|
468bd4 |
+ epbs = 0;
|
|
|
468bd4 |
+
|
|
|
468bd4 |
blkid = objnum >> epbs;
|
|
|
468bd4 |
idx = objnum & ((1 << epbs) - 1);
|
|
|
468bd4 |
|