| From a02091834d3e167320d8a262ff04b8e83c5e616d Mon Sep 17 00:00:00 2001 |
| From: Darren Kenny <darren.kenny@oracle.com> |
| Date: Tue, 24 Nov 2020 16:41:49 +0000 |
| Subject: [PATCH] zfs: Fix possible negative shift operation |
| |
| While it is possible for the return value from zfs_log2() to be zero |
| (0), it is quite unlikely, given that the previous assignment to blksz |
| is shifted up by SPA_MINBLOCKSHIFT (9) before 9 is subtracted at the |
| assignment to epbs. |
| |
| But, while unlikely during a normal operation, it may be that a carefully |
| crafted ZFS filesystem could result in a zero (0) value to the |
| dn_datalbkszsec field, which means that the shift left does nothing |
| and assigns zero (0) to blksz, resulting in a negative epbs value. |
| |
| Fixes: CID 73608 |
| |
| Signed-off-by: Darren Kenny <darren.kenny@oracle.com> |
| Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com> |
| Signed-off-by: Stefan SΓΈrensen <stefan.sorensen@spectralink.com> |
| --- |
| grub-core/fs/zfs/zfs.c | 5 +++++ |
| 1 file changed, 5 insertions(+) |
| |
| diff --git a/grub-core/fs/zfs/zfs.c b/grub-core/fs/zfs/zfs.c |
| index 36d0373..0c42cba 100644 |
| --- a/grub-core/fs/zfs/zfs.c |
| +++ b/grub-core/fs/zfs/zfs.c |
| @@ -2667,6 +2667,11 @@ dnode_get (dnode_end_t * mdn, grub_uint64_t objnum, grub_uint8_t type, |
| blksz = grub_zfs_to_cpu16 (mdn->dn.dn_datablkszsec, |
| mdn->endian) << SPA_MINBLOCKSHIFT; |
| epbs = zfs_log2 (blksz) - DNODE_SHIFT; |
| + |
| + /* While this should never happen, we should check that epbs is not negative. */ |
| + if (epbs < 0) |
| + epbs = 0; |
| + |
| blkid = objnum >> epbs; |
| idx = objnum & ((1 << epbs) - 1); |
| |
| -- |
| 2.14.2 |
| |