During the update process in sa_modify_attrs(), the sizes of existing
variably-sized SA entries are obtained from sa_lengths[]. The case where
a variably-sized SA was being replaced neglected to increment the index
into sa_lengths[], so subsequent variable-length SAs would be rewritten
with the wrong length. This patch adds the missing increment operation
so all variably-sized SA entries are stored with their correct lengths.
Previously, a size-changing update of a variably-sized SA that occurred
when there were other variably-sized SAs in the bonus buffer would cause
the subsequent SAs to be corrupted. The most common case in which this
would occur is when a mode change caused the ZPL_DACL_ACES entry to
change size when a ZPL_DXATTR (SA xattr) entry already existed.
The following sequence would have caused a failure when xattr=sa was in
force and would corrupt the bonus buffer. This is a long standing issue
but it was exposed under Linux and FreeBSD where the use of multiple
variable length SAs is common.
open(filename, O_WRONLY | O_CREAT, 0600);
...
lsetxattr(filename, ...); /* create xattr SA */
chmod(filename, 0650); /* enlarges the ACL */
zfsonlinux/zfs#1978
Signed-off-by: Chris Dunlop <[email protected]>
Signed-off-by: Ned Bass <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
You can view, comment on, or merge this pull request online at:
https://github.com/openzfs/openzfs/pull/24
-- Commit Summary --
* Properly handle updates of variably-sized SA entries.
-- File Changes --
M usr/src/uts/common/fs/zfs/sa.c (17)
-- Patch Links --
https://github.com/openzfs/openzfs/pull/24.patch
https://github.com/openzfs/openzfs/pull/24.diff
---
Reply to this email directly or view it on GitHub:
https://github.com/openzfs/openzfs/pull/24
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