tree a9cc42a695f26db2fee2fa03fe1749bacd5cefb8
parent dc4060a5dc2557e6b5aa813bf5b73677299d62d2
author Brian Foster <bfoster@redhat.com> 1555079959 -0700
committer Darrick J. Wong <darrick.wong@oracle.com> 1555290956 -0700

xfs: fix use after free in buf log item unlock assert

The xfs_buf_log_item ->iop_unlock() callback asserts that the buffer
is unlocked when either non-stale or aborted. This assert occurs
after the bli refcount has been dropped and the log item potentially
freed. The aborted check is thus a potential use after free. This
problem has been reproduced with KASAN enabled via generic/475.

Fix up xfs_buf_item_unlock() to query aborted state before the bli
reference is dropped to prevent a potential use after free.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>