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@xxxxxxxxxx> --- fs/xfs/xfs_buf_item.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c index 010db5f8fb00..65b32acfa0f6 100644 --- a/fs/xfs/xfs_buf_item.c +++ b/fs/xfs/xfs_buf_item.c @@ -605,6 +605,8 @@ xfs_buf_item_unlock( #if defined(DEBUG) || defined(XFS_WARN) bool ordered = bip->bli_flags & XFS_BLI_ORDERED; bool dirty = bip->bli_flags & XFS_BLI_DIRTY; + bool aborted = test_bit(XFS_LI_ABORTED, + &lip->li_flags); #endif trace_xfs_buf_item_unlock(bip); @@ -633,7 +635,7 @@ xfs_buf_item_unlock( released = xfs_buf_item_put(bip); if (hold || (stale && !released)) return; - ASSERT(!stale || test_bit(XFS_LI_ABORTED, &lip->li_flags)); + ASSERT(!stale || aborted); xfs_buf_relse(bp); } -- 2.17.2
