[XFS] Fix an inode use-after-free durin an unpin. When reclaiming inodes (58829e49) · Commits · 戴 / test

that have been unlinked, we may need to execute transactions during reclaim. By the time the transaction has hit the disk, the linux inode and xfs vnode may already have been freed so we can't reference them safely. Use the known xfs inode state to determine if it is safe to reference the vnode and linux inode during the unpin operation. SGI-PV: 946321 SGI-Modid: xfs-linux-melb:xfs-kern:25687a Signed-off-by:

David Chinner <dgc@sgi.com> Signed-off-by:

Nathan Scott <nathans@sgi.com>

fs/xfs/xfs_inode.c

+20 −7

Original line number	Diff line number	Diff line
		@@ -2732,6 +2732,19 @@ xfs_iunpin(
		ASSERT(atomic_read(&ip->i_pincount) > 0);

		if (atomic_dec_and_test(&ip->i_pincount)) {
		/*
		* If the inode is currently being reclaimed, the
		* linux inode _and_ the xfs vnode may have been
		* freed so we cannot reference either of them safely.
		* Hence we should not try to do anything to them
		* if the xfs inode is currently in the reclaim
		* path.
		*
		* However, we still need to issue the unpin wakeup
		* call as the inode reclaim may be blocked waiting for
		* the inode to become unpinned.
		*/
		if (!(ip->i_flags & (XFS_IRECLAIM\|XFS_IRECLAIMABLE))) {
		vnode_t *vp = XFS_ITOV_NULL(ip);

		/* make sync come back and flush this inode */
		@@ -2741,7 +2754,7 @@ xfs_iunpin(
		if (!(inode->i_state & I_NEW))
		mark_inode_dirty_sync(inode);
		}

		}
		wake_up(&ip->i_ipin_wait);
		}
		}

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