From: Alex Williamson Date: Mon, 2 Oct 2023 22:43:25 +0000 (-0600) Subject: vfio: Fix smatch errors in vfio_combine_iova_ranges() X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=bd885fcf28da7da6a2244d30cd45630303c781ed;p=linux.git vfio: Fix smatch errors in vfio_combine_iova_ranges() smatch reports: vfio_combine_iova_ranges() error: uninitialized symbol 'last'. vfio_combine_iova_ranges() error: potentially dereferencing uninitialized 'comb_end'. vfio_combine_iova_ranges() error: potentially dereferencing uninitialized 'comb_start'. These errors are only reachable via invalid input, in the case of @last when we receive an empty rb-tree or for @comb_{start,end} if the rb-tree is empty or otherwise fails to produce a second node that reduces the gap. Add tests with warnings for these cases. Reported-by: Cong Liu Link: https://lore.kernel.org/all/20230920095532.88135-1-liucong2@kylinos.cn Reviewed-by: Jason Gunthorpe Reviewed-by: Brett Creeley Link: https://lore.kernel.org/r/20231002224325.3150842-1-alex.williamson@redhat.com Signed-off-by: Alex Williamson --- diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c index 40732e8ed4c6f..e31e1952d7b8f 100644 --- a/drivers/vfio/vfio_main.c +++ b/drivers/vfio/vfio_main.c @@ -946,6 +946,11 @@ void vfio_combine_iova_ranges(struct rb_root_cached *root, u32 cur_nodes, unsigned long last; comb_start = interval_tree_iter_first(root, 0, ULONG_MAX); + + /* Empty list */ + if (WARN_ON_ONCE(!comb_start)) + return; + curr = comb_start; while (curr) { last = curr->last; @@ -975,6 +980,11 @@ void vfio_combine_iova_ranges(struct rb_root_cached *root, u32 cur_nodes, prev = curr; curr = interval_tree_iter_next(curr, 0, ULONG_MAX); } + + /* Empty list or no nodes to combine */ + if (WARN_ON_ONCE(min_gap == ULONG_MAX)) + break; + comb_start->last = comb_end->last; interval_tree_remove(comb_end, root); cur_nodes--;