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vfio: Fix smatch errors in vfio_combine_iova_ranges()

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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 <liucong2@kylinos.cn>
Link: https://lore.kernel.org/all/20230920095532.88135-1-liucong2@kylinos.cn
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Brett Creeley <brett.creeley@amd.com>
Link: https://lore.kernel.org/r/20231002224325.3150842-1-alex.williamson@redhat.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Alex Williamson 2023-10-02 16:43:25 -06:00
parent f9af5ad0f5
commit bd885fcf28
1 changed files with 10 additions and 0 deletions
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10
drivers/vfio/vfio_main.c
View file

@ -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--;