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coverity/331378: Fix inserting new decor provider

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Since the providers are ordered by ns_id, inserting a new provider may
require shifting existing providers around to maintain this ordering.

When this happens, we need to allocate a new element at the end of the
vector and then shift the larger elements to the right.  Rather than
iterating (incorrectly) with a loop and copying each item, use memmove
to copy the entire block.
This commit is contained in:
James McCoy 2021-05-05 21:26:51 -04:00
parent 71107e12c7
commit 833a6fcb60
No known key found for this signature in database
GPG Key ID: DFE691AE331BA3DB
2 changed files with 24 additions and 7 deletions
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19
src/nvim/decoration.c
View File

@ -383,8 +383,9 @@ void decor_add_ephemeral(int start_row, int start_col, int end_row, int end_col,
DecorProvider *get_decor_provider(NS ns_id, bool force)
{
ssize_t i;
for (i = 0; i < (ssize_t)kv_size(decor_providers); i++) {
size_t i;
size_t len = kv_size(decor_providers);
for (i = 0; i < len; i++) {
DecorProvider *item = &kv_A(decor_providers, i);
if (item->ns_id == ns_id) {
return item;
@ -397,12 +398,16 @@ DecorProvider *get_decor_provider(NS ns_id, bool force)
return NULL;
}
for (ssize_t j = (ssize_t)kv_size(decor_providers)-1; j >= i; j++) {
// allocates if needed:
(void)kv_a(decor_providers, (size_t)j+1);
kv_A(decor_providers, (size_t)j+1) = kv_A(decor_providers, j);
// Adding a new provider, so allocate room in the vector
(void)kv_a(decor_providers, len);
if (i < len) {
// New ns_id needs to be inserted between existing providers to maintain
// ordering, so shift other providers with larger ns_id
memmove(&kv_A(decor_providers, i + 1),
&kv_A(decor_providers, i),
(len - i) * sizeof(kv_a(decor_providers, i)));
}
DecorProvider *item = &kv_a(decor_providers, (size_t)i);
DecorProvider *item = &kv_a(decor_providers, i);
*item = DECORATION_PROVIDER_INIT(ns_id);
return item;

12
test/functional/ui/decorations_spec.lua
View File

@ -66,6 +66,18 @@ describe('decorations providers', function()
expect_events(expected, actual, "beam trace")
end
it('does not OOM when inserting, rather than appending, to the decoration provider vector', function()
-- Add a dummy decoration provider with a larger ns id than what setup_provider() creates.
-- This forces get_decor_provider() to insert into the providers vector,
-- rather than append, which used to spin in an infinite loop allocating
-- memory until nvim crashed/was killed.
setup_provider([[
local ns2 = a.nvim_create_namespace "ns2"
a.nvim_set_decoration_provider(ns2, {})
]])
helpers.assert_alive()
end)
it('leave a trace', function()
insert(mulholland)