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Fixed invalid memory read/segfault #2379

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Merged
merged 1 commit into from
Apr 9, 2025
Merged

Fixed invalid memory read/segfault #2379

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18 changes: 12 additions & 6 deletions src/context.c
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Original file line number Diff line number Diff line change
Expand Up @@ -272,9 +272,9 @@ ly_ctx_ht_err_equal_cb(void *val1_p, void *val2_p, ly_bool UNUSED(mod), void *UN
static ly_bool
ly_ctx_ht_leafref_links_equal_cb(void *val1_p, void *val2_p, ly_bool UNUSED(mod), void *UNUSED(cb_data))
{
struct lyd_leafref_links_rec *rec1 = val1_p, *rec2 = val2_p;
struct lyd_leafref_links_rec **rec1 = val1_p, **rec2 = val2_p;

return rec1->node == rec2->node;
return (*rec1)->node == (*rec2)->node;
}

/**
Expand All @@ -285,9 +285,10 @@ ly_ctx_ht_leafref_links_equal_cb(void *val1_p, void *val2_p, ly_bool UNUSED(mod)
static void
ly_ctx_ht_leafref_links_rec_free(void *val_p)
{
struct lyd_leafref_links_rec *rec = val_p;
struct lyd_leafref_links_rec **rec = val_p;

lyd_free_leafref_links_rec(rec);
lyd_free_leafref_links_rec(*rec);
free(*rec);
}

LIBYANG_API_DEF LY_ERR
Expand Down Expand Up @@ -316,7 +317,12 @@ ly_ctx_new(const char *search_dir, uint16_t options, struct ly_ctx **new_ctx)
LY_CHECK_ERR_GOTO(lyplg_init(builtin_plugins_only), LOGINT(NULL); rc = LY_EINT, cleanup);

if (options & LY_CTX_LEAFREF_LINKING) {
ctx->leafref_links_ht = lyht_new(1, sizeof(struct lyd_leafref_links_rec), ly_ctx_ht_leafref_links_equal_cb, NULL, 1);
/**
* storing the pointer instead of record itself is needed to avoid invalid memory reads. Hash table can reallocate
* its memory completely during various manipulation function (e.g. remove, insert). In case of using pointers, the
* pointer can be reallocated safely, while record itself remains untouched and can be accessed/modified freely
* */
ctx->leafref_links_ht = lyht_new(1, sizeof(struct lyd_leafref_links_rec *), ly_ctx_ht_leafref_links_equal_cb, NULL, 1);
LY_CHECK_ERR_GOTO(!ctx->leafref_links_ht, rc = LY_EMEM, cleanup);
}

Expand Down Expand Up @@ -654,7 +660,7 @@ ly_ctx_set_options(struct ly_ctx *ctx, uint16_t option)
}

if (!(ctx->flags & LY_CTX_LEAFREF_LINKING) && (option & LY_CTX_LEAFREF_LINKING)) {
ctx->leafref_links_ht = lyht_new(1, sizeof(struct lyd_leafref_links_rec), ly_ctx_ht_leafref_links_equal_cb, NULL, 1);
ctx->leafref_links_ht = lyht_new(1, sizeof(struct lyd_leafref_links_rec *), ly_ctx_ht_leafref_links_equal_cb, NULL, 1);
LY_CHECK_ERR_RET(!ctx->leafref_links_ht, LOGARG(ctx, option), LY_EMEM);
}

Expand Down
17 changes: 14 additions & 3 deletions src/tree_data.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3610,8 +3610,11 @@ LY_ERR
lyd_get_or_create_leafref_links_record(const struct lyd_node_term *node, struct lyd_leafref_links_rec **record, ly_bool create)
{
struct ly_ht *ht;
LY_ERR ret = LY_SUCCESS;
uint32_t hash;
struct lyd_leafref_links_rec rec = {0};
struct lyd_leafref_links_rec *rec_p = &rec;
struct lyd_leafref_links_rec **rec_p2;

assert(node);
assert(record);
Expand All @@ -3626,15 +3629,23 @@ lyd_get_or_create_leafref_links_record(const struct lyd_node_term *node, struct
ht = LYD_CTX(node)->leafref_links_ht;
hash = lyht_hash((const char *)&node, sizeof node);

if (lyht_find(ht, &rec, hash, (void **)record) == LY_ENOTFOUND) {
if (lyht_find(ht, &rec_p, hash, (void **)&rec_p2) == LY_ENOTFOUND) {
if (create) {
LY_CHECK_RET(lyht_insert_no_check(ht, &rec, hash, (void **)record));
rec_p = calloc(1, sizeof rec);
rec_p->node = node;
LY_CHECK_ERR_RET(!rec_p, LOGMEM(LYD_CTX(node)), LY_EMEM);
ret = lyht_insert_no_check(ht, &rec_p, hash, (void **)&rec_p2);
LY_CHECK_ERR_GOTO(ret, free(rec_p), cleanup);
} else {
return LY_ENOTFOUND;
}
}

return LY_SUCCESS;
cleanup:
if (!ret) {
*record = *rec_p2;
}
return ret;
}

LIBYANG_API_DEF LY_ERR
Expand Down
3 changes: 2 additions & 1 deletion src/tree_data_free.c
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Original file line number Diff line number Diff line change
Expand Up @@ -191,7 +191,8 @@ lyd_free_leafref_nodes(const struct lyd_node_term *node)
/* free entry itself from hash table */
ht = LYD_CTX(node)->leafref_links_ht;
hash = lyht_hash((const char *)&node, sizeof node);
lyht_remove(ht, rec, hash);
lyht_remove(ht, &rec, hash);
free(rec);
}

/**
Expand Down