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ANDROID: fuzz: Only check valid phandles

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Ignore invalid phandles from fdt_get_phandle().

Update the assert() to avoid false positives, as per the libfdt API:
```
 * fdt_node_offset_by_phandle() returns the offset of the node
 * which has the given phandle value.  If there is more than one node
 * in the tree with the given phandle (an invalid tree), results are
 * undefined.
```

Bug: 240612647
Test: SANITIZE_HOST=address m libfdt_fuzzer
Signed-off-by: Pierre-Clément Tosi <ptosi@google.com>
Change-Id: Ifbb6a25ab6bd1463afccc88f9756d34c3cf59717
This commit is contained in:
Pierre-Clément Tosi 2022-07-26 15:59:06 +01:00
parent f500e27127
commit 3afda967bc
1 changed files with 6 additions and 2 deletions
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8
fuzzing/libfdt_fuzzer.c
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@ -55,6 +55,9 @@ static void check_mem(const void *mem, size_t len) {
#endif
}
static bool phandle_is_valid(uint32_t phandle) {
return phandle != 0 && phandle != UINT32_MAX;
}
static void walk_device_tree(const void *device_tree, int parent_node) {
int len = 0;
@ -64,8 +67,9 @@ static void walk_device_tree(const void *device_tree, int parent_node) {
}
uint32_t phandle = fdt_get_phandle(device_tree, parent_node);
if (phandle != 0) {
assert(parent_node == fdt_node_offset_by_phandle(device_tree, phandle));
if (phandle_is_valid(phandle)) {
int node = fdt_node_offset_by_phandle(device_tree, phandle);
assert(node >= 0); // it should at least find parent_node
}
// recursively walk the node's children