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Fix undefined behavior in key_from_id() #129420

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Fix undefined behavior in key_from_id() #129420

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225b0d2
Fix signed type extension_offset check in key_from_id()
dovydenkovas Jun 15, 2026
0ae724c
Replace null check with assert in `key_from_id()`
dovydenkovas Jun 15, 2026
cddb6b0
Ensure resource id is not null in bundled_resources_get
dovydenkovas Jun 15, 2026
5096eab
Merge branch 'main' into fix-key_from_id-UB
lewing Jul 18, 2026
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26 changes: 18 additions & 8 deletions src/mono/mono/metadata/bundled-resources.c
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Original file line number Diff line number Diff line change
Expand Up @@ -75,19 +75,29 @@ bundled_resources_is_known_assembly_extension (const char *ext)

// If a bundled resource has a known assembly extension, we strip the extension from its name
// This ensures that lookups for foo.dll will work even if the assembly is in a webcil container
//
// Arguments:
// * id - Name of the resource, not NULL, null-terminated byte string.
// * buffer - Data to be written at given target address.
// * buffer_len - Length of buffer.
//
// Returns:
// static char * - Pointer to the stripped name of the resource.
//

static char *
key_from_id (const char *id, char *buffer, guint buffer_len)
{
size_t id_length = 0;
size_t extension_offset = -1;
ssize_t extension_offset = -1;
const char *extension = NULL;

if (id){
id_length = strlen (id);
extension = g_memrchr (id, '.', id_length);
if (extension)
extension_offset = extension - id;
}
g_assert (id);

@github-actions github-actions Bot Jul 19, 2026

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💡 Trailing whitespace: this line ends with a stray tab after g_assert (id);. There is also trailing whitespace on the new comment line 78 (// ) and the tab-only line 100. Please strip these to keep the file clean and avoid tripping format/whitespace checks.

id_length = strlen (id);
extension = g_memrchr (id, '.', id_length);
if (extension)
extension_offset = extension - id;

if (!buffer) {
// Add space for .dll and null terminator
buffer_len = (guint)(id_length + 6);
Expand Down Expand Up @@ -198,7 +208,7 @@ mono_bundled_resources_add (MonoBundledResource **resources_to_bundle, uint32_t
static MonoBundledResource *
bundled_resources_get (const char *id)
{
if (!bundled_resources)
if (!bundled_resources || !id)
return NULL;

char key_buffer[1024];
Expand Down