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kernel: userspace: manipulate _thread_idx_map on per-byte basis

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The sys_bitfield_(clear/set)_bit() work on pointer size element.
However, _thread_idx_map[] is a byte array. On little endian
systems, the bitops should work fine. However, on big endian
systems, changing the lower bits may actually be manipulating
memory outside the array when CONFIG_MAX_THREAD_BYTES is not
multiple of 4. So modify the code to perform bit ops on
a per-byte basis.

Fixes #72430

Signed-off-by: Daniel Leung <daniel.leung@intel.com>
This commit is contained in:
Daniel Leung 2024-05-14 16:16:10 -07:00 • committed by Johan Hedberg
commit 2ad265cb75
1 changed files with 9 additions and 3 deletions
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12
kernel/userspace.c
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@ -277,8 +277,10 @@ static bool thread_idx_alloc(uintptr_t *tidx)
if (idx != 0) {
*tidx = base + (idx - 1);
sys_bitfield_clear_bit((mem_addr_t)_thread_idx_map,
*tidx);
/* Clear the bit. We already know the array index,
* and the bit to be cleared.
*/
_thread_idx_map[i] &= ~(BIT(idx - 1));
/* Clear permission from all objects */
k_object_wordlist_foreach(clear_perms_cb,
@ -308,7 +310,11 @@ static void thread_idx_free(uintptr_t tidx)
/* To prevent leaked permission when index is recycled */
k_object_wordlist_foreach(clear_perms_cb, (void *)tidx);
sys_bitfield_set_bit((mem_addr_t)_thread_idx_map, tidx);
/* Figure out which bits to set in _thread_idx_map[] and set it. */
int base = tidx / NUM_BITS(_thread_idx_map[0]);
int offset = tidx % NUM_BITS(_thread_idx_map[0]);
_thread_idx_map[base] |= BIT(offset);
}
static struct k_object *dynamic_object_create(enum k_objects otype, size_t align,