5.5 - CVE-2024-56553

In the Linux kernel, the following vulnerability has been resolved:

binder: fix memleak of proc->delivered_freeze

If a freeze notification is cleared with BC_CLEAR_FREEZE_NOTIFICATION before calling binder_freeze_notification_done(), then it is detached from its reference (e.g. ref->freeze) but the work remains queued in proc->delivered_freeze. This leads to a memory leak when the process exits as any pending entries in proc->delivered_freeze are not freed:

unreferenced object 0xffff38e8cfa36180 (size 64):
comm "binder-util", pid 655, jiffies 4294936641
hex dump (first 32 bytes):
b8 e9 9e c8 e8 38 ff ff b8 e9 9e c8 e8 38 ff ff .....8.......8..
0b 00 00 00 00 00 00 00 3c 1f 4b 00 00 00 00 00 ........<.K.....
backtrace (crc 95983b32):
[<000000000d0582cf>] kmemleak_alloc+0x34/0x40
[<000000009c99a513>] __kmalloc_cache_noprof+0x208/0x280
[<00000000313b1704>] binder_thread_write+0xdec/0x439c
[<000000000cbd33bb>] binder_ioctl+0x1b68/0x22cc
[<000000002bbedeeb>] __arm64_sys_ioctl+0x124/0x190
[<00000000b439adee>] invoke_syscall+0x6c/0x254
[<00000000173558fc>] el0_svc_common.constprop.0+0xac/0x230
[<0000000084f72311>] do_el0_svc+0x40/0x58
[<000000008b872457>] el0_svc+0x38/0x78
[<00000000ee778653>] el0t_64_sync_handler+0x120/0x12c
[<00000000a8ec61bf>] el0t_64_sync+0x190/0x194

This patch fixes the leak by ensuring that any pending entries in proc->delivered_freeze are freed during binder_deferred_release().