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linux/drivers/android
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Carlos Llamas c301ec61ce binder: fix double-free in dbitmap 
commit 3ebcd3460c upstream.

A process might fail to allocate a new bitmap when trying to expand its
proc->dmap. In that case, dbitmap_grow() fails and frees the old bitmap
via dbitmap_free(). However, the driver calls dbitmap_free() again when
the same process terminates, leading to a double-free error:

  ==================================================================
  BUG: KASAN: double-free in binder_proc_dec_tmpref+0x2e0/0x55c
  Free of addr ffff00000b7c1420 by task kworker/9:1/209

  CPU: 9 UID: 0 PID: 209 Comm: kworker/9:1 Not tainted 6.17.0-rc6-dirty #5 PREEMPT
  Hardware name: linux,dummy-virt (DT)
  Workqueue: events binder_deferred_func
  Call trace:
   kfree+0x164/0x31c
   binder_proc_dec_tmpref+0x2e0/0x55c
   binder_deferred_func+0xc24/0x1120
   process_one_work+0x520/0xba4
  [...]

  Allocated by task 448:
   __kmalloc_noprof+0x178/0x3c0
   bitmap_zalloc+0x24/0x30
   binder_open+0x14c/0xc10
  [...]

  Freed by task 449:
   kfree+0x184/0x31c
   binder_inc_ref_for_node+0xb44/0xe44
   binder_transaction+0x29b4/0x7fbc
   binder_thread_write+0x1708/0x442c
   binder_ioctl+0x1b50/0x2900
  [...]
  ==================================================================

Fix this issue by marking proc->map NULL in dbitmap_free().

Cc: stable@vger.kernel.org
Fixes: 15d9da3f81 ("binder: use bitmap for faster descriptor lookup")
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Tiffany Yang <ynaffit@google.com>
Link: https://lore.kernel.org/r/20250915221248.3470154-1-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2025-10-12 12:57:18 +02:00
..
binder.c binder: fix offset calculation in debug log 2025-05-09 09:50:29 +02:00
binder_alloc.c binder_alloc: Fix sleeping function called from invalid context 2024-07-31 13:48:25 +02:00
binder_alloc.h binder: switch alloc->mutex to spinlock_t 2023-12-05 09:23:41 +09:00
binder_alloc_selftest.c android: binder: fix a kernel-doc enum warning 2023-12-06 08:48:26 +09:00
binder_internal.h binder: frozen notification 2024-07-31 13:56:00 +02:00
binder_trace.h binder: keep vma addresses type as unsigned long 2023-12-05 09:23:38 +09:00
binderfs.c binder: frozen notification binder_features flag 2024-07-31 13:56:00 +02:00
dbitmap.h binder: fix double-free in dbitmap 2025-10-12 12:57:18 +02:00
Kconfig remove CONFIG_ANDROID 2022-07-01 10:41:09 +02:00
Makefile treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00