Carlos Llamas 11512c197d binder: fix descriptor lookup for context manager ... In commit 15d9da3f81 ("binder: use bitmap for faster descriptor lookup"), it was incorrectly assumed that references to the context manager node should always get descriptor zero assigned to them. However, if the context manager dies and a new process takes its place, then assigning descriptor zero to the new context manager might lead to collisions, as there could still be references to the older node. This issue was reported by syzbot with the following trace: kernel BUG at drivers/android/binder.c:1173! Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP Modules linked in: CPU: 1 PID: 447 Comm: binder-util Not tainted 6.10.0-rc6-00348-g31643d84b8c3 #10 Hardware name: linux,dummy-virt (DT) pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : binder_inc_ref_for_node+0x500/0x544 lr : binder_inc_ref_for_node+0x1e4/0x544 sp : ffff80008112b940 x29: ffff80008112b940 x28: ffff0e0e40310780 x27: 0000000000000000 x26: 0000000000000001 x25: ffff0e0e40310738 x24: ffff0e0e4089ba34 x23: ffff0e0e40310b00 x22: ffff80008112bb50 x21: ffffaf7b8f246970 x20: ffffaf7b8f773f08 x19: ffff0e0e4089b800 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 000000002de4aa60 x14: 0000000000000000 x13: 2de4acf000000000 x12: 0000000000000020 x11: 0000000000000018 x10: 0000000000000020 x9 : ffffaf7b90601000 x8 : ffff0e0e48739140 x7 : 0000000000000000 x6 : 000000000000003f x5 : ffff0e0e40310b28 x4 : 0000000000000000 x3 : ffff0e0e40310720 x2 : ffff0e0e40310728 x1 : 0000000000000000 x0 : ffff0e0e40310710 Call trace: binder_inc_ref_for_node+0x500/0x544 binder_transaction+0xf68/0x2620 binder_thread_write+0x5bc/0x139c binder_ioctl+0xef4/0x10c8 [...] This patch adds back the previous behavior of assigning the next non-zero descriptor if references to previous context managers still exist. It amends both strategies, the newer dbitmap code and also the legacy slow_desc_lookup_olocked(), by allowing them to start looking for available descriptors at a given offset. Fixes: 15d9da3f81 ("binder: use bitmap for faster descriptor lookup") Cc: stable@vger.kernel.org Reported-and-tested-by: syzbot+3dae065ca76952a67257@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/000000000000c1c0a0061d1e6979@google.com/ Reviewed-by: Alice Ryhl <aliceryhl@google.com> Signed-off-by: Carlos Llamas <cmllamas@google.com> Link: https://lore.kernel.org/r/20240722150512.4192473-1-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2024-07-31 13:47:48 +02:00
..
binder_alloc_selftest.c	android: binder: fix a kernel-doc enum warning	2023-12-06 08:48:26 +09:00
binder_alloc.c	binder_alloc: Replace kcalloc with kvcalloc to mitigate OOM issues	2024-07-03 16:22:36 +02:00
binder_alloc.h	binder: switch alloc->mutex to spinlock_t	2023-12-05 09:23:41 +09:00
binder_internal.h	binder: use bitmap for faster descriptor lookup	2024-07-03 16:21:59 +02:00
binder_trace.h	binder: keep vma addresses type as unsigned long	2023-12-05 09:23:38 +09:00
binder.c	binder: fix descriptor lookup for context manager	2024-07-31 13:47:48 +02:00
binderfs.c	android: removed duplicate linux/errno	2024-01-07 09:48:26 +01:00
dbitmap.h	binder: fix descriptor lookup for context manager	2024-07-31 13:47:48 +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