Commit ec4ddc90 authored by Carlos Llamas's avatar Carlos Llamas Committed by Greg Kroah-Hartman
Browse files

binderfs: fix ida_alloc_max() upper bound 



The 'max' argument of ida_alloc_max() takes the maximum valid ID and not
the "count". Using an ID of BINDERFS_MAX_MINOR (1 << 20) for dev->minor
would exceed the limits of minor numbers (20-bits). Fix this off-by-one
error by subtracting 1 from the 'max'.

Cc: stable@vger.kernel.org
Fixes: 3ad20fe3 ("binder: implement binderfs")
Signed-off-by: default avatarCarlos Llamas <cmllamas@google.com>
Link: https://patch.msgid.link/20260127235545.2307876-2-cmllamas@google.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d6ba7348

drivers/android/binderfs.c

+4 −4
Original line number Diff line number Diff line
@@ -132,8 +132,8 @@ static int binderfs_binder_device_create(struct inode *ref_inode, 
	mutex_lock(&binderfs_minors_mutex);

	if (++info->device_count <= info->mount_opts.max)

		minor = ida_alloc_max(&binderfs_minors,

				      use_reserve ? BINDERFS_MAX_MINOR :

						    BINDERFS_MAX_MINOR_CAPPED,

				      use_reserve ? BINDERFS_MAX_MINOR - 1 :

						    BINDERFS_MAX_MINOR_CAPPED - 1,

				      GFP_KERNEL);

	else

		minor = -ENOSPC;
@@ -408,8 +408,8 @@ static int binderfs_binder_ctl_create(struct super_block *sb) 
	/* Reserve a new minor number for the new device. */

	mutex_lock(&binderfs_minors_mutex);

	minor = ida_alloc_max(&binderfs_minors,

			      use_reserve ? BINDERFS_MAX_MINOR :

					    BINDERFS_MAX_MINOR_CAPPED,

			      use_reserve ? BINDERFS_MAX_MINOR - 1 :

					    BINDERFS_MAX_MINOR_CAPPED - 1,

			      GFP_KERNEL);

	mutex_unlock(&binderfs_minors_mutex);

	if (minor < 0) {