From: Alice Ryhl <aliceryhl@google.com>
To: Dan Carpenter <dan.carpenter@linaro.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Carlos Llamas <cmllamas@google.com>
Cc: oe-kbuild@lists.linux.dev, lkp@intel.com,
oe-kbuild-all@lists.linux.dev, linux-kernel@vger.kernel.org,
Wedson Almeida Filho <wedsonaf@gmail.com>,
Matt Gilbride <mattgilbride@google.com>
Subject: Re: drivers/android/binder/rust_binderfs.c:134 binderfs_binder_device_create() error: Calling ida_alloc_max() with a 'max' argument which is a power of 2. -1 missing?
Date: Thu, 18 Dec 2025 08:10:57 +0000 [thread overview]
Message-ID: <aUO3ES90gStGvjxn@google.com> (raw)
In-Reply-To: <202512181203.IOv6IChH-lkp@intel.com>
On Thu, Dec 18, 2025 at 10:17:52AM +0300, Dan Carpenter wrote:
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: ea1013c1539270e372fc99854bc6e4d94eaeff66
> commit: eafedbc7c050c44744fbdf80bdf3315e860b7513 rust_binder: add Rust Binder driver
> config: loongarch-randconfig-r071-20251218 (https://download.01.org/0day-ci/archive/20251218/202512181203.IOv6IChH-lkp@intel.com/config)
> compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 1335a05ab8bc8339ce24be3a9da89d8c3f4e0571)
> rustc: rustc 1.88.0 (6b00bc388 2025-06-23)
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
> | Closes: https://lore.kernel.org/r/202512181203.IOv6IChH-lkp@intel.com/
>
> smatch warnings:
> drivers/android/binder/rust_binderfs.c:134 binderfs_binder_device_create() error: Calling ida_alloc_max() with a 'max' argument which is a power of 2. -1 missing?
> drivers/android/binder/rust_binderfs.c:418 binderfs_binder_ctl_create() error: Calling ida_alloc_max() with a 'max' argument which is a power of 2. -1 missing?
>
> vim +/max +134 drivers/android/binder/rust_binderfs.c
>
> eafedbc7c050c4 Alice Ryhl 2025-09-19 130
> eafedbc7c050c4 Alice Ryhl 2025-09-19 131 /* Reserve new minor number for the new device. */
> eafedbc7c050c4 Alice Ryhl 2025-09-19 132 mutex_lock(&binderfs_minors_mutex);
> eafedbc7c050c4 Alice Ryhl 2025-09-19 133 if (++info->device_count <= info->mount_opts.max)
> eafedbc7c050c4 Alice Ryhl 2025-09-19 @134 minor = ida_alloc_max(&binderfs_minors,
> eafedbc7c050c4 Alice Ryhl 2025-09-19 135 use_reserve ? BINDERFS_MAX_MINOR :
> eafedbc7c050c4 Alice Ryhl 2025-09-19 136 BINDERFS_MAX_MINOR_CAPPED,
>
> ida_alloc_max() takes the maximum valid id not the count. These should
> be BINDERFS_MAX_MINOR - 1, BINDERFS_MAX_MINOR_CAPPED - 1.
Hmm, this is reported for rust_binderfs.c, but looks like binderfs.c has
the same code. That means the bug has been there for a long time.
Alice
next prev parent reply other threads:[~2025-12-18 8:11 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-18 4:51 drivers/android/binder/rust_binderfs.c:134 binderfs_binder_device_create() error: Calling ida_alloc_max() with a 'max' argument which is a power of 2. -1 missing? kernel test robot
2025-12-18 7:17 ` Dan Carpenter
2025-12-18 8:10 ` Alice Ryhl [this message]
2026-01-27 20:48 ` Carlos Llamas
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