From: David Sterba <dsterba@suse.cz>
To: Johannes Thumshirn <jth@kernel.org>
Cc: linux-btrfs@vger.kernel.org,
Johannes Thumshirn <johannes.thumshirn@wdc.com>,
Filipe Manana <fdmanana@kernel.org>,
syzbot+510a1abbb8116eeb341d@syzkaller.appspotmail.com,
Qu Wenruo <wqu@suse.com>
Subject: Re: [PATCH v2] btrfs: fix information leak in btrfs_ioctl_logical_to_ino()
Date: Wed, 17 Apr 2024 23:19:02 +0200 [thread overview]
Message-ID: <20240417211902.GU3492@twin.jikos.cz> (raw)
In-Reply-To: <7eb2d171cdb1a2a89288a989dc0ef28c21bebc59.1713361686.git.jth@kernel.org>
On Wed, Apr 17, 2024 at 03:48:49PM +0200, Johannes Thumshirn wrote:
> From: Johannes Thumshirn <johannes.thumshirn@wdc.com>
>
> Syzbot reported the following information leak for in
> btrfs_ioctl_logical_to_ino():
>
> BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:114 [inline]
> BUG: KMSAN: kernel-infoleak in _copy_to_user+0xbc/0x110 lib/usercopy.c:40
> instrument_copy_to_user include/linux/instrumented.h:114 [inline]
> _copy_to_user+0xbc/0x110 lib/usercopy.c:40
> copy_to_user include/linux/uaccess.h:191 [inline]
> btrfs_ioctl_logical_to_ino+0x440/0x750 fs/btrfs/ioctl.c:3499
> btrfs_ioctl+0x714/0x1260
> vfs_ioctl fs/ioctl.c:51 [inline]
> __do_sys_ioctl fs/ioctl.c:904 [inline]
> __se_sys_ioctl+0x261/0x450 fs/ioctl.c:890
> __x64_sys_ioctl+0x96/0xe0 fs/ioctl.c:890
> x64_sys_call+0x1883/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:17
> do_syscall_x64 arch/x86/entry/common.c:52 [inline]
> do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> Uninit was created at:
> __kmalloc_large_node+0x231/0x370 mm/slub.c:3921
> __do_kmalloc_node mm/slub.c:3954 [inline]
> __kmalloc_node+0xb07/0x1060 mm/slub.c:3973
> kmalloc_node include/linux/slab.h:648 [inline]
> kvmalloc_node+0xc0/0x2d0 mm/util.c:634
> kvmalloc include/linux/slab.h:766 [inline]
> init_data_container+0x49/0x1e0 fs/btrfs/backref.c:2779
> btrfs_ioctl_logical_to_ino+0x17c/0x750 fs/btrfs/ioctl.c:3480
> btrfs_ioctl+0x714/0x1260
> vfs_ioctl fs/ioctl.c:51 [inline]
> __do_sys_ioctl fs/ioctl.c:904 [inline]
> __se_sys_ioctl+0x261/0x450 fs/ioctl.c:890
> __x64_sys_ioctl+0x96/0xe0 fs/ioctl.c:890
> x64_sys_call+0x1883/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:17
> do_syscall_x64 arch/x86/entry/common.c:52 [inline]
> do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> Bytes 40-65535 of 65536 are uninitialized
> Memory access of size 65536 starts at ffff888045a40000
>
> This happens, because we're copying a 'struct btrfs_data_container' back
> to user-space. This btrfs_data_container is allocated in
> 'init_data_container()' via kvmalloc(), which does not zero-fill the
> memory.
>
> Fix this by using kvzalloc() which zeroes out the memory on allocation.
>
> Reported-by: <syzbot+510a1abbb8116eeb341d@syzkaller.appspotmail.com>
> Signed-off-by: Johannes Thumshirn <Johannes.thumshirn@wdc.com>
> Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
prev parent reply other threads:[~2024-04-17 21:26 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-17 13:48 [PATCH v2] btrfs: fix information leak in btrfs_ioctl_logical_to_ino() Johannes Thumshirn
2024-04-17 13:49 ` Filipe Manana
2024-04-17 21:19 ` David Sterba [this message]
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