Minimal supplement to upstream Kernel Self Protection Project changes. Features already provided by SELinux + Yama and archs other than multiarch arm64 / x86_64 aren't in scope. Only tags have stable history. Shared IRC channel with KSPP: irc.libera.chat #linux-hardening
a0ffc51e20
The last part of drm_atomic_check_only is testing whether we need to
fail with -EINVAL when modeset is not allowed, but forgets to return
the value when atomic_check() fails first.
This results in -EDEADLK being replaced by -EINVAL, and the sanity
check in drm_modeset_drop_locks kicks in:
[ 308.531734] ------------[ cut here ]------------
[ 308.531791] WARNING: CPU: 0 PID: 1886 at drivers/gpu/drm/drm_modeset_lock.c:217 drm_modeset_drop_locks+0x33/0xc0 [drm]
[ 308.531828] Modules linked in:
[ 308.532050] CPU: 0 PID: 1886 Comm: kms_atomic Tainted: G U W 4.13.0-rc5-patser+ #5225
[ 308.532082] Hardware name: NUC5i7RYB, BIOS RYBDWi35.86A.0246.2015.0309.1355 03/09/2015
[ 308.532124] task: ffff8800cd9dae00 task.stack: ffff8800ca3b8000
[ 308.532168] RIP: 0010:drm_modeset_drop_locks+0x33/0xc0 [drm]
[ 308.532189] RSP: 0018:ffff8800ca3bf980 EFLAGS: 00010282
[ 308.532211] RAX: dffffc0000000000 RBX: ffff8800ca3bfaf8 RCX: 0000000013a171e6
[ 308.532235] RDX: 1ffff10019477f69 RSI: ffffffffa8ba4fa0 RDI: ffff8800ca3bfb48
[ 308.532258] RBP: ffff8800ca3bf998 R08: 0000000000000000 R09: 0000000000000003
[ 308.532281] R10: 0000000079dbe066 R11: 00000000f760b34b R12: 0000000000000001
[ 308.532304] R13: dffffc0000000000 R14: 00000000ffffffea R15: ffff880096889680
[ 308.532328] FS: 00007ff00959cec0(0000) GS:ffff8800d4e00000(0000) knlGS:0000000000000000
[ 308.532359] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 308.532380] CR2: 0000000000000008 CR3: 00000000ca2e3000 CR4: 00000000003406f0
[ 308.532402] Call Trace:
[ 308.532440] drm_mode_atomic_ioctl+0x19fa/0x1c00 [drm]
[ 308.532488] ? drm_atomic_set_property+0x1220/0x1220 [drm]
[ 308.532565] ? avc_has_extended_perms+0xc39/0xff0
[ 308.532593] ? lock_downgrade+0x610/0x610
[ 308.532640] ? drm_atomic_set_property+0x1220/0x1220 [drm]
[ 308.532680] drm_ioctl_kernel+0x154/0x1a0 [drm]
[ 308.532755] drm_ioctl+0x624/0x8f0 [drm]
[ 308.532858] ? drm_atomic_set_property+0x1220/0x1220 [drm]
[ 308.532976] ? drm_getunique+0x210/0x210 [drm]
[ 308.533061] do_vfs_ioctl+0xd92/0xe40
[ 308.533121] ? ioctl_preallocate+0x1b0/0x1b0
[ 308.533160] ? selinux_capable+0x20/0x20
[ 308.533191] ? do_fcntl+0x1b1/0xbf0
[ 308.533219] ? kasan_slab_free+0xa2/0xb0
[ 308.533249] ? f_getown+0x4b/0xa0
[ 308.533278] ? putname+0xcf/0xe0
[ 308.533309] ? security_file_ioctl+0x57/0x90
[ 308.533342] SyS_ioctl+0x4e/0x80
[ 308.533374] entry_SYSCALL_64_fastpath+0x18/0xad
[ 308.533405] RIP: 0033:0x7ff00779e4d7
[ 308.533431] RSP: 002b:00007fff66a043d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[ 308.533481] RAX: ffffffffffffffda RBX: 000000e7c7ca5910 RCX: 00007ff00779e4d7
[ 308.533560] RDX: 00007fff66a04430 RSI: 00000000c03864bc RDI: 0000000000000003
[ 308.533608] RBP: 00007ff007a5fb00 R08: 000000e7c7ca4620 R09: 000000e7c7ca5e60
[ 308.533647] R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000070
[ 308.533685] R13: 0000000000000000 R14: 0000000000000000 R15: 000000e7c7ca5930
[ 308.533770] Code: ff df 55 48 89 e5 41 55 41 54 53 48 89 fb 48 83 c7
50 48 89 fa 48 c1 ea 03 80 3c 02 00 74 05 e8 94 d4 16 e7 48 83 7b 50 00
74 02 <0f> ff 4c 8d 6b 58 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1
[ 308.534086] ---[ end trace 77f11e53b1df44ad ]---
Solve this by adding the missing return.
This is also a bugfix because we could end up rejecting updates with
-EINVAL because of a early -EDEADLK, while if atomic_check ran to
completion it might have downgraded the modeset to a fastset.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Testcase: kms_atomic
Link: https://patchwork.freedesktop.org/patch/msgid/20170815095706.23624-1-maarten.lankhorst@linux.intel.com
Fixes:
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.