Subject: CVE-2022-48662: drm/i915/gem: Really move i915_gem_context.link under ref protection

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

drm/i915/gem: Really move i915_gem_context.link under ref protection

i915_perf assumes that it can use the i915_gem_context reference to
protect its i915->gem.contexts.list iteration. However, this requires
that we do not remove the context from the list until after we drop the
final reference and release the struct. If, as currently, we remove the
context from the list during context_close(), the link.next pointer may
be poisoned while we are holding the context reference and cause a GPF:

[ 4070.573157] i915 0000:00:02.0: [drm:i915_perf_open_ioctl [i915]] filtering on ctx_id=0x1fffff ctx_id_mask=0x1fffff
[ 4070.574881] general protection fault, probably for non-canonical address 0xdead000000000100: 0000 [#1] PREEMPT SMP
[ 4070.574897] CPU: 1 PID: 284392 Comm: amd_performance Tainted: G            E     5.17.9 #180
[ 4070.574903] Hardware name: Intel Corporation NUC7i5BNK/NUC7i5BNB, BIOS BNKBL357.86A.0052.2017.0918.1346 09/18/2017
[ 4070.574907] RIP: 0010:oa_configure_all_contexts.isra.0+0x222/0x350 [i915]
[ 4070.574982] Code: 08 e8 32 6e 10 e1 4d 8b 6d 50 b8 ff ff ff ff 49 83 ed 50 f0 41 0f c1 04 24 83 f8 01 0f 84 e3 00 00 00 85 c0 0f 8e fa 00 00 00 <49> 8b 45 50 48 8d 70 b0 49 8d 45 50 48 39 44 24 10 0f 85 34 fe ff
[ 4070.574990] RSP: 0018:ffffc90002077b78 EFLAGS: 00010202
[ 4070.574995] RAX: 0000000000000002 RBX: 0000000000000002 RCX: 0000000000000000
[ 4070.575000] RDX: 0000000000000001 RSI: ffffc90002077b20 RDI: ffff88810ddc7c68
[ 4070.575004] RBP: 0000000000000001 R08: ffff888103242648 R09: fffffffffffffffc
[ 4070.575008] R10: ffffffff82c50bc0 R11: 0000000000025c80 R12: ffff888101bf1860
[ 4070.575012] R13: dead0000000000b0 R14: ffffc90002077c04 R15: ffff88810be5cabc
[ 4070.575016] FS:  00007f1ed50c0780(0000) GS:ffff88885ec80000(0000) knlGS:0000000000000000
[ 4070.575021] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 4070.575025] CR2: 00007f1ed5590280 CR3: 000000010ef6f005 CR4: 00000000003706e0
[ 4070.575029] Call Trace:
[ 4070.575033]  <TASK>
[ 4070.575037]  lrc_configure_all_contexts+0x13e/0x150 [i915]
[ 4070.575103]  gen8_enable_metric_set+0x4d/0x90 [i915]
[ 4070.575164]  i915_perf_open_ioctl+0xbc0/0x1500 [i915]
[ 4070.575224]  ? asm_common_interrupt+0x1e/0x40
[ 4070.575232]  ? i915_oa_init_reg_state+0x110/0x110 [i915]
[ 4070.575290]  drm_ioctl_kernel+0x85/0x110
[ 4070.575296]  ? update_load_avg+0x5f/0x5e0
[ 4070.575302]  drm_ioctl+0x1d3/0x370
[ 4070.575307]  ? i915_oa_init_reg_state+0x110/0x110 [i915]
[ 4070.575382]  ? gen8_gt_irq_handler+0x46/0x130 [i915]
[ 4070.575445]  __x64_sys_ioctl+0x3c4/0x8d0
[ 4070.575451]  ? __do_softirq+0xaa/0x1d2
[ 4070.575456]  do_syscall_64+0x35/0x80
[ 4070.575461]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 4070.575467] RIP: 0033:0x7f1ed5c10397
[ 4070.575471] Code: 3c 1c e8 1c ff ff ff 85 c0 79 87 49 c7 c4 ff ff ff ff 5b 5d 4c 89 e0 41 5c c3 66 0f 1f 84 00 00 00 00 00 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d a9 da 0d 00 f7 d8 64 89 01 48
[ 4070.575478] RSP: 002b:00007ffd65c8d7a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[ 4070.575484] RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 00007f1ed5c10397
[ 4070.575488] RDX: 00007ffd65c8d7c0 RSI: 0000000040106476 RDI: 0000000000000006
[ 4070.575492] RBP: 00005620972f9c60 R08: 000000000000000a R09: 0000000000000005
[ 4070.575496] R10: 000000000000000d R11: 0000000000000246 R12: 000000000000000a
[ 4070.575500] R13: 000000000000000d R14: 0000000000000000 R15: 00007ffd65c8d7c0
[ 4070.575505]  </TASK>
[ 4070.575507] Modules linked in: nls_ascii(E) nls_cp437(E) vfat(E) fat(E) i915(E) x86_pkg_temp_thermal(E) intel_powerclamp(E) crct10dif_pclmul(E) crc32_pclmul(E) crc32c_intel(E) aesni_intel(E) crypto_simd(E) intel_gtt(E) cryptd(E) ttm(E) rapl(E) intel_cstate(E) drm_kms_helper(E) cfbfillrect(E) syscopyarea(E) cfbimgblt(E) intel_uncore(E) sysfillrect(E) mei_me(E) sysimgblt(E) i2c_i801(E) fb_sys_fops(E) mei(E) intel_pch_thermal(E) i2c_smbus(E) cfbcopyarea(E) video(E) button(E) efivarfs(E) autofs4(E)
[ 4070.575549] ---[ end trace 0000000000000000 ]---

v3: fix incorrect syntax of spin_lock() replacing spin_lock_irqsave()

v2: irqsave not required in a worker, neither conversion to irq safe
    elsewhere (Tvrtko),
  - perf: it's safe to call gen8_configure_context() even if context has
    been closed, no need to check,
  - drop unrelated cleanup (Andi, Tvrtko)

References: a4e7ccdac38e ("drm/i915: Move context management under GEM")
(cherry picked from commit ad3aa7c31efa5a09b0dba42e66cfdf77e0db7dc2)

The Linux kernel CVE team has assigned CVE-2022-48662 to this issue.

Affected and fixed versions
===========================

	Issue introduced in 5.12 with commit f8246cf4d9a9 and fixed in 5.15.72 with commit 713fa3e4591f
	Issue introduced in 5.12 with commit f8246cf4d9a9 and fixed in 5.19.12 with commit f799e0568d6c
	Issue introduced in 5.12 with commit f8246cf4d9a9 and fixed in 6.0 with commit d119888b09bd

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2022-48662
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	drivers/gpu/drm/i915/gem/i915_gem_context.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/713fa3e4591f65f804bdc88e8648e219fabc9ee1
	https://git.kernel.org/stable/c/f799e0568d6c153368b177e0bbbde7dcc4ce7f1d
	https://git.kernel.org/stable/c/d119888b09bd567e07c6b93a07f175df88857e02