Subject: CVE-2023-52817: drm/amdgpu: Fix a null pointer access when the smc_rreg pointer is NULL

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

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

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

drm/amdgpu: Fix a null pointer access when the smc_rreg pointer is NULL

In certain types of chips, such as VEGA20, reading the amdgpu_regs_smc file could result in an abnormal null pointer access when the smc_rreg pointer is NULL. Below are the steps to reproduce this issue and the corresponding exception log:

1. Navigate to the directory: /sys/kernel/debug/dri/0
2. Execute command: cat amdgpu_regs_smc
3. Exception Log::
[4005007.702554] BUG: kernel NULL pointer dereference, address: 0000000000000000
[4005007.702562] #PF: supervisor instruction fetch in kernel mode
[4005007.702567] #PF: error_code(0x0010) - not-present page
[4005007.702570] PGD 0 P4D 0
[4005007.702576] Oops: 0010 [#1] SMP NOPTI
[4005007.702581] CPU: 4 PID: 62563 Comm: cat Tainted: G           OE     5.15.0-43-generic #46-Ubunt       u
[4005007.702590] RIP: 0010:0x0
[4005007.702598] Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
[4005007.702600] RSP: 0018:ffffa82b46d27da0 EFLAGS: 00010206
[4005007.702605] RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffa82b46d27e68
[4005007.702609] RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff9940656e0000
[4005007.702612] RBP: ffffa82b46d27dd8 R08: 0000000000000000 R09: ffff994060c07980
[4005007.702615] R10: 0000000000020000 R11: 0000000000000000 R12: 00007f5e06753000
[4005007.702618] R13: ffff9940656e0000 R14: ffffa82b46d27e68 R15: 00007f5e06753000
[4005007.702622] FS:  00007f5e0755b740(0000) GS:ffff99479d300000(0000) knlGS:0000000000000000
[4005007.702626] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[4005007.702629] CR2: ffffffffffffffd6 CR3: 00000003253fc000 CR4: 00000000003506e0
[4005007.702633] Call Trace:
[4005007.702636]  <TASK>
[4005007.702640]  amdgpu_debugfs_regs_smc_read+0xb0/0x120 [amdgpu]
[4005007.703002]  full_proxy_read+0x5c/0x80
[4005007.703011]  vfs_read+0x9f/0x1a0
[4005007.703019]  ksys_read+0x67/0xe0
[4005007.703023]  __x64_sys_read+0x19/0x20
[4005007.703028]  do_syscall_64+0x5c/0xc0
[4005007.703034]  ? do_user_addr_fault+0x1e3/0x670
[4005007.703040]  ? exit_to_user_mode_prepare+0x37/0xb0
[4005007.703047]  ? irqentry_exit_to_user_mode+0x9/0x20
[4005007.703052]  ? irqentry_exit+0x19/0x30
[4005007.703057]  ? exc_page_fault+0x89/0x160
[4005007.703062]  ? asm_exc_page_fault+0x8/0x30
[4005007.703068]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[4005007.703075] RIP: 0033:0x7f5e07672992
[4005007.703079] Code: c0 e9 b2 fe ff ff 50 48 8d 3d fa b2 0c 00 e8 c5 1d 02 00 0f 1f 44 00 00 f3 0f        1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 0f 05 <48> 3d 00 f0 ff ff 77 56 c3 0f 1f 44 00 00 48 83 e       c 28 48 89 54 24
[4005007.703083] RSP: 002b:00007ffe03097898 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[4005007.703088] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f5e07672992
[4005007.703091] RDX: 0000000000020000 RSI: 00007f5e06753000 RDI: 0000000000000003
[4005007.703094] RBP: 00007f5e06753000 R08: 00007f5e06752010 R09: 00007f5e06752010
[4005007.703096] R10: 0000000000000022 R11: 0000000000000246 R12: 0000000000022000
[4005007.703099] R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
[4005007.703105]  </TASK>
[4005007.703107] Modules linked in: nf_tables libcrc32c nfnetlink algif_hash af_alg binfmt_misc nls_       iso8859_1 ipmi_ssif ast intel_rapl_msr intel_rapl_common drm_vram_helper drm_ttm_helper amd64_edac t       tm edac_mce_amd kvm_amd ccp mac_hid k10temp kvm acpi_ipmi ipmi_si rapl sch_fq_codel ipmi_devintf ipm       i_msghandler msr parport_pc ppdev lp parport mtd pstore_blk efi_pstore ramoops pstore_zone reed_solo       mon ip_tables x_tables autofs4 ib_uverbs ib_core amdgpu(OE) amddrm_ttm_helper(OE) amdttm(OE) iommu_v       2 amd_sched(OE) amdkcl(OE) drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops cec rc_core        drm igb ahci xhci_pci libahci i2c_piix4 i2c_algo_bit xhci_pci_renesas dca
[4005007.703184] CR2: 0000000000000000
[4005007.703188] ---[ end trace ac65a538d240da39 ]---
[4005007.800865] RIP: 0010:0x0
[4005007.800871] Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
[4005007.800874] RSP: 0018:ffffa82b46d27da0 EFLAGS: 00010206
[4005007.800878] RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffa82b46d27e68
[4005007.800881] RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff9940656e0000
[4005007.800883] RBP: ffffa82b46d27dd8 R08: 0000000000000000 R09: ffff994060c07980
[4005007.800886] R10: 0000000000020000 R11: 0000000000000000 R12: 00007f5e06753000
[4005007.800888] R13: ffff9940656e0000 R14: ffffa82b46d27e68 R15: 00007f5e06753000
[4005007.800891] FS:  00007f5e0755b740(0000) GS:ffff99479d300000(0000) knlGS:0000000000000000
[4005007.800895] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[4005007.800898] CR2: ffffffffffffffd6 CR3: 00000003253fc000 CR4: 00000000003506e0

The Linux kernel CVE team has assigned CVE-2023-52817 to this issue.

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

	Fixed in 4.19.300 with commit bf2d51eedf03
	Fixed in 5.4.262 with commit 437e0fa907ba
	Fixed in 5.10.202 with commit f475d5502f33
	Fixed in 5.15.140 with commit 174f62a0aa15
	Fixed in 6.1.64 with commit 6c1b3d89a2dd
	Fixed in 6.5.13 with commit 820daf9ffe2b
	Fixed in 6.6.3 with commit ba3c0796d292
	Fixed in 6.7 with commit 5104fdf50d32

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-2023-52817
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/amd/amdgpu/amdgpu_debugfs.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/bf2d51eedf03bd61e3556e35d74d49e2e6112398
	https://git.kernel.org/stable/c/437e0fa907ba39b4d7eda863c03ea9cf48bd93a9
	https://git.kernel.org/stable/c/f475d5502f33a6c5b149b0afe96316ad1962a64a
	https://git.kernel.org/stable/c/174f62a0aa15c211e60208b41ee9e7cdfb73d455
	https://git.kernel.org/stable/c/6c1b3d89a2dda79881726bb6e37af19c0936d736
	https://git.kernel.org/stable/c/820daf9ffe2b0afb804567b10983fb38bc5ae288
	https://git.kernel.org/stable/c/ba3c0796d292de84f2932cc5bbb0f771fc720996
	https://git.kernel.org/stable/c/5104fdf50d326db2c1a994f8b35dcd46e63ae4ad