CVE: CVE-2024-26656
Published: 2024-04-02
Description: In the Linux kernel, the following vulnerability has been resolved:

drm/amdgpu: fix use-after-free bug

The bug can be triggered by sending a single amdgpu_gem_userptr_ioctl
to the AMDGPU DRM driver on any ASICs with an invalid address and size.
The bug was reported by Joonkyo Jung <joonkyoj@yonsei.ac.kr>.
For example the following code:

static void Syzkaller1(int fd)
{
	struct drm_amdgpu_gem_userptr arg;
	int ret;

	arg.addr = 0xffffffffffff0000;
	arg.size = 0x80000000; /*2 Gb*/
	arg.flags = 0x7;
	ret = drmIoctl(fd, 0xc1186451/*amdgpu_gem_userptr_ioctl*/, &arg);
}

Due to the address and size are not valid there is a failure in
amdgpu_hmm_register->mmu_interval_notifier_insert->__mmu_interval_notifier_insert->
check_shl_overflow, but we even the amdgpu_hmm_register failure we still call
amdgpu_hmm_unregister into  amdgpu_gem_object_free which causes access to a bad address.
The following stack is below when the issue is reproduced when Kazan is enabled:

[  +0.000014] Hardware name: ASUS System Product Name/ROG STRIX B550-F GAMING (WI-FI), BIOS 1401 12/03/2020
[  +0.000009] RIP: 0010:mmu_interval_notifier_remove+0x327/0x340
[  +0.000017] Code: ff ff 49 89 44 24 08 48 b8 00 01 00 00 00 00 ad de 4c 89 f7 49 89 47 40 48 83 c0 22 49 89 47 48 e8 ce d1 2d 01 e9 32 ff ff ff <0f> 0b e9 16 ff ff ff 4c 89 ef e8 fa 14 b3 ff e9 36 ff ff ff e8 80
[  +0.000014] RSP: 0018:ffffc[PII_REDACTED]8 EFLAGS: 00010246
[  +0.000013] RAX: [PII_REDACTED] RBX: 1ffff920004caf35 RCX: ffffffff8160565b
[  +0.000011] RDX: dffffc[PII_REDACTED] RSI: [PII_REDACTED] RDI: ffff8881a9f78260
[  +0.000010] RBP: ffffc90002657a70 R08: [PII_REDACTED] R09: fffff520004caf25
[  +0.000010] R10: [PII_REDACTED] R11: ffffffff8161d1d6 R12: ffff88810e988c00
[  +0.000010] R13: ffff888126fb5a00 R14: ffff88810e988c0c R15: ffff8881a9f78260
[  +0.000011] FS:  00007ff9ec848540(0000) GS:ffff8883cc880000(0000) knlGS:[PII_REDACTED]
[  +0.000012] CS:  0010 DS: 0000 ES: 0000 CR0: [PII_REDACTED]
[  +0.000010] CR2: 000055b3f7e14328 CR3: 00000001b5770000 CR4:[PII_REDACTED]350ef0
[  +0.000010] Call Trace:
[  +0.000006]  <TASK>
[  +0.000007]  ? show_regs+0x6a/0x80
[  +0.000018]  ? __warn+0xa5/0x1b0
[  +0.000019]  ? mmu_interval_notifier_remove+0x327/0x340
[  +0.000018]  ? report_bug+0x24a/0x290
[  +0.000022]  ? handle_bug+0x46/0x90
[  +0.000015]  ? exc_invalid_op+0x19/0x50
[  +0.000016]  ? asm_exc_invalid_op+0x1b/0x20
[  +0.000017]  ? kasan_save_stack+0x26/0x50
[  +0.000017]  ? mmu_interval_notifier_remove+0x23b/0x340
[  +0.000019]  ? mmu_interval_notifier_remove+0x327/0x340
[  +0.000019]  ? mmu_interval_notifier_remove+0x23b/0x340
[  +0.000020]  ? __pfx_mmu_interval_notifier_remove+0x10/0x10
[  +0.000017]  ? kasan_save_alloc_info+0x1e/0x30
[  +0.000018]  ? srso_return_thunk+0x5/0x5f
[  +0.000014]  ? __kasan_kmalloc+0xb1/0xc0
[  +0.000018]  ? srso_return_thunk+0x5/0x5f
[  +0.000013]  ? __kasan_check_read+0x11/0x20
[  +0.000020]  amdgpu_hmm_unregister+0x34/0x50 [amdgpu]
[  +0.004695]  amdgpu_gem_object_free+0x66/0xa0 [amdgpu]
[  +0.004534]  ? __pfx_amdgpu_gem_object_free+0x10/0x10 [amdgpu]
[  +0.004291]  ? do_syscall_64+0x5f/0xe0
[  +0.000023]  ? srso_return_thunk+0x5/0x5f
[  +0.000017]  drm_gem_object_free+0x3b/0x50 [drm]
[  +0.000489]  amdgpu_gem_userptr_ioctl+0x306/0x500 [amdgpu]
[  +0.004295]  ? __pfx_amdgpu_gem_userptr_ioctl+0x10/0x10 [amdgpu]
[  +0.004270]  ? srso_return_thunk+0x5/0x5f
[  +0.000014]  ? __this_cpu_preempt_check+0x13/0x20
[  +0.000015]  ? srso_return_thunk+0x5/0x5f
[  +0.000013]  ? sysvec_apic_timer_interrupt+0x57/0xc0
[  +0.000020]  ? srso_return_thunk+0x5/0x5f
[  +0.000014]  ? asm_sysvec_apic_timer_interrupt+0x1b/0x20
[  +0.000022]  ? drm_ioctl_kernel+0x17b/0x1f0 [drm]
[  +0.000496]  ? __pfx_amdgpu_gem_userptr_ioctl+0x10/0x10 [amdgpu]
[  +0.004272]  ? drm_ioctl_kernel+0x190/0x1f0 [drm]
[  +0.000492]  drm_ioctl_kernel+0x140/0x1f0 [drm]
[  +0.000497]  ? __pfx_amdgpu_gem_userptr_ioctl+0x10/0x10 [amdgpu]
[  +0.004297]  ? __pfx_drm_ioctl_kernel+0x10/0x10 [d
---truncated---
CVSS Score: 5.5 (MEDIUM)
CWE: CWE-416
References: https://git.kernel.org/stable/c/22207fd5c80177b860279653d017474b2812af5e; https://git.kernel.org/stable/c/22f665ecfd1225afa1309ace623157d12bb9bb0c; https://git.kernel.org/stable/c/2e13f88e01ae7e28a7e831bf5c2409c4748e0a60