Linux Kernel up to 6.9-rc1 drm amdgpu_cs_wait_ioctl null pointer dereference

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.9-rc1. It has been rated as critical. This vulnerability affects the function amdgpu_cs_wait_ioctl of the component drm. The manipulation leads to null pointer dereference. This vulnerability is referenced as CVE-2024-26657. No exploit is available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.9-rc1. It has been rated as critical. This issue affects the function amdgpu_cs_wait_ioctl of the component drm. The manipulation with an unknown input leads to a null pointer dereference vulnerability. Using CWE to declare the problem leads to CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. Impacted is availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: drm/sched: fix null-ptr-deref in init entity The bug can be triggered by sending an amdgpu_cs_wait_ioctl to the AMDGPU DRM driver on any ASICs with valid context. The bug was reported by Joonkyo Jung . For example the following code: static void Syzkaller2(int fd) { union drm_amdgpu_ctx arg1; union drm_amdgpu_wait_cs arg2; arg1.in.op = AMDGPU_CTX_OP_ALLOC_CTX; ret = drmIoctl(fd, 0x140106442 /* amdgpu_ctx_ioctl */, &arg1); arg2.in.handle = 0x0; arg2.in.timeout = 0x2000000000000; arg2.in.ip_type = AMD_IP_VPE /* 0x9 */; arg2->in.ip_instance = 0x0; arg2.in.ring = 0x0; arg2.in.ctx_id = arg1.out.alloc.ctx_id; drmIoctl(fd, 0xc0206449 /* AMDGPU_WAIT_CS * /, &arg2); } The ioctl AMDGPU_WAIT_CS without previously submitted job could be assumed that the error should be returned, but the following commit 1decbf6bb0b4dc56c9da6c5e57b994ebfc2be3aa modified the logic and allowed to have sched_rq equal to NULL. As a result when there is no job the ioctl AMDGPU_WAIT_CS returns success. The change fixes null-ptr-deref in init entity and the stack below demonstrates the error condition: [ +0.000007] BUG: kernel NULL pointer dereference, address: 0000000000000028 [ +0.007086] #PF: supervisor read access in kernel mode [ +0.005234] #PF: error_code(0x0000) - not-present page [ +0.005232] PGD 0 P4D 0 [ +0.002501] Oops: 0000 [#1] PREEMPT SMP KASAN NOPTI [ +0.005034] CPU: 10 PID: 9229 Comm: amd_basic Tainted: G B W L 6.7.0+ #4 [ +0.007797] Hardware name: ASUS System Product Name/ROG STRIX B550-F GAMING (WI-FI), BIOS 1401 12/03/2020 [ +0.009798] RIP: 0010:drm_sched_entity_init+0x2d3/0x420 [gpu_sched] [ +0.006426] Code: 80 00 00 00 00 00 00 00 e8 1a 81 82 e0 49 89 9c 24 c0 00 00 00 4c 89 ef e8 4a 80 82 e0 49 8b 5d 00 48 8d 7b 28 e8 3d 80 82 e0 83 7b 28 00 0f 84 28 01 00 00 4d 8d ac 24 98 00 00 00 49 8d 5c [ +0.019094] RSP: 0018:ffffc90014c1fa40 EFLAGS: 00010282 [ +0.005237] RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff8113f3fa [ +0.007326] RDX: fffffbfff0a7889d RSI: 0000000000000008 RDI: ffffffff853c44e0 [ +0.007264] RBP: ffffc90014c1fa80 R08: 0000000000000001 R09: fffffbfff0a7889c [ +0.007266] R10: ffffffff853c44e7 R11: 0000000000000001 R12: ffff8881a719b010 [ +0.007263] R13: ffff88810d412748 R14: 0000000000000002 R15: 0000000000000000 [ +0.007264] FS: 00007ffff7045540(0000) GS:ffff8883cc900000(0000) knlGS:0000000000000000 [ +0.008236] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ +0.005851] CR2: 0000000000000028 CR3: 000000011912e000 CR4: 0000000000350ef0 [ +0.007175] Call Trace: [ +0.002561] [ +0.002141] ? show_regs+0x6a/0x80 [ +0.003473] ? __die+0x25/0x70 [ +0.003124] ? page_fault_oops+0x214/0x720 [ +0.004179] ? preempt_count_sub+0x18/0xc0 [ +0.004093] ? __pfx_page_fault_oops+0x10/0x10 [ +0.004590] ? srso_return_thunk+0x5/0x5f [ +0.004000] ? vprintk_default+0x1d/0x30 [ +0.004063] ? srso_return_thunk+0x5/0x5f [ +0.004087] ? vprintk+0x5c/0x90 [ +0.003296] ? drm_sched_entity_init+0x2d3/0x420 [gpu_sched] [ +0.005807] ? srso_return_thunk+0x5/0x5f [ +0.004090] ? _printk+0xb3/0xe0 [ +0.003293] ? __pfx__printk+0x10/0x10 [ +0.003735] ? asm_sysvec_apic_timer_interrupt+0x1b/0x20 [ +0.005482] ? do_user_addr_fault+0x345/0x770 [ +0.004361] ? exc_page_fault+0x64/0xf0 [ +0.003972] ? asm_exc_page_fault+0x27/0x30 [ +0.004271] ? add_taint+0x2a/0xa0 [ +0.003476] ? drm_sched_entity_init+0x2d3/0x420 [gpu_sched] [ +0.005812] amdgpu_ctx_get_entity+0x3f9/0x770 [amdgpu] [ +0.009530] ? finish_task_switch.isra.0+0x129/0x470 [ +0.005068] ? __pfx_amdgpu_ctx_get_entity+0x10/0x10 [amdgpu] [ +0.010063] ? __kasan_check_write+0x14/0x20 [ +0.004356] ? srso_return_thunk+0x5/0x5f [ +0.004001] ? mutex_unlock+0x81/0xd0 [ +0.003802] ? srso_return_thunk+0x5/0x5f [ +0.004096] amdgpu_cs_wait_ioctl+0xf6/0x270 [amdgpu] [ +0.009355] ? __pfx_ ---truncated---

The advisory is shared at git.kernel.org. The identification of this vulnerability is CVE-2024-26657 since 02/19/2024. The exploitation is known to be difficult. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 250062 (Linux Distros Unpatched Vulnerability : CVE-2024-26657), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.9-rc2 eliminates this vulnerability. Applying the patch f34e8bb7d6c6 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (250062). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.9-rc1

License

• open-source

Website

• Vendor: https://www.kernel.org/

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Entryinfo

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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