| Description: | 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 <48> 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---
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