drm/amd/display: fix divide error in DM plane scale calcs

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

drm/amd/display: fix divide error in DM plane scale calcs

dm_get_plane_scale doesn't take into account plane scaled size equal to

zero, leading to a kernel oops due to division by zero. Fix by setting

out-scale size as zero when the dst size is zero, similar to what is

done by drm_calc_scale(). This issue started with the introduction of

cursor ovelay mode that uses this function to assess cursor mode changes

via dm_crtc_get_cursor_mode() before checking plane state.

[Dec17 17:14] Oops: divide error: 0000 [#1] PREEMPT SMP NOPTI

[ +0.000018] CPU: 5 PID: 1660 Comm: surface-DP-1 Not tainted 6.10.0+ #231

[ +0.000007] Hardware name: Valve Jupiter/Jupiter, BIOS F7A0131 01/30/2024

[ +0.000004] RIP: 0010:dm_get_plane_scale+0x3f/0x60 [amdgpu]

[ +0.000553] Code: 44 0f b7 41 3a 44 0f b7 49 3e 83 e0 0f 48 0f a3 c2 73 21 69 41 28 e8 03 00 00 31 d2 41 f7 f1 31 d2 89 06 69 41 2c e8 03 00 00 <41> f7 f0 89 07 e9 d7 d8 7e e9 44 89 c8 45 89 c1 41 89 c0 eb d4 66

[ +0.000005] RSP: 0018:ffffa8df0de6b8a0 EFLAGS: 00010246

[ +0.000006] RAX: 00000000000003e8 RBX: ffff9ac65c1f6e00 RCX: ffff9ac65d055500

[ +0.000003] RDX: 0000000000000000 RSI: ffffa8df0de6b8b0 RDI: ffffa8df0de6b8b4

[ +0.000004] RBP: ffff9ac64e7a5800 R08: 0000000000000000 R09: 0000000000000a00

[ +0.000003] R10: 00000000000000ff R11: 0000000000000054 R12: ffff9ac6d0700010

[ +0.000003] R13: ffff9ac65d054f00 R14: ffff9ac65d055500 R15: ffff9ac64e7a60a0

[ +0.000004] FS: 00007f869ea00640(0000) GS:ffff9ac970080000(0000) knlGS:0000000000000000

[ +0.000004] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

[ +0.000003] CR2: 000055ca701becd0 CR3: 000000010e7f2000 CR4: 0000000000350ef0

[ +0.000004] Call Trace:

[ +0.000007] <TASK>

[ +0.000006] ? __die_body.cold+0x19/0x27

[ +0.000009] ? die+0x2e/0x50

[ +0.000007] ? do_trap+0xca/0x110

[ +0.000007] ? do_error_trap+0x6a/0x90

[ +0.000006] ? dm_get_plane_scale+0x3f/0x60 [amdgpu]

[ +0.000504] ? exc_divide_error+0x38/0x50

[ +0.000005] ? dm_get_plane_scale+0x3f/0x60 [amdgpu]

[ +0.000488] ? asm_exc_divide_error+0x1a/0x20

[ +0.000011] ? dm_get_plane_scale+0x3f/0x60 [amdgpu]

[ +0.000593] dm_crtc_get_cursor_mode+0x33f/0x430 [amdgpu]

[ +0.000562] amdgpu_dm_atomic_check+0x2ef/0x1770 [amdgpu]

[ +0.000501] drm_atomic_check_only+0x5e1/0xa30 [drm]

[ +0.000047] drm_mode_atomic_ioctl+0x832/0xcb0 [drm]

[ +0.000050] ? __pfx_drm_mode_atomic_ioctl+0x10/0x10 [drm]

[ +0.000047] drm_ioctl_kernel+0xb3/0x100 [drm]

[ +0.000062] drm_ioctl+0x27a/0x4f0 [drm]

[ +0.000049] ? __pfx_drm_mode_atomic_ioctl+0x10/0x10 [drm]

[ +0.000055] amdgpu_drm_ioctl+0x4e/0x90 [amdgpu]

[ +0.000360] __x64_sys_ioctl+0x97/0xd0

[ +0.000010] do_syscall_64+0x82/0x190

[ +0.000008] ? __pfx_drm_mode_createblob_ioctl+0x10/0x10 [drm]

[ +0.000044] ? srso_return_thunk+0x5/0x5f

[ +0.000006] ? drm_ioctl_kernel+0xb3/0x100 [drm]

[ +0.000040] ? srso_return_thunk+0x5/0x5f

[ +0.000005] ? __check_object_size+0x50/0x220

[ +0.000007] ? srso_return_thunk+0x5/0x5f

[ +0.000005] ? srso_return_thunk+0x5/0x5f

[ +0.000005] ? drm_ioctl+0x2a4/0x4f0 [drm]

[ +0.000039] ? __pfx_drm_mode_createblob_ioctl+0x10/0x10 [drm]

[ +0.000043] ? srso_return_thunk+0x5/0x5f

[ +0.000005] ? srso_return_thunk+0x5/0x5f

[ +0.000005] ? __pm_runtime_suspend+0x69/0xc0

[ +0.000006] ? srso_return_thunk+0x5/0x5f

[ +0.000005] ? amdgpu_drm_ioctl+0x71/0x90 [amdgpu]

[ +0.000366] ? srso_return_thunk+0x5/0x5f

[ +0.000006] ? syscall_exit_to_user_mode+0x77/0x210

[ +0.000007] ? srso_return_thunk+0x5/0x5f

[ +0.000005] ? do_syscall_64+0x8e/0x190

[ +0.000006] ? srso_return_thunk+0x5/0x5f

[ +0.000006] ? do_syscall_64+0x8e/0x190

[ +0.000006] ? srso_return_thunk+0x5/0x5f

[ +0.000007] entry_SYSCALL_64_after_hwframe+0x76/0x7e

[ +0.000008] RIP: 0033:0x55bb7cd962bc

[ +0.000007] Code: 4c 89 6c 24 18 4c 89 64 24 20 4c 89 74 24 28 0f 57 c0 0f 11 44 24 30 89 c7 48 8d 54 24 08 b8 10 00 00 00 be bc 64

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