Radeon R100 UBSAN warning

[Alex Deucher]

On Mon, May 16, 2016 at 9:16 AM, Meelis Roos <mroos at linux.ee> wrote:
> I am seeing the following UBSAN warning on three of my computers (4.6.0
> with UBSAN turned on). I am reporting this because some of the UBSAN
> reports have been correct (some have been false positives though).

Already fixed in drm-next:
https://cgit.freedesktop.org/~airlied/linux/commit/?h=drm-next&id=b2c0cbd657173f024138d6421774007690ceeffd

Alex

>
> [    9.372287] ================================================================================
> [    9.372423] UBSAN: Undefined behaviour in drivers/gpu/drm/radeon/r100.c:595:15
> [    9.372559] shift exponent 255 is too large for 32-bit type 'int'
> [    9.372696] CPU: 0 PID: 222 Comm: systemd-udevd Not tainted 4.6.0 #129
> [    9.372831] Hardware name: MicroLink                               /D850MV                         , BIOS MV85010A.86A.0067.P24.0304081124 04/08/2003
> [    9.373058]  00000000 c12244c8 f8df9704 c1224aa4 f8df96d4 00000001 00000202 00353532
> [    9.373516]  00000236 00000246 00000246 00000006 00000000 00010246 0000001c 00000006
> [    9.373972]  c17f6842 00000031 c1074ab1 00000000 00000000 00000246 00000002 f4a06800
> [    9.374427] Call Trace:
> [    9.374567]  [<c12244c8>] ? ubsan_epilogue+0x8/0x23
> [    9.374704]  [<c1224aa4>] ? __ubsan_handle_shift_out_of_bounds+0xd5/0xdd
> [    9.374843]  [<c1074ab1>] ? vprintk_emit+0x37a/0x390
> [    9.375156]  [<f8ce6bac>] ? r100_hpd_init+0x72/0xb7 [radeon]
> [    9.375437]  [<f8cdb105>] ? radeon_modeset_init+0x753/0xe7b [radeon]
> [    9.375719]  [<f8cb044e>] ? radeon_driver_load_kms+0xd8/0x196 [radeon]
> [    9.375884]  [<f8891eee>] ? drm_dev_register+0x75/0xad [drm]
> [    9.376041]  [<f88948f1>] ? drm_get_pci_dev+0x11d/0x23e [drm]
> [    9.376135]  [<c12306b2>] ? pci_device_probe+0x9f/0xee
> [    9.376135]  [<c12bfb7c>] ? driver_probe_device+0x149/0x271
> [    9.376135]  [<c12bfd2a>] ? __driver_attach+0x86/0xa1
> [    9.376135]  [<c12bdea0>] ? bus_for_each_dev+0x47/0x5a
> [    9.376135]  [<c12bf3f7>] ? driver_attach+0x24/0x27
> [    9.376135]  [<c12bfca4>] ? driver_probe_device+0x271/0x271
> [    9.376135]  [<c12bf111>] ? bus_add_driver+0xed/0x1db
> [    9.376135]  [<f8e58000>] ? 0xf8e58000
> [    9.376135]  [<c12c0603>] ? driver_register+0x9a/0xcb
> [    9.376135]  [<c10004c1>] ? do_one_initcall+0x159/0x1d9
> [    9.376135]  [<c10b25d4>] ? __free_one_page+0x1a1/0x369
> [    9.376135]  [<c10e4e66>] ? kernel_poison_pages+0x10/0xc4
> [    9.376135]  [<c10b1e8e>] ? free_pages_prepare+0x1f7/0x21c
> [    9.376135]  [<c10e82e2>] ? kmem_cache_alloc+0xa2/0xd6
> [    9.376135]  [<c10abbe7>] ? do_init_module+0x17/0x21a
> [    9.376135]  [<c10abc46>] ? do_init_module+0x76/0x21a
> [    9.376135]  [<c109768a>] ? load_module+0x1b28/0x206a
> [    9.376135]  [<c1097ced>] ? SyS_finit_module+0x71/0x79
> [    9.376135]  [<c100169f>] ? do_fast_syscall_32+0xd9/0x111
> [    9.376135]  [<c13ebad7>] ? sysenter_past_esp+0x40/0x6a
> [    9.376135] ================================================================================
>
> --
> Meelis Roos (mroos at linux.ee)
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