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eb538b5574
The function xe_vm_prepare_vma was blindly accepting zero as the
number of fences and forwarded that to drm_exec_prepare_obj.
However, that leads to an out-of-bounds shift in the
dma_resv_reserve_fences() and while one could argue that the
dma_resv code should be robust against that, avoid attempting
to reserve zero fences.
Relevant stack trace:
[773.183188] ------------[ cut here ]------------
[773.183199] UBSAN: shift-out-of-bounds in ../include/linux/log2.h:57:13
[773.183241] shift exponent 64 is too large for 64-bit type 'long unsigned int'
[773.183254] CPU: 2 PID: 1816 Comm: xe_evict Tainted: G U 6.8.0-rc3-xe #1
[773.183256] Hardware name: ASUS System Product Name/PRIME Z690-P D4, BIOS 2014 10/14/2022
[773.183257] Call Trace:
[773.183258] <TASK>
[773.183260] dump_stack_lvl+0xaf/0xd0
[773.183266] dump_stack+0x10/0x20
[773.183283] ubsan_epilogue+0x9/0x40
[773.183286] __ubsan_handle_shift_out_of_bounds+0x10f/0x170
[773.183293] dma_resv_reserve_fences.cold+0x2b/0x48
[773.183295] ? ww_mutex_lock+0x3c/0x110
[773.183301] drm_exec_prepare_obj+0x45/0x60 [drm_exec]
[773.183313] xe_vm_prepare_vma+0x33/0x70 [xe]
[773.183375] xe_vma_destroy_unlocked+0x55/0xa0 [xe]
[773.183427] xe_vm_close_and_put+0x526/0x940 [xe]
Fixes: 2714d50936 ("drm/xe: Convert pagefaulting code to use drm_exec")
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240208132115.3132-1-thomas.hellstrom@linux.intel.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.