mainlining shenanigans
2dbd9c27ed
My local syzbot instance hit GPF in ttm_bo_release().
Unfortunately, syzbot didn't produce a reproducer for this, but I
found out possible scenario:
drm_gem_vram_create() <-- drm_gem_vram_object kzalloced
(bo embedded in this object)
ttm_bo_init()
ttm_bo_init_reserved()
ttm_resource_alloc()
man->func->alloc() <-- allocation failure
ttm_bo_put()
ttm_bo_release()
ttm_mem_io_free() <-- bo->resource == NULL passed
as second argument
*GPF*
Added NULL check inside ttm_mem_io_free() to prevent reported GPF and
make this function NULL save in future.
Same problem was in ttm_bo_move_to_lru_tail() as Christian reported.
ttm_bo_move_to_lru_tail() is called in ttm_bo_release() and mem pointer
can be NULL as well as in ttm_mem_io_free().
Fail log:
KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]
...
RIP: 0010:ttm_mem_io_free+0x28/0x170 drivers/gpu/drm/ttm/ttm_bo_util.c:66
..
Call Trace:
ttm_bo_release+0xd94/0x10a0 drivers/gpu/drm/ttm/ttm_bo.c:422
kref_put include/linux/kref.h:65 [inline]
ttm_bo_put drivers/gpu/drm/ttm/ttm_bo.c:470 [inline]
ttm_bo_init_reserved+0x7cb/0x960 drivers/gpu/drm/ttm/ttm_bo.c:1050
ttm_bo_init+0x105/0x270 drivers/gpu/drm/ttm/ttm_bo.c:1074
drm_gem_vram_create+0x332/0x4c0 drivers/gpu/drm/drm_gem_vram_helper.c:228
Fixes:
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.