CVE-2026-43368

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

drm/i915: Fix potential overflow of shmem scatterlist length

When a scatterlists table of a GEM shmem object of size 4 GB or more is

populated with pages allocated from a folio, unsigned int .length

attribute of a scatterlist may get overflowed if total byte length of

pages allocated to that single scatterlist happens to reach or cross the

4GB limit. As a consequence, users of the object may suffer from hitting

unexpected, premature end of the object's backing pages.

[278.780187] ------------[ cut here ]------------

[278.780377] WARNING: CPU: 1 PID: 2326 at drivers/gpu/drm/i915/i915_mm.c:55 remap_sg+0x199/0x1d0 [i915]

...

[278.780654] CPU: 1 UID: 0 PID: 2326 Comm: gem_mmap_offset Tainted: G S U 6.17.0-rc1-CI_DRM_16981-ged823aaa0607+ #1 PREEMPT(voluntary)

[278.780656] Tainted: [S]=CPU_OUT_OF_SPEC, [U]=USER

[278.780658] Hardware name: Intel Corporation Meteor Lake Client Platform/MTL-P LP5x T3 RVP, BIOS MTLPFWI1.R00.3471.D91.2401310918 01/31/2024

[278.780659] RIP: 0010:remap_sg+0x199/0x1d0 [i915]

...

[278.780786] Call Trace:

[278.780787] <TASK>

[278.780788] ? __apply_to_page_range+0x3e6/0x910

[278.780795] ? __pfx_remap_sg+0x10/0x10 [i915]

[278.780906] apply_to_page_range+0x14/0x30

[278.780908] remap_io_sg+0x14d/0x260 [i915]

[278.781013] vm_fault_cpu+0xd2/0x330 [i915]

[278.781137] __do_fault+0x3a/0x1b0

[278.781140] do_fault+0x322/0x640

[278.781143] __handle_mm_fault+0x938/0xfd0

[278.781150] handle_mm_fault+0x12c/0x300

[278.781152] ? lock_mm_and_find_vma+0x4b/0x760

[278.781155] do_user_addr_fault+0x2d6/0x8e0

[278.781160] exc_page_fault+0x96/0x2c0

[278.781165] asm_exc_page_fault+0x27/0x30

...

That issue was apprehended by the author of a change that introduced it,

and potential risk even annotated with a comment, but then never addressed.

When adding folio pages to a scatterlist table, take care of byte length

of any single scatterlist not exceeding max_segment.

(cherry picked from commit 06249b4e691a75694c014a61708c007fb5755f60)