Affected: Linux

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

drm/i915/reset: Fix error_state_read ptr + offset use

Fix our pointer offset usage in error_state_read when there is no i915_gpu_coredump but buf offset is non-zero.

This fixes a kernel page fault can happen when multiple tests are running concurrently in a loop and one is producing engine resets and consuming the i915 error_state dump while the other is forcing full GT resets. (takes a while to trigger).

The dmesg call trace:

[ 5590.803000] BUG: unable to handle page fault for address: ffffffffa0b0e000 [ 5590.803009] #PF: supervisor read access in kernel mode [ 5590.803013] #PF: error_code(0x0000) - not-present page [ 5590.803016] PGD 5814067 P4D 5814067 PUD 5815063 PMD 109de4067 PTE 0 [ 5590.803022] Oops: 0000 [#1] PREEMPT SMP NOPTI [ 5590.803026] CPU: 5 PID: 13656 Comm: i915_hangman Tainted: G U 5.17.0-rc5-ups69-guc-err-capt-rev6+ #136 [ 5590.803033] Hardware name: Intel Corporation Alder Lake Client Platform/AlderLake-M LP4x RVP, BIOS ADLPFWI1.R00. 3031.A02.2201171222 01/17/2022 [ 5590.803039] RIP: 0010:memcpy_erms+0x6/0x10 [ 5590.803045] Code: fe ff ff cc eb 1e 0f 1f 00 48 89 f8 48 89 d1 48 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 c3 66 0f 1f 44 00 00 48 89 f8 48 89 d1 <f3> a4 c3 0f 1f 80 00 00 00 00 48 89 f8 48 83 fa 20 72 7e 40…