CVE-2025-37761

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

drm/xe: Fix an out-of-bounds shift when invalidating TLB

When the size of the range invalidated is larger than rounddown_pow_of_two(ULONG_MAX), The function macro roundup_pow_of_two(length) will hit an out-of-bounds shift [1].

Use a full TLB invalidation for such cases. v2:

• Use a define for the range size limit over which we use a full TLB invalidation. (Lucas)
• Use a better calculation of the limit.

[1]: [ 39.202421] ————[ cut here ]———— [ 39.202657] UBSAN: shift-out-of-bounds in ./include/linux/log2.h:57:13 [ 39.202673] shift exponent 64 is too large for 64-bit type long unsigned int [ 39.202688] CPU: 8 UID: 0 PID: 3129 Comm: xe_exec_system_ Tainted: G U 6.14.0+ #10 [ 39.202690] Tainted: [U]=USER [ 39.202690] Hardware name: ASUS System Product Name/PRIME B560M-A AC, BIOS 2001 02/01/2023 [ 39.202691] Call Trace: [ 39.202692] [ 39.202695] dump_stack_lvl+0x6e/0xa0 [ 39.202699] ubsan_epilogue+0x5/0x30 [ 39.202701] __ubsan_handle_shift_out_of_bounds.cold+0x61/0xe6 [ 39.202705] xe_gt_tlb_invalidation_range.cold+0x1d/0x3a [xe] [ 39.202800] ? find_held_lock+0x2b/0x80 [ 39.202803] ? mark_held_locks+0x40/0x70 [ 39.202806] xe_svm_invalidate+0x459/0x700 [xe] [ 39.202897] drm_gpusvm_notifier_invalidate+0x4d/0x70 [drm_gpusvm] [ 39.202900] __mmu_notifier_release+0x1f5/0x270 [ 39.202905] exit_mmap+0x40e/0x450 [ 39.202912] __mmput+0x45/0x110 [ 39.202914] exit_mm+0xc5/0x130 [ 39.202916] do_exit+0x21c/0x500 [ 39.202918] ? lockdep_hardirqs_on_prepare+0xdb/0x190 [ 39.202920] do_group_exit+0x36/0xa0 [ 39.202922] get_signal+0x8f8/0x900 [ 39.202926] arch_do_signal_or_restart+0x35/0x100 [ 39.202930] syscall_exit_to_user_mode+0x1fc/0x290 [ 39.202932] do_syscall_64+0xa1/0x180 [ 39.202934] ? do_user_addr_fault+0x59f/0x8a0 [ 39.202937] ? lock_release+0xd2/0x2a0 [ 39.202939] ? do_user_addr_fault+0x5a9/0x8a0 [ 39.202942] ? trace_hardirqs_off+0x4b/0xc0 [ 39.202944] ? clear_bhb_loop+0x25/0x80 [ 39.202946] ? clear_bhb_loop+0x25/0x80 [ 39.202947] ? clear_bhb_loop+0x25/0x80 [ 39.202950] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 39.202952] RIP: 0033:0x7fa945e543e1 [ 39.202961] Code: Unable to access opcode bytes at 0x7fa945e543b7. [ 39.202962] RSP: 002b:00007ffca8fb4170 EFLAGS: 00000293 [ 39.202963] RAX: 000000000000003d RBX: 0000000000000000 RCX: 00007fa945e543e3 [ 39.202964] RDX: 0000000000000000 RSI: 00007ffca8fb41ac RDI: 00000000ffffffff [ 39.202964] RBP: 00007ffca8fb4190 R08: 0000000000000000 R09: 00007fa945f600a0 [ 39.202965] R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000 [ 39.202966] R13: 00007fa9460dd310 R14: 00007ffca8fb41ac R15: 0000000000000000 [ 39.202970] [ 39.202970] —[ end trace ]—

(cherry picked from commit b88f48f86500bc0b44b4f73ac66d500a40d320ad)

Weakness

The product reads data past the end, or before the beginning, of the intended buffer.

Affected Software

Potential Mitigations

• Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
• When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
• Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
• To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/540.html

References

• https://git.kernel.org/stable/c/28477f701b63922ff88e9fb13f5519c11cd48b86
• https://git.kernel.org/stable/c/7bcfeddb36b77f9fe3b010bb0b282b7618420bba
• https://git.kernel.org/stable/c/e4715858f87b78ce58cfa03bbe140321edbbaf20