| From bippy-1.2.0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@kernel.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2025-37816: mei: vsc: Fix fortify-panic caused by invalid counted_by() use |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| mei: vsc: Fix fortify-panic caused by invalid counted_by() use |
| |
| gcc 15 honors the __counted_by(len) attribute on vsc_tp_packet.buf[] |
| and the vsc-tp.c code is using this in a wrong way. len does not contain |
| the available size in the buffer, it contains the actual packet length |
| *without* the crc. So as soon as vsc_tp_xfer() tries to add the crc to |
| buf[] the fortify-panic handler gets triggered: |
| |
| [ 80.842193] memcpy: detected buffer overflow: 4 byte write of buffer size 0 |
| [ 80.842243] WARNING: CPU: 4 PID: 272 at lib/string_helpers.c:1032 __fortify_report+0x45/0x50 |
| ... |
| [ 80.843175] __fortify_panic+0x9/0xb |
| [ 80.843186] vsc_tp_xfer.cold+0x67/0x67 [mei_vsc_hw] |
| [ 80.843210] ? seqcount_lockdep_reader_access.constprop.0+0x82/0x90 |
| [ 80.843229] ? lockdep_hardirqs_on+0x7c/0x110 |
| [ 80.843250] mei_vsc_hw_start+0x98/0x120 [mei_vsc] |
| [ 80.843270] mei_reset+0x11d/0x420 [mei] |
| |
| The easiest fix would be to just drop the counted-by but with the exception |
| of the ack buffer in vsc_tp_xfer_helper() which only contains enough room |
| for the packet-header, all other uses of vsc_tp_packet always use a buffer |
| of VSC_TP_MAX_XFER_SIZE bytes for the packet. |
| |
| Instead of just dropping the counted-by, split the vsc_tp_packet struct |
| definition into a header and a full-packet definition and use a fixed |
| size buf[] in the packet definition, this way fortify-source buffer |
| overrun checking still works when enabled. |
| |
| The Linux kernel CVE team has assigned CVE-2025-37816 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.8 with commit 566f5ca9768075e453b7b51a397733968df4287d and fixed in 6.12.26 with commit 3e243378f27cc7d11682a3ad720228b0723affa5 |
| Issue introduced in 6.8 with commit 566f5ca9768075e453b7b51a397733968df4287d and fixed in 6.14.5 with commit ac04663c67f244810b3492e9ecd9f7cdbefeca2d |
| Issue introduced in 6.8 with commit 566f5ca9768075e453b7b51a397733968df4287d and fixed in 6.15 with commit 00f1cc14da0f06d2897b8c528df7c7dcf1b8da50 |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2025-37816 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| drivers/misc/mei/vsc-tp.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/3e243378f27cc7d11682a3ad720228b0723affa5 |
| https://git.kernel.org/stable/c/ac04663c67f244810b3492e9ecd9f7cdbefeca2d |
| https://git.kernel.org/stable/c/00f1cc14da0f06d2897b8c528df7c7dcf1b8da50 |
