From: Imre Deak <imre.deak@intel.com> stable inclusion from stable-v5.10.233 commit 109f91d8b9335b0f3714ef9920eae5a8b21d56af category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBEAN5 CVE: CVE-2024-56616 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit bd2fccac61b40eaf08d9546acc9fef958bfe4763 ] Fix the MST sideband message body length check, which must be at least 1 byte accounting for the message body CRC (aka message data CRC) at the end of the message. This fixes a case where an MST branch device returns a header with a correct header CRC (indicating a correctly received body length), with the body length being incorrectly set to 0. This will later lead to a memory corruption in drm_dp_sideband_append_payload() and the following errors in dmesg: UBSAN: array-index-out-of-bounds in drivers/gpu/drm/display/drm_dp_mst_topology.c:786:25 index -1 is out of range for type 'u8 [48]' Call Trace: drm_dp_sideband_append_payload+0x33d/0x350 [drm_display_helper] drm_dp_get_one_sb_msg+0x3ce/0x5f0 [drm_display_helper] drm_dp_mst_hpd_irq_handle_event+0xc8/0x1580 [drm_display_helper] memcpy: detected field-spanning write (size 18446744073709551615) of single field "&msg->msg[msg->curlen]" at drivers/gpu/drm/display/drm_dp_mst_topology.c:791 (size 256) Call Trace: drm_dp_sideband_append_payload+0x324/0x350 [drm_display_helper] drm_dp_get_one_sb_msg+0x3ce/0x5f0 [drm_display_helper] drm_dp_mst_hpd_irq_handle_event+0xc8/0x1580 [drm_display_helper] Cc: <stable@vger.kernel.org> Cc: Lyude Paul <lyude@redhat.com> Reviewed-by: Lyude Paul <lyude@redhat.com> Signed-off-by: Imre Deak <imre.deak@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20241125205314.1725887-1-imre.... Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Yuan Can <yuancan@huawei.com> --- drivers/gpu/drm/drm_dp_mst_topology.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index bb9f2342e96b..e53306ffeb63 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -318,6 +318,9 @@ static bool drm_dp_decode_sideband_msg_hdr(struct drm_dp_sideband_msg_hdr *hdr, hdr->broadcast = (buf[idx] >> 7) & 0x1; hdr->path_msg = (buf[idx] >> 6) & 0x1; hdr->msg_len = buf[idx] & 0x3f; + if (hdr->msg_len < 1) /* min space for body CRC */ + return false; + idx++; hdr->somt = (buf[idx] >> 7) & 0x1; hdr->eomt = (buf[idx] >> 6) & 0x1; -- 2.22.0