From nobody Mon Jun 8 04:27:31 2026 Received: from mailgw.kylinos.cn (mailgw.kylinos.cn [124.126.103.232]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7BB043BE147; Tue, 2 Jun 2026 08:04:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=124.126.103.232 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780387473; cv=none; b=DlKoeP3U+32sVb9A9irPSEldSmxrPKVifrMUDjIbpwf/6XyW0ZQUN3kzmXBEfgpxdNoAXn91PTnh/IlQdeY+ZJcP4ppCaZFlI5RdAzFUTHLZv927EWFdxXB+TLMJoCB9roqW364AD4ekQApdG4aK2qNFeQjGzUz0uTZRM0XLfWI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780387473; c=relaxed/simple; bh=OETo9jbPAvqC90MNsOMYY31pyLMfQavt0YIuX8WZ1iU=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=T9JN46WLoZ8wgS71Fj1YYHJEr409VV0jpjC6BeGfGBc6FjxCFI3D+ynBaE0IMdcUVbUFDUObrfVPybO69GQne/XX3FhHajtyT8DqBuMfsJNq7yXMnLHXGPLD8yFgEX/fPh9bRYiVY9QvPCuw46NPUceyLZPHXMXCoGQMdpwORrA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kylinos.cn; spf=pass smtp.mailfrom=kylinos.cn; arc=none smtp.client-ip=124.126.103.232 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kylinos.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kylinos.cn X-UUID: a86d62fa5e5911f1aa26b74ffac11d73-20260602 X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.3.12,REQID:2f781195-e581-4dbf-9a50-258240510d26,IP:0,U RL:0,TC:0,Content:-25,EDM:0,RT:0,SF:0,FILE:0,BULK:0,RULE:Release_Ham,ACTIO N:release,TS:-25 X-CID-META: VersionHash:e7bac3a,CLOUDID:93f029c7c46a1e7e9f12274d0a1f2f49,BulkI D:nil,BulkQuantity:0,Recheck:0,SF:102|850|865|898,TC:nil,Content:0|15|50,E DM:-3,IP:nil,URL:0,File:nil,RT:nil,Bulk:nil,QS:nil,BEC:nil,COL:0,OSI:0,OSA :0,AV:0,LES:1,SPR:NO,DKR:0,DKP:0,BRR:0,BRE:0,ARC:0 X-CID-BVR: 2,SSN|SDN X-CID-BAS: 2,SSN|SDN,0,_ X-CID-FACTOR: TF_CID_SPAM_SNR X-CID-RHF: D41D8CD98F00B204E9800998ECF8427E X-UUID: a86d62fa5e5911f1aa26b74ffac11d73-20260602 X-User: zenghongling@kylinos.cn Received: from localhost.localdomain [(10.44.16.150)] by mailgw.kylinos.cn (envelope-from ) (Generic MTA with TLSv1.3 TLS_AES_256_GCM_SHA384 256/256) with ESMTP id 369047598; Tue, 02 Jun 2026 16:04:19 +0800 From: Hongling Zeng To: deller@gmx.de, kees@kernel.org Cc: linux-omap@vger.kernel.org, linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, zhongling0719@126.com, Hongling Zeng , stable@vger.kernel.org Subject: [PATCH] fbdev: omap2: fix use-after-free in omapfb_mmap Date: Tue, 2 Jun 2026 16:04:15 +0800 Message-Id: <20260602080415.171378-1-zenghongling@kylinos.cn> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" omapfb_mmap() has a race condition with OMAPFB_SETUP_PLANE ioctl that can lead to use-after-free: The fb_mmap() entry point holds mm_lock but not lock (fb_info->lock), while ioctl handlers like OMAPFB_SETUP_PLANE hold lock but not mm_lock. This allows concurrent execution. In omapfb_mmap(): 1. rg =3D omapfb_get_mem_region(ofbi->region); // Get old region ref 2. start =3D omapfb_get_region_paddr(ofbi); // Read from NEW region 3. len =3D fix->smem_len; // Read from NEW regi= on 4. vm_iomap_memory(vma, start, len); // Map NEW region memory 5. atomic_inc(&rg->map_count); // Increment OLD region! Concurrently, OMAPFB_SETUP_PLANE can: - Reassign ofbi->region =3D new_rg - Update fix->smem_len - OMAPFB_SETUP_MEM then checks NEW region's map_count (0!) and frees it This leaves userspace with a mapping to freed physical memory. The fix is to read all required values (start, len) from the same region reference (rg) that will have its map_count incremented, preventing the region from being freed while still mapped. Cc: stable@vger.kernel.org Signed-off-by: Hongling Zeng --- drivers/video/fbdev/omap2/omapfb/omapfb-main.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/video/fbdev/omap2/omapfb/omapfb-main.c b/drivers/video= /fbdev/omap2/omapfb/omapfb-main.c index d70deb6a9150..853bd55621ec 100644 --- a/drivers/video/fbdev/omap2/omapfb/omapfb-main.c +++ b/drivers/video/fbdev/omap2/omapfb/omapfb-main.c @@ -1099,8 +1099,11 @@ static int omapfb_mmap(struct fb_info *fbi, struct v= m_area_struct *vma) =20 rg =3D omapfb_get_mem_region(ofbi->region); =20 - start =3D omapfb_get_region_paddr(ofbi); - len =3D fix->smem_len; + if (ofbi->rotation_type =3D=3D OMAP_DSS_ROT_VRFB) + start =3D rg->vrfb.paddr[0]; + else + start =3D rg->paddr; + len =3D rg->size; =20 DBG("user mmap region start %lx, len %d, off %lx\n", start, len, vma->vm_pgoff << PAGE_SHIFT); --=20 2.25.1