From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 0132A3D8916; Tue, 13 Oct 2026 12:10:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791893446; cv=none; b=HlRyU1uGDfkZUg8jdFcDhsJrO1LwMkzlxIeujzjbCLPv29SCL9ySkXckKqxtfViggyv1uQZCpWDnVXDm0fewKDFTY2NDcqawCyUKSNHU6gWqQq/OTA7SxRPZvvGRhN00ODZKVgKbK2/RLi5+fp3WXGfwzkisKlF4KQW4IknNdfY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791893446; c=relaxed/simple; bh=QW2C5HOt0OIintUDdXsmQmWlQ6AX3/2CSOlPYh/rt0I=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hmbyt7AxUGL8/VZ0xDTophoGXAYumnrV5G4n/78OG62W3+57lR7OVvkacPszvCR3BKX2VsuHt6fTvHdCh+E5dCd9spIkoOvLmDC9Tdhsl2hjDBFPUqJ/oMZpT3/et0occRbyLg40QxIcp/CuRR9l1XyGnU/VMgJQP1DHx5YZv5E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=xf3qaH7c; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="xf3qaH7c" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 470641F000FF; Tue, 13 Oct 2026 12:10:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1791893444; bh=pxKxoz7DTmljYKErbErBzana54boJRS9vgGvSbPiULs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=xf3qaH7cK3AfgeChmOtjpYSO1ek1jVh+48oLZ40Gb+q+az/DSUR6PE6KBNfdMdrqR YWe9uCg1nEy4TlbMwfhl1r/01kBhtGjOLKqH9MtnxGyWIzNgOZBXLDjScxGnGf+Z6a yq2CrAb/yPysr3CobujYXIA+iKpmGaugMKsHkNLw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Hongling Zeng , Helge Deller , Sasha Levin Subject: [PATCH 6.18 228/621] fbdev: omap2: fix use-after-free in omapfb_mmap Date: Tue, 13 Oct 2026 13:33:43 +0200 Message-ID: <20261013112926.268163384@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261013112920.855194808@linuxfoundation.org> References: <20261013112920.855194808@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hongling Zeng [ Upstream commit 7958e67375aa111522086286bba13cfc0816ce8d ] 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 = omapfb_get_mem_region(ofbi->region); // Get old region ref 2. start = omapfb_get_region_paddr(ofbi); // Read from NEW region 3. len = fix->smem_len; // Read from NEW region 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 = 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 Signed-off-by: Helge Deller Signed-off-by: Sasha Levin --- drivers/video/fbdev/omap2/omapfb/omapfb-main.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/video/fbdev/omap2/omapfb/omapfb-main.c b/drivers/video/fbdev/omap2/omapfb/omapfb-main.c index 79688c2cc6d68..2b99a58ad6758 100644 --- a/drivers/video/fbdev/omap2/omapfb/omapfb-main.c +++ b/drivers/video/fbdev/omap2/omapfb/omapfb-main.c @@ -1099,7 +1099,11 @@ static int omapfb_mmap(struct fb_info *fbi, struct vm_area_struct *vma) rg = omapfb_get_mem_region(ofbi->region); - start = omapfb_get_region_paddr(ofbi); + if (ofbi->rotation_type == OMAP_DSS_ROT_VRFB) + start = rg->vrfb.paddr[0]; + else + start = rg->paddr; + len = fix->smem_len; DBG("user mmap region start %lx, len %d, off %lx\n", start, len, @@ -1109,6 +1113,8 @@ static int omapfb_mmap(struct fb_info *fbi, struct vm_area_struct *vma) vma->vm_ops = &mmap_user_ops; vma->vm_private_data = rg; + atomic_inc(&rg->map_count); + r = vm_iomap_memory(vma, start, len); if (r) goto error; @@ -1121,6 +1127,7 @@ static int omapfb_mmap(struct fb_info *fbi, struct vm_area_struct *vma) return 0; error: + atomic_dec(&rg->map_count); omapfb_put_mem_region(rg); return r; -- 2.53.0