From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 5DBF71DC759; Tue, 8 Oct 2024 12:37:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728391055; cv=none; b=dc5KNhv6mcj/DgcaMvbI1oy0MhV60V8qsQ4opEl8Athhmp7H6yi+3PN/VyV8xodKh4TBDsnEkW1TjRKLKC0g3n2dLjVORr02QM4aGImOhYukpW0X6DIJqq1PJy01NWvkyb8T3V8B7m9xOwiZpj8xMRVON//lkQsNNDOta/hIP7o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728391055; c=relaxed/simple; bh=7MYeIBKwFVmPP70oLvWrj7jZFCPQtXSMhF720nOanNc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=JD9iIRMW8JTCY4DtIBxjIHtoIUauSUeFGarLVkKQogZEiweLKhfad+WywIGqs5bjItTJqrtCoQE+ONmaC6/kEFNMFJXNJq95CMSUFdfgsVViJdZ1jF49ARpExr3b12Dq+9BwQM3KAZJiNP2mFtBrrBdSZKEGEQ1qRAYYCCCMlbM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=S79og12G; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="S79og12G" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D62FCC4CEC7; Tue, 8 Oct 2024 12:37:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1728391055; bh=7MYeIBKwFVmPP70oLvWrj7jZFCPQtXSMhF720nOanNc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=S79og12GezEz8W3MXTy9kFzOjcEORVa0x7PERtWaQEgmWbdov4R+Y5cjrGLtI9JmI +q3370jHkxuKzGTpMYHC06yAyZOJXw9s6ow4K9ZyGe6rx1ju3iinUdK7z0Y/hOy51c IY8/Qy6JaBYmGYT3g/CTDQC3Jjrx0kRwIyIgFpFA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Haoran Zhang , Mike Christie , "Michael S. Tsirkin" Subject: [PATCH 6.10 477/482] vhost/scsi: null-ptr-dereference in vhost_scsi_get_req() Date: Tue, 8 Oct 2024 14:09:00 +0200 Message-ID: <20241008115707.282070402@linuxfoundation.org> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241008115648.280954295@linuxfoundation.org> References: <20241008115648.280954295@linuxfoundation.org> User-Agent: quilt/0.67 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 6.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Haoran Zhang commit 221af82f606d928ccef19a16d35633c63026f1be upstream. Since commit 3f8ca2e115e5 ("vhost/scsi: Extract common handling code from control queue handler") a null pointer dereference bug can be triggered when guest sends an SCSI AN request. In vhost_scsi_ctl_handle_vq(), `vc.target` is assigned with `&v_req.tmf.lun[1]` within a switch-case block and is then passed to vhost_scsi_get_req() which extracts `vc->req` and `tpg`. However, for a `VIRTIO_SCSI_T_AN_*` request, tpg is not required, so `vc.target` is set to NULL in this branch. Later, in vhost_scsi_get_req(), `vc->target` is dereferenced without being checked, leading to a null pointer dereference bug. This bug can be triggered from guest. When this bug occurs, the vhost_worker process is killed while holding `vq->mutex` and the corresponding tpg will remain occupied indefinitely. Below is the KASAN report: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 1 PID: 840 Comm: poc Not tainted 6.10.0+ #1 Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:vhost_scsi_get_req+0x165/0x3a0 Code: 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 2b 02 00 00 48 b8 00 00 00 00 00 fc ff df 4d 8b 65 30 4c 89 e2 48 c1 ea 03 <0f> b6 04 02 4c 89 e2 83 e2 07 38 d0 7f 08 84 c0 0f 85 be 01 00 00 RSP: 0018:ffff888017affb50 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: ffff88801b000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888017affcb8 RBP: ffff888017affb80 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff888017affc88 R14: ffff888017affd1c R15: ffff888017993000 FS: 000055556e076500(0000) GS:ffff88806b100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000200027c0 CR3: 0000000010ed0004 CR4: 0000000000370ef0 Call Trace: ? show_regs+0x86/0xa0 ? die_addr+0x4b/0xd0 ? exc_general_protection+0x163/0x260 ? asm_exc_general_protection+0x27/0x30 ? vhost_scsi_get_req+0x165/0x3a0 vhost_scsi_ctl_handle_vq+0x2a4/0xca0 ? __pfx_vhost_scsi_ctl_handle_vq+0x10/0x10 ? __switch_to+0x721/0xeb0 ? __schedule+0xda5/0x5710 ? __kasan_check_write+0x14/0x30 ? _raw_spin_lock+0x82/0xf0 vhost_scsi_ctl_handle_kick+0x52/0x90 vhost_run_work_list+0x134/0x1b0 vhost_task_fn+0x121/0x350 ... ---[ end trace 0000000000000000 ]--- Let's add a check in vhost_scsi_get_req. Fixes: 3f8ca2e115e5 ("vhost/scsi: Extract common handling code from control queue handler") Signed-off-by: Haoran Zhang [whitespace fixes] Signed-off-by: Mike Christie Message-Id: Signed-off-by: Michael S. Tsirkin Signed-off-by: Greg Kroah-Hartman --- drivers/vhost/scsi.c | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-) --- a/drivers/vhost/scsi.c +++ b/drivers/vhost/scsi.c @@ -1029,20 +1029,23 @@ vhost_scsi_get_req(struct vhost_virtqueu /* virtio-scsi spec requires byte 0 of the lun to be 1 */ vq_err(vq, "Illegal virtio-scsi lun: %u\n", *vc->lunp); } else { - struct vhost_scsi_tpg **vs_tpg, *tpg; + struct vhost_scsi_tpg **vs_tpg, *tpg = NULL; - vs_tpg = vhost_vq_get_backend(vq); /* validated at handler entry */ - - tpg = READ_ONCE(vs_tpg[*vc->target]); - if (unlikely(!tpg)) { - vq_err(vq, "Target 0x%x does not exist\n", *vc->target); - } else { - if (tpgp) - *tpgp = tpg; - ret = 0; + if (vc->target) { + /* validated at handler entry */ + vs_tpg = vhost_vq_get_backend(vq); + tpg = READ_ONCE(vs_tpg[*vc->target]); + if (unlikely(!tpg)) { + vq_err(vq, "Target 0x%x does not exist\n", *vc->target); + goto out; + } } - } + if (tpgp) + *tpgp = tpg; + ret = 0; + } +out: return ret; }