diff options
authorYoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>2013-07-23 11:30:49 +0930
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-08-14 22:59:08 -0700
commit81b80fb88ca579363abebb6da2e7023ffe657203 (patch)
parent4662ffcbe30f95deeae95a7009faa54e1209b466 (diff)
virtio/console: Quit from splice_write if pipe->nrbufs is 0
commit 68c034fefe20eaf7d5569aae84584b07987ce50a upstream. Quit from splice_write if pipe->nrbufs is 0 for avoiding oops in virtio-serial. When an application was doing splice from a kernel buffer to virtio-serial on a guest, the application received signal(SIGINT). This situation will normally happen, but the kernel executed a kernel panic by oops as follows: BUG: unable to handle kernel paging request at ffff882071c8ef28 IP: [<ffffffff812de48f>] sg_init_table+0x2f/0x50 PGD 1fac067 PUD 0 Oops: 0000 [#1] SMP Modules linked in: lockd sunrpc bnep bluetooth rfkill ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 xt_state nf_conntrack ip6table_filter ip6_tables snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_page_alloc snd_timer snd microcode virtio_balloon virtio_net pcspkr soundcore i2c_piix4 i2c_core uinput floppy CPU: 1 PID: 908 Comm: trace-cmd Not tainted 3.10.0+ #49 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007 task: ffff880071c64650 ti: ffff88007bf24000 task.ti: ffff88007bf24000 RIP: 0010:[<ffffffff812de48f>] [<ffffffff812de48f>] sg_init_table+0x2f/0x50 RSP: 0018:ffff88007bf25dd8 EFLAGS: 00010286 RAX: 0000001fffffffe0 RBX: ffff882071c8ef28 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff880071c8ef48 RBP: ffff88007bf25de8 R08: ffff88007fd15d40 R09: ffff880071c8ef48 R10: ffffea0001c71040 R11: ffffffff8139c555 R12: 0000000000000000 R13: ffff88007506a3c0 R14: ffff88007c862500 R15: ffff880071c8ef00 FS: 00007f0a3646c740(0000) GS:ffff88007fd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff882071c8ef28 CR3: 000000007acbb000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Stack: ffff880071c8ef48 ffff88007bf25e20 ffff88007bf25e88 ffffffff8139d6fa ffff88007bf25e28 ffffffff8127a3f4 0000000000000000 0000000000000000 ffff880071c8ef48 0000100000000000 0000000000000003 ffff88007bf25e08 Call Trace: [<ffffffff8139d6fa>] port_fops_splice_write+0xaa/0x130 [<ffffffff8127a3f4>] ? selinux_file_permission+0xc4/0x120 [<ffffffff8139d650>] ? wait_port_writable+0x1b0/0x1b0 [<ffffffff811a6fe0>] do_splice_from+0xa0/0x110 [<ffffffff811a951f>] SyS_splice+0x5ff/0x6b0 [<ffffffff8161f8c2>] system_call_fastpath+0x16/0x1b Code: c1 e2 05 48 89 e5 48 83 ec 10 4c 89 65 f8 41 89 f4 31 f6 48 89 5d f0 48 89 fb e8 8d ce ff ff 41 8d 44 24 ff 48 c1 e0 05 48 01 c3 <48> 8b 03 48 83 e0 fe 48 83 c8 02 48 89 03 48 8b 5d f0 4c 8b 65 RIP [<ffffffff812de48f>] sg_init_table+0x2f/0x50 RSP <ffff88007bf25dd8> CR2: ffff882071c8ef28 ---[ end trace 86323505eb42ea8f ]--- It seems to induce pagefault in sg_init_tabel() when pipe->nrbufs is equal to zero. This may happen in a following situation: (1) The application normally does splice(read) from a kernel buffer, then does splice(write) to virtio-serial. (2) The application receives SIGINT when is doing splice(read), so splice(read) is failed by EINTR. However, the application does not finish the operation. (3) The application tries to do splice(write) without pipe->nrbufs. (4) The virtio-console driver tries to touch scatterlist structure sgl in sg_init_table(), but the region is out of bound. To avoid the case, a kernel should check whether pipe->nrbufs is empty or not when splice_write is executed in the virtio-console driver. V3: Add Reviewed-by lines and stable@ line in sign-off area. Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com> Reviewed-by: Amit Shah <amit.shah@redhat.com> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Amit Shah <amit.shah@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 1b456fe9b87..8722656cdeb 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -932,6 +932,13 @@ static ssize_t port_fops_splice_write(struct pipe_inode_info *pipe,
if (is_rproc_serial(port->out_vq->vdev))
return -EINVAL;
+ /*
+ * pipe->nrbufs == 0 means there are no data to transfer,
+ * so this returns just 0 for no data.
+ */
+ if (!pipe->nrbufs)
+ return 0;
ret = wait_port_writable(port, filp->f_flags & O_NONBLOCK);
if (ret < 0)
return ret;