[PATCH 3.18 44/47] [media] xc2028: avoid use after free

From: Greg Kroah-Hartman
Date: Fri Apr 28 2017 - 04:35:47 EST

3.18-stable review patch. If anyone has any objections, please let me know.

------------------

From: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxx>

commit 8dfbcc4351a0b6d2f2d77f367552f48ffefafe18 upstream.

If struct xc2028_config is passed without a firmware name,
the following trouble may happen:

[11009.907205] xc2028 5-0061: type set to XCeive xc2028/xc3028 tuner
[11009.907491] ==================================================================
[11009.907750] BUG: KASAN: use-after-free in strcmp+0x96/0xb0 at addr ffff8803bd78ab40
[11009.907992] Read of size 1 by task modprobe/28992
[11009.907994] =============================================================================
[11009.907997] BUG kmalloc-16 (Tainted: G W ): kasan: bad access detected
[11009.907999] -----------------------------------------------------------------------------

[11009.908008] INFO: Allocated in xhci_urb_enqueue+0x214/0x14c0 [xhci_hcd] age=0 cpu=3 pid=28992
[11009.908012] ___slab_alloc+0x581/0x5b0
[11009.908014] __slab_alloc+0x51/0x90
[11009.908017] __kmalloc+0x27b/0x350
[11009.908022] xhci_urb_enqueue+0x214/0x14c0 [xhci_hcd]
[11009.908026] usb_hcd_submit_urb+0x1e8/0x1c60
[11009.908029] usb_submit_urb+0xb0e/0x1200
[11009.908032] usb_serial_generic_write_start+0xb6/0x4c0
[11009.908035] usb_serial_generic_write+0x92/0xc0
[11009.908039] usb_console_write+0x38a/0x560
[11009.908045] call_console_drivers.constprop.14+0x1ee/0x2c0
[11009.908051] console_unlock+0x40d/0x900
[11009.908056] vprintk_emit+0x4b4/0x830
[11009.908061] vprintk_default+0x1f/0x30
[11009.908064] printk+0x99/0xb5
[11009.908067] kasan_report_error+0x10a/0x550
[11009.908070] __asan_report_load1_noabort+0x43/0x50
[11009.908074] INFO: Freed in xc2028_set_config+0x90/0x630 [tuner_xc2028] age=1 cpu=3 pid=28992
[11009.908077] __slab_free+0x2ec/0x460
[11009.908080] kfree+0x266/0x280
[11009.908083] xc2028_set_config+0x90/0x630 [tuner_xc2028]
[11009.908086] xc2028_attach+0x310/0x8a0 [tuner_xc2028]
[11009.908090] em28xx_attach_xc3028.constprop.7+0x1f9/0x30d [em28xx_dvb]
[11009.908094] em28xx_dvb_init.part.3+0x8e4/0x5cf4 [em28xx_dvb]
[11009.908098] em28xx_dvb_init+0x81/0x8a [em28xx_dvb]
[11009.908101] em28xx_register_extension+0xd9/0x190 [em28xx]
[11009.908105] em28xx_dvb_register+0x10/0x1000 [em28xx_dvb]
[11009.908108] do_one_initcall+0x141/0x300
[11009.908111] do_init_module+0x1d0/0x5ad
[11009.908114] load_module+0x6666/0x9ba0
[11009.908117] SyS_finit_module+0x108/0x130
[11009.908120] entry_SYSCALL_64_fastpath+0x16/0x76
[11009.908123] INFO: Slab 0xffffea000ef5e280 objects=25 used=25 fp=0x (null) flags=0x2ffff8000004080
[11009.908126] INFO: Object 0xffff8803bd78ab40 @offset=2880 fp=0x0000000000000001

[11009.908130] Bytes b4 ffff8803bd78ab30: 01 00 00 00 2a 07 00 00 9d 28 00 00 01 00 00 00 ....*....(......
[11009.908133] Object ffff8803bd78ab40: 01 00 00 00 00 00 00 00 b0 1d c3 6a 00 88 ff ff ...........j....
[11009.908137] CPU: 3 PID: 28992 Comm: modprobe Tainted: G B W 4.5.0-rc1+ #43
[11009.908140] Hardware name: /NUC5i7RYB, BIOS RYBDWi35.86A.0350.2015.0812.1722 08/12/2015
[11009.908142] ffff8803bd78a000 ffff8802c273f1b8 ffffffff81932007 ffff8803c6407a80
[11009.908148] ffff8802c273f1e8 ffffffff81556759 ffff8803c6407a80 ffffea000ef5e280
[11009.908153] ffff8803bd78ab40 dffffc0000000000 ffff8802c273f210 ffffffff8155ccb4
[11009.908158] Call Trace:
[11009.908162] [<ffffffff81932007>] dump_stack+0x4b/0x64
[11009.908165] [<ffffffff81556759>] print_trailer+0xf9/0x150
[11009.908168] [<ffffffff8155ccb4>] object_err+0x34/0x40
[11009.908171] [<ffffffff8155f260>] kasan_report_error+0x230/0x550
[11009.908175] [<ffffffff81237d71>] ? trace_hardirqs_off_caller+0x21/0x290
[11009.908179] [<ffffffff8155e926>] ? kasan_unpoison_shadow+0x36/0x50
[11009.908182] [<ffffffff8155f5c3>] __asan_report_load1_noabort+0x43/0x50
[11009.908185] [<ffffffff8155ea00>] ? __asan_register_globals+0x50/0xa0
[11009.908189] [<ffffffff8194cea6>] ? strcmp+0x96/0xb0
[11009.908192] [<ffffffff8194cea6>] strcmp+0x96/0xb0
[11009.908196] [<ffffffffa13ba4ac>] xc2028_set_config+0x15c/0x630 [tuner_xc2028]
[11009.908200] [<ffffffffa13bac90>] xc2028_attach+0x310/0x8a0 [tuner_xc2028]
[11009.908203] [<ffffffff8155ea78>] ? memset+0x28/0x30
[11009.908206] [<ffffffffa13ba980>] ? xc2028_set_config+0x630/0x630 [tuner_xc2028]
[11009.908211] [<ffffffffa157a59a>] em28xx_attach_xc3028.constprop.7+0x1f9/0x30d [em28xx_dvb]
[11009.908215] [<ffffffffa157aa2a>] ? em28xx_dvb_init.part.3+0x37c/0x5cf4 [em28xx_dvb]
[11009.908219] [<ffffffffa157a3a1>] ? hauppauge_hvr930c_init+0x487/0x487 [em28xx_dvb]
[11009.908222] [<ffffffffa01795ac>] ? lgdt330x_attach+0x1cc/0x370 [lgdt330x]
[11009.908226] [<ffffffffa01793e0>] ? i2c_read_demod_bytes.isra.2+0x210/0x210 [lgdt330x]
[11009.908230] [<ffffffff812e87d0>] ? ref_module.part.15+0x10/0x10
[11009.908233] [<ffffffff812e56e0>] ? module_assert_mutex_or_preempt+0x80/0x80
[11009.908238] [<ffffffffa157af92>] em28xx_dvb_init.part.3+0x8e4/0x5cf4 [em28xx_dvb]
[11009.908242] [<ffffffffa157a6ae>] ? em28xx_attach_xc3028.constprop.7+0x30d/0x30d [em28xx_dvb]
[11009.908245] [<ffffffff8195222d>] ? string+0x14d/0x1f0
[11009.908249] [<ffffffff8195381f>] ? symbol_string+0xff/0x1a0
[11009.908253] [<ffffffff81953720>] ? uuid_string+0x6f0/0x6f0
[11009.908257] [<ffffffff811a775e>] ? __kernel_text_address+0x7e/0xa0
[11009.908260] [<ffffffff8104b02f>] ? print_context_stack+0x7f/0xf0
[11009.908264] [<ffffffff812e9846>] ? __module_address+0xb6/0x360
[11009.908268] [<ffffffff8137fdc9>] ? is_ftrace_trampoline+0x99/0xe0
[11009.908271] [<ffffffff811a775e>] ? __kernel_text_address+0x7e/0xa0
[11009.908275] [<ffffffff81240a70>] ? debug_check_no_locks_freed+0x290/0x290
[11009.908278] [<ffffffff8104a24b>] ? dump_trace+0x11b/0x300
[11009.908282] [<ffffffffa13e8143>] ? em28xx_register_extension+0x23/0x190 [em28xx]
[11009.908285] [<ffffffff81237d71>] ? trace_hardirqs_off_caller+0x21/0x290
[11009.908289] [<ffffffff8123ff56>] ? trace_hardirqs_on_caller+0x16/0x590
[11009.908292] [<ffffffff812404dd>] ? trace_hardirqs_on+0xd/0x10
[11009.908296] [<ffffffffa13e8143>] ? em28xx_register_extension+0x23/0x190 [em28xx]
[11009.908299] [<ffffffff822dcbb0>] ? mutex_trylock+0x400/0x400
[11009.908302] [<ffffffff810021a1>] ? do_one_initcall+0x131/0x300
[11009.908306] [<ffffffff81296dc7>] ? call_rcu_sched+0x17/0x20
[11009.908309] [<ffffffff8159e708>] ? put_object+0x48/0x70
[11009.908314] [<ffffffffa1579f11>] em28xx_dvb_init+0x81/0x8a [em28xx_dvb]
[11009.908317] [<ffffffffa13e81f9>] em28xx_register_extension+0xd9/0x190 [em28xx]
[11009.908320] [<ffffffffa0150000>] ? 0xffffffffa0150000
[11009.908324] [<ffffffffa0150010>] em28xx_dvb_register+0x10/0x1000 [em28xx_dvb]
[11009.908327] [<ffffffff810021b1>] do_one_initcall+0x141/0x300
[11009.908330] [<ffffffff81002070>] ? try_to_run_init_process+0x40/0x40
[11009.908333] [<ffffffff8123ff56>] ? trace_hardirqs_on_caller+0x16/0x590
[11009.908337] [<ffffffff8155e926>] ? kasan_unpoison_shadow+0x36/0x50
[11009.908340] [<ffffffff8155e926>] ? kasan_unpoison_shadow+0x36/0x50
[11009.908343] [<ffffffff8155e926>] ? kasan_unpoison_shadow+0x36/0x50
[11009.908346] [<ffffffff8155ea37>] ? __asan_register_globals+0x87/0xa0
[11009.908350] [<ffffffff8144da7b>] do_init_module+0x1d0/0x5ad
[11009.908353] [<ffffffff812f2626>] load_module+0x6666/0x9ba0
[11009.908356] [<ffffffff812e9c90>] ? symbol_put_addr+0x50/0x50
[11009.908361] [<ffffffffa1580037>] ? em28xx_dvb_init.part.3+0x5989/0x5cf4 [em28xx_dvb]
[11009.908366] [<ffffffff812ebfc0>] ? module_frob_arch_sections+0x20/0x20
[11009.908369] [<ffffffff815bc940>] ? open_exec+0x50/0x50
[11009.908374] [<ffffffff811671bb>] ? ns_capable+0x5b/0xd0
[11009.908377] [<ffffffff812f5e58>] SyS_finit_module+0x108/0x130
[11009.908379] [<ffffffff812f5d50>] ? SyS_init_module+0x1f0/0x1f0
[11009.908383] [<ffffffff81004044>] ? lockdep_sys_exit_thunk+0x12/0x14
[11009.908394] [<ffffffff822e6936>] entry_SYSCALL_64_fastpath+0x16/0x76
[11009.908396] Memory state around the buggy address:
[11009.908398] ffff8803bd78aa00: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[11009.908401] ffff8803bd78aa80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[11009.908403] >ffff8803bd78ab00: fc fc fc fc fc fc fc fc 00 00 fc fc fc fc fc fc
[11009.908405] ^
[11009.908407] ffff8803bd78ab80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[11009.908409] ffff8803bd78ac00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[11009.908411] ==================================================================

In order to avoid it, let's set the cached value of the firmware
name to NULL after freeing it. While here, return an error if
the memory allocation fails.

Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxx>
Cc: Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/media/tuners/tuner-xc2028.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/media/tuners/tuner-xc2028.c
+++ b/drivers/media/tuners/tuner-xc2028.c
@@ -1403,11 +1403,12 @@ static int xc2028_set_config(struct dvb_
* in order to avoid troubles during device release.
*/
kfree(priv->ctrl.fname);
+ priv->ctrl.fname = NULL;
memcpy(&priv->ctrl, p, sizeof(priv->ctrl));
if (p->fname) {
priv->ctrl.fname = kstrdup(p->fname, GFP_KERNEL);
if (priv->ctrl.fname == NULL)
- rc = -ENOMEM;
+ return -ENOMEM;
}

/*