V4L/DVB (13989): [TDA8261] Fix TDA8261 I2C read bug

The TDA8261 driver would crash when reading more than a byte as described.

ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff
[ 8.430350] KNC1-2: MAC addr = 00:09:d6:65:2d:91
[ 8.610008] saa7146 (1) saa7146_i2c_writeout [irq]: timed out waiting for end of xfer
[ 8.734457] stb0899_attach: Attaching STB0899
[ 8.768481] tda8261_attach: Attaching TDA8261 8PSK/QPSK tuner
[ 8.768485] DVB: registering adapter 2 frontend 0 (STB0899 Multistandard)...

Once I launch scan-s2:
scan-s2 -vvvv -a 2 -s 1 -l UNIVERSAL /usr/share/dvb/dvb-s/Hotbird-13.0E

I see the following via dmesg:

[ 435.040017] saa7146 (1) saa7146_i2c_writeout [irq]: timed out waiting for end of xfer
[ 435.778648] tda8261_get_bandwidth: Bandwidth=40000000
[ 435.781781] tda8261_get_bandwidth: Bandwidth=40000000
[ 435.783311] tda8261_set_state: Step size=1, Divider=1000, PG=0x793 (1939)
[ 435.783512] tda8261_set_state: Waiting to Phase LOCK
[ 435.810134] tda8261_get_status: Tuner Phase Locked
[ 435.810137] tda8261_set_state: Tuner Phase locked: status=1
[ 435.810139] tda8261_set_frequency: Frequency=1939000
[ 435.810141] tda8261_get_frequency: Frequency=7574
[ 435.830008] tda8261_get_bandwidth: Bandwidth=40000000
[ 436.402814] tda8261_get_bandwidth: Bandwidth=40000000
[ 436.405946] tda8261_get_bandwidth: Bandwidth=40000000
[ 436.407458] general protection fault: 0000 [#1] SMP
[ 436.407527] last sysfs file: /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
[ 436.407560] CPU 0
[ 436.407601] Modules linked in: tda8261 stb0899 dvb_pll mt352 lnbp21 budget_av saa7146_vv snd_hda_codec_realtek videodev stv0299 v4l1_compat coretemp snd_hda_intel v4l2_compat_ioctl32 i915 videobuf_dma_sg b2c2_flexcop_pci snd_hda_codec budget_ci videobuf_core b2c2_flexcop ir_common w83627ehf drm snd_hwdep cx24123 budget_core hwmon_vid snd_pcm cx24113 dvb_core iptable_filter snd_timer i2c_algo_bit ip_tables saa7146 s5h1420 snd ttpci_eeprom soundcore intel_agp video serio_raw pcspkr lp snd_page_alloc x_tables output parport pata_it8213 e1000e
[ 436.408757] Pid: 1410, comm: kdvb-ad-2-fe-0 Not tainted 2.6.31-14-server #48-Ubuntu C2SBC-Q
[ 436.408818] RIP: 0010:[<ffffffffa00241a1>] [<ffffffffa00241a1>] tda8261_set_state+0x51/0x250 [tda8261]
[ 436.408903] RSP: 0018:ffff88013649bc70 EFLAGS: 00010283
[ 436.408945] RAX: 00000000000f1748 RBX: ffff880138870680 RCX: 0000000000000018
[ 436.408990] RDX: ffff88013649bcd0 RSI: 0000000000000001 RDI: ffff880135273010
[ 436.409035] RBP: ffff88013649bcc0 R08: 0000000000000001 R09: 0000000000000002
[ 436.409081] R10: ffff88013649bc40 R11: 0000000055555556 R12: 00000000001d9638
[ 436.409126] R13: 38ffffffa0261568 R14: 0000000000000000 R15: ffff880135273010
[ 436.409172] FS: 0000000000000000(0000) GS:ffff880028022000(0000) knlGS:0000000000000000
[ 436.409232] CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b
[ 436.409274] CR2: 00007fff925e4cd8 CR3: 000000013642a000 CR4: 00000000000406f0
[ 436.409320] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 436.409365] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[ 436.409411] Process kdvb-ad-2-fe-0 (pid: 1410, threadinfo ffff88013649a000, task ffff88013658ad60)
[ 436.409473] Stack:
[ 436.409508] ffff880136ee2af1 00000000bcd5d166 ffff000200000068 0000000035273000
[ 436.409608] <0> 0000000000000001 ffff880135273000 ffffffffa0265260 00003473bc000000
[ 436.409758] <0> 0000000000000000 ffff88013a4e05e0 ffff88013649bd00 ffffffffa025f133
[ 436.409938] Call Trace:
[ 436.409978] [<ffffffffa025f133>] tda8261_set_frequency+0x23/0x70 [budget_av]
[ 436.410027] [<ffffffffa026ed09>] ? stb0899_i2c_gate_ctrl+0x49/0xf0 [stb0899]
[ 436.410074] [<ffffffffa026e259>] ? stb0899_write_reg+0x19/0x20 [stb0899]
[ 436.410121] [<ffffffffa02716e2>] stb0899_dvbs_algo+0x3a2/0x13c8 [stb0899]
[ 436.410170] [<ffffffff813cdd0d>] ? i2c_transfer+0xbd/0x100
[ 436.410215] [<ffffffffa026e13c>] ? stb0899_write_regs+0xac/0x1b0 [stb0899]
[ 436.410262] [<ffffffffa026f239>] stb0899_search+0x489/0x750 [stb0899]
[ 436.410308] [<ffffffff8107d153>] ? down_interruptible+0x33/0x60
[ 436.410360] [<ffffffffa00c34ec>] dvb_frontend_thread+0x57c/0x720 [dvb_core]
[ 436.410407] [<ffffffff81078620>] ? autoremove_wake_function+0x0/0x40
[ 436.410457] [<ffffffffa00c2f70>] ? dvb_frontend_thread+0x0/0x720 [dvb_core]
[ 436.410504] [<ffffffff81078236>] kthread+0xa6/0xb0
[ 436.410547] [<ffffffff810130aa>] child_rip+0xa/0x20
[ 436.410589] [<ffffffff81078190>] ? kthread+0x0/0xb0
[ 436.410631] [<ffffffff810130a0>] ? child_rip+0x0/0x20
[ 436.410672] Code: 00 03 00 00 4c 8b 6b 10 c7 45 cc 00 00 00 00 0f 84 e8 01 00 00 44 8b 22 41 8d 84 24 10 81 f1 ff 3d 80 4f 12 00 0f 87 af 01 00 00 <41> 8b 75 04 31 d2 48 c7 c7 d8 46 02 a0 89 f0 8b 0c 85 f0 45 02
[ 436.411950] RIP [<ffffffffa00241a1>] tda8261_set_state+0x51/0x250 [tda8261]
[ 436.412015] RSP <ffff88013649bc70>
[ 436.412064] ---[ end trace c1d7ae4d9e05c51b ]---
Signed-off-by: Arvo Järve <arvo@softshark.ee>
Signed-off-by: Manu Abraham <manu@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/dvb/frontends/tda8261.c

@@ -39,7 +39,7 @@ static int tda8261_read(struct tda8261_state *state, u8 *buf)
 {
 	const struct tda8261_config *config = state->config;
 	int err = 0;
-	struct i2c_msg msg = { .addr	= config->addr, .flags = I2C_M_RD,.buf = buf,  .len = 2 };
+	struct i2c_msg msg = { .addr	= config->addr, .flags = I2C_M_RD,.buf = buf,  .len = 1 };
 
 	if ((err = i2c_transfer(state->i2c, &msg, 1)) != 1)
 		printk("%s: read error, err=%d\n", __func__, err);