Currently, there's no check if an invalid buffer range
is passed. However, while testing DVB memory mapped apps,
I got this:
videobuf2_core: VB: num_buffers -2143943680, buffer 33, index -2143943647
unable to handle kernel paging request at ffff888b773c0890
IP: __vb2_queue_alloc+0x134/0x4e0 [videobuf2_core]
PGD 4142c7067 P4D 4142c7067 PUD 0
Oops: 0002 [#1] SMP
Modules linked in: xt_CHECKSUM iptable_mangle ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack tun bridge stp llc ebtable_filter ebtables ip6table_filter ip6_tables bluetooth rfkill ecdh_generic binfmt_misc rc_dvbsky sp2 ts2020 intel_rapl x86_pkg_temp_thermal dvb_usb_dvbsky intel_powerclamp dvb_usb_v2 coretemp m88ds3103 kvm_intel i2c_mux dvb_core snd_hda_codec_hdmi crct10dif_pclmul crc32_pclmul videobuf2_vmalloc videobuf2_memops snd_hda_intel ghash_clmulni_intel videobuf2_core snd_hda_codec rc_core mei_me intel_cstate snd_hwdep snd_hda_core videodev intel_uncore snd_pcm mei media tpm_tis tpm_tis_core intel_rapl_perf tpm snd_timer lpc_ich snd soundcore kvm irqbypass libcrc32c i915 i2c_algo_bit drm_kms_helper
e1000e ptp drm crc32c_intel video pps_core
CPU: 3 PID: 1776 Comm: dvbv5-zap Not tainted 4.14.0+ #78
Hardware name: /NUC5i7RYB, BIOS RYBDWi35.86A.0364.2017.0511.0949 05/11/2017
task: ffff88877c73bc80 task.stack: ffffb7c402418000
RIP: 0010:__vb2_queue_alloc+0x134/0x4e0 [videobuf2_core]
RSP: 0018:ffffb7c40241bc60 EFLAGS: 00010246
RAX: 0000000080360421 RBX: 0000000000000021 RCX: 000000000000000a
RDX: ffffb7c40241bcf4 RSI: ffff888780362c60 RDI: ffff888796d8e130
RBP: ffffb7c40241bcc8 R08: 0000000000000316 R09: 0000000000000004
R10: ffff888780362c00 R11: 0000000000000001 R12: 000000000002f000
R13: ffff8887758be700 R14: 0000000000021000 R15: 0000000000000001
FS: 00007f2849024740(0000) GS:ffff888796d80000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff888b773c0890 CR3: 000000043beb2005 CR4: 00000000003606e0
Call Trace:
vb2_core_reqbufs+0x226/0x420 [videobuf2_core]
dvb_vb2_reqbufs+0x2d/0xc0 [dvb_core]
dvb_dvr_do_ioctl+0x98/0x1d0 [dvb_core]
dvb_usercopy+0x53/0x1b0 [dvb_core]
? dvb_demux_ioctl+0x20/0x20 [dvb_core]
? tty_ldisc_deref+0x16/0x20
? tty_write+0x1f9/0x310
? process_echoes+0x70/0x70
dvb_dvr_ioctl+0x15/0x20 [dvb_core]
do_vfs_ioctl+0xa5/0x600
SyS_ioctl+0x79/0x90
entry_SYSCALL_64_fastpath+0x1a/0xa5
RIP: 0033:0x7f28486f7ea7
RSP: 002b:00007ffc13b2db18 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000055b10fc06130 RCX: 00007f28486f7ea7
RDX: 00007ffc13b2db48 RSI: 00000000c0086f3c RDI: 0000000000000007
RBP: 0000000000000203 R08: 000055b10df1e02c R09: 000000000000002e
R10: 0036b42415108357 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2849062f60 R14: 00000000000001f1 R15: 00007ffc13b2da54
Code: 74 0a 60 8b 0a 48 83 c0 30 48 83 c2 04 89 48 d0 89 48 d4 48 39 f0 75 eb 41 8b 42 08 83 7d d4 01 41 c7 82 ec 01 00 00 ff ff ff ff <4d> 89 94 c5 88 00 00 00 74 14 83 c3 01 41 39 dc 0f 85 f1 fe ff
RIP: __vb2_queue_alloc+0x134/0x4e0 [videobuf2_core] RSP: ffffb7c40241bc60
CR2: ffff888b773c0890
So, add a sanity check in order to prevent going past array.
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>
---
drivers/media/common/videobuf/videobuf2-core.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/media/common/videobuf/videobuf2-core.c b/drivers/media/common/videobuf/videobuf2-core.c
index a8589d96ef72..a3b4836fc41d 100644
--- a/drivers/media/common/videobuf/videobuf2-core.c
+++ b/drivers/media/common/videobuf/videobuf2-core.c
@@ -332,6 +332,9 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
struct vb2_buffer *vb;
int ret;
+ /* Ensure that q->num_buffers+num_buffers is below VB2_MAX_FRAME */
+ num_buffers = min_t(unsigned int, num_buffers, VB2_MAX_FRAME - q->num_buffers);
+
for (buffer = 0; buffer < num_buffers; ++buffer) {
/* Allocate videobuf buffer structures */
vb = kzalloc(q->buf_struct_size, GFP_KERNEL);
--
2.14.3
