Le mardi 19 janvier 2021, 19:39:17 CET syzbot a écrit : > Hello, > > syzbot found the following issue on: > > HEAD commit: 1e2a199f Merge tag 'spi-fix-v5.11-rc4' of git://git.kernel.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=146e0c94d00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=41e68e7e8a23ad09 > dashboard link: https://syzkaller.appspot.com/bug?extid=42d8c7c3d3e594b34346 > compiler: gcc (GCC) 10.1.0-syz 20200507 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12166d58d00000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14dfc294d00000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+42d8c7c3d3e594b34346@xxxxxxxxxxxxxxxxxxxxxxxxx > > ============================================================================ > ==== UBSAN: shift-out-of-bounds in > drivers/media/v4l2-core/v4l2-ctrls.c:2168:36 shift exponent 100 is too > large for 64-bit type 'long long unsigned int' CPU: 0 PID: 8469 Comm: > syz-executor534 Not tainted 5.11.0-rc4-syzkaller #0 Hardware name: Google > Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call > Trace: > __dump_stack lib/dump_stack.c:79 [inline] > dump_stack+0x107/0x163 lib/dump_stack.c:120 > ubsan_epilogue+0xb/0x5a lib/ubsan.c:148 > __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:395 > std_validate.cold+0x19/0x1e drivers/media/v4l2-core/v4l2-ctrls.c:2168 > validate_new drivers/media/v4l2-core/v4l2-ctrls.c:2477 [inline] > set_ctrl+0x207/0x4a0 drivers/media/v4l2-core/v4l2-ctrls.c:4425 > set_ctrl_lock drivers/media/v4l2-core/v4l2-ctrls.c:4448 [inline] > v4l2_s_ctrl+0x2fd/0x4f0 drivers/media/v4l2-core/v4l2-ctrls.c:4469 > v4l_s_ctrl+0x324/0x390 drivers/media/v4l2-core/v4l2-ioctl.c:2253 > __video_do_ioctl+0xb94/0xe20 drivers/media/v4l2-core/v4l2-ioctl.c:2993 > video_usercopy+0x23d/0x12d0 drivers/media/v4l2-core/v4l2-ioctl.c:3345 > v4l2_ioctl+0x1b3/0x250 drivers/media/v4l2-core/v4l2-dev.c:360 > vfs_ioctl fs/ioctl.c:48 [inline] > __do_sys_ioctl fs/ioctl.c:753 [inline] > __se_sys_ioctl fs/ioctl.c:739 [inline] > __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 > do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > RIP: 0033:0x443ee9 > Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff > ff 0f 83 fb d7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: > 002b:00007ffe02e7df08 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: > ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000443ee9 > RDX: 0000000020000140 RSI: 00000000c008561c RDI: 0000000000000003 > RBP: 00000000006ce018 R08: 0000000000000000 R09: 00000000004002e0 > R10: 000000000000000f R11: 0000000000000246 R12: 0000000000401b70 > R13: 0000000000401c00 R14: 0000000000000000 R15: 0000000000000000 > ============================================================================ > ==== > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > syzbot can test patches for this issue, for details see: > https://goo.gl/tpsmEJ#testing-patches Hi everyone. First, I hope you are fine and the same for your relative. I took a look at this bug, unfortunately I do not come with a solution as I lack some background on V4L2. First, I successfully reproduced the bug with the given test and configuration inside a virtual machine. >From my understanding, the test do an ioctl with the flag VIDIOC_S_CTRL and the value 100 as argument. Inside the std_validate() function, ctrl->maximum is 110 as it corresponds to this line inside the vivid_create_controls() function: vivid_ctrl_dv_timings.max = dev->query_dv_timings_size - 1; dev->query_dv_timings_size is set inside vivid_init_dv_timings() based on the v4l2_dv_timings_presets[] which contains 110 values. As a solution, I suggest to change the type of menu_skip_mask inside the struct v4l2_ctrl and replacing it with a bitmap. Indeed, the above value has 110 "menus", so the 64 bits inside menu_skip_mask are too few. This change needs a bit of work as all the usage of menu_skip_mask will need to be adapted to the bitmap API. Unfortunately, I am not sure this solution is the good one so this I why I did not implement it. If someone also looked at this bug and has some feedback I will be happy to hear from it. Best regards.
