bisecting fixing commit since 59456c9cc40c8f75b5a7efa0fe1f211d9c6fcaf1 building syzkaller on a2fe1cb58994e43fb14f141ecd6e6dcce9bb697a testing commit 59456c9cc40c8f75b5a7efa0fe1f211d9c6fcaf1 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 1172c5799cb83c106a149e8a84166ad15481bb567c5dd9a308a5f6e2f143d639 all runs: crashed: divide error in snd_pcm_lib_ioctl testing current HEAD b172b44fcb1771e083aad806fa96f3f60e2ddfac testing commit b172b44fcb1771e083aad806fa96f3f60e2ddfac compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 7e9d2161af5a0d915a9a41f184582fdd81877d50a21603e1f0f1d482f1450c24 all runs: crashed: divide error in snd_pcm_lib_ioctl revisions tested: 2, total time: 26m11.194823878s (build: 19m7.224106704s, test: 6m41.549664241s) the crash still happens on HEAD commit msg: Linux 4.19.206 crash: divide error in snd_pcm_lib_ioctl IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50 wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50 divide error: 0000 [#1] PREEMPT SMP KASAN ieee80211 phy8: Selected rate control algorithm 'minstrel_ht' CPU: 0 PID: 9836 Comm: syz-executor.2 Not tainted 4.19.206-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready RIP: 0010:snd_pcm_lib_ioctl_fifo_size sound/core/pcm_lib.c:1754 [inline] RIP: 0010:snd_pcm_lib_ioctl+0x3cb/0x8b0 sound/core/pcm_lib.c:1779 Code: c0 7e 32 48 ba 00 00 00 00 00 fc ff df 4c 89 e9 48 c1 e9 03 80 3c 11 00 0f 85 44 04 00 00 89 c1 49 8b 84 24 18 02 00 00 31 d2 <48> f7 f1 49 89 84 24 18 02 00 00 48 83 c4 08 45 31 ed 5b 44 89 e8 RSP: 0018:ffff88808f6efb60 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 000000000000000f RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000040000000 RDI: ffffffff8a6fcd35 RBP: ffff88808f6efb88 R08: fffffbfff13c827d R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a1043b40 R13: ffff8880a1043d58 R14: 0000000000000000 R15: 00000000c1004110 FS: 00007f1e4598f700(0000) GS:ffff8880ba200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffd80b2c038 CR3: 0000000098876000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ieee80211 phy9: Selected rate control algorithm 'minstrel_ht' fixup_unreferenced_params+0x49a/0x700 sound/core/pcm_native.c:496 wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50 snd_pcm_hw_refine_old_user sound/core/pcm_native.c:3600 [inline] snd_pcm_common_ioctl+0x6c5/0x1bf0 sound/core/pcm_native.c:2948 snd_pcm_ioctl+0x66/0xb0 sound/core/pcm_native.c:2985 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0x196/0x10c0 fs/ioctl.c:688 ksys_ioctl+0x62/0x90 fs/ioctl.c:705 wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50 __do_sys_ioctl fs/ioctl.c:712 [inline] __se_sys_ioctl fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:710 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4665e9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f1e4598f188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665e9 RDX: 00000000200010c0 RSI: 00000000c1004110 RDI: 0000000000000003 RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80 R13: 00007ffebf58682f R14: 00007f1e4598f300 R15: 0000000000022000 Modules linked in: ---[ end trace bedfe9af94b4cc13 ]--- IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready RIP: 0010:snd_pcm_lib_ioctl_fifo_size sound/core/pcm_lib.c:1754 [inline] RIP: 0010:snd_pcm_lib_ioctl+0x3cb/0x8b0 sound/core/pcm_lib.c:1779 Code: c0 7e 32 48 ba 00 00 00 00 00 fc ff df 4c 89 e9 48 c1 e9 03 80 3c 11 00 0f 85 44 04 00 00 89 c1 49 8b 84 24 18 02 00 00 31 d2 <48> f7 f1 49 89 84 24 18 02 00 00 48 83 c4 08 45 31 ed 5b 44 89 e8 IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready RSP: 0018:ffff88808f6efb60 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 000000000000000f RCX: 0000000000000000 IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready RDX: 0000000000000000 RSI: 0000000040000000 RDI: ffffffff8a6fcd35 wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50 wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50 wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50 IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50 RBP: ffff88808f6efb88 R08: fffffbfff13c827d R09: 0000000000000000 IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a1043b40 divide error: 0000 [#2] PREEMPT SMP KASAN R13: ffff8880a1043d58 R14: 0000000000000000 R15: 00000000c1004110 CPU: 0 PID: 9863 Comm: syz-executor.0 Tainted: G D 4.19.206-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:snd_pcm_lib_ioctl_fifo_size sound/core/pcm_lib.c:1754 [inline] RIP: 0010:snd_pcm_lib_ioctl+0x3cb/0x8b0 sound/core/pcm_lib.c:1779 Code: c0 7e 32 48 ba 00 00 00 00 00 fc ff df 4c 89 e9 48 c1 e9 03 80 3c 11 00 0f 85 44 04 00 00 89 c1 49 8b 84 24 18 02 00 00 31 d2 <48> f7 f1 49 89 84 24 18 02 00 00 48 83 c4 08 45 31 ed 5b 44 89 e8 FS: 00007f1e4598f700(0000) GS:ffff8880ba300000(0000) knlGS:0000000000000000 RSP: 0018:ffff88808ec47b60 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 000000000000000f RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000040000000 RDI: ffffffff8a6fcd35 RBP: ffff88808ec47b88 R08: 0000000000000058 R09: 000000007c339d8e R10: 00000000335de375 R11: 0000000000000000 R12: ffff888097fe9200 R13: ffff888097fe9418 R14: 0000000000000000 R15: 00000000c1004110 FS: 00007f7940cfc700(0000) GS:ffff8880ba200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000005173f0 CR3: 0000000098888000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: fixup_unreferenced_params+0x49a/0x700 sound/core/pcm_native.c:496 snd_pcm_hw_refine_old_user sound/core/pcm_native.c:3600 [inline] snd_pcm_common_ioctl+0x6c5/0x1bf0 sound/core/pcm_native.c:2948 snd_pcm_ioctl+0x66/0xb0 sound/core/pcm_native.c:2985 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0x196/0x10c0 fs/ioctl.c:688 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 ksys_ioctl+0x62/0x90 fs/ioctl.c:705 __do_sys_ioctl fs/ioctl.c:712 [inline] __se_sys_ioctl fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:710 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe CR2: 00007ffdd95fbf6c CR3: 0000000098876000 CR4: 00000000001406e0 RIP: 0033:0x4665e9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f7940cfc188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665e9 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 RDX: 00000000200010c0 RSI: 00000000c1004110 RDI: 0000000000000003 RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80 R13: 00007ffd6c65171f R14: 00007f7940cfc300 R15: 0000000000022000 Modules linked in: divide error: 0000 [#3] PREEMPT SMP KASAN DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 CPU: 0 PID: 9881 Comm: syz-executor.4 Tainted: G D 4.19.206-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:snd_pcm_lib_ioctl_fifo_size sound/core/pcm_lib.c:1754 [inline] RIP: 0010:snd_pcm_lib_ioctl+0x3cb/0x8b0 sound/core/pcm_lib.c:1779 Code: c0 7e 32 48 ba 00 00 00 00 00 fc ff df 4c 89 e9 48 c1 e9 03 80 3c 11 00 0f 85 44 04 00 00 89 c1 49 8b 84 24 18 02 00 00 31 d2 <48> f7 f1 49 89 84 24 18 02 00 00 48 83 c4 08 45 31 ed 5b 44 89 e8 RSP: 0018:ffff888096f8fb60 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 000000000000000f RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000040000000 RDI: ffffffff8a6fcd35 RBP: ffff888096f8fb88 R08: 0000000000000058 R09: 000000007c339d8e R10: 00000000335de375 R11: 0000000000000000 R12: ffff888096ecb6c0 R13: ffff888096ecb8d8 R14: 0000000000000000 R15: 00000000c1004110 FS: 00007fcc4f3a8700(0000) GS:ffff8880ba200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000005173f0 CR3: 0000000097e20000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: fixup_unreferenced_params+0x49a/0x700 sound/core/pcm_native.c:496 snd_pcm_hw_refine_old_user sound/core/pcm_native.c:3600 [inline] snd_pcm_common_ioctl+0x6c5/0x1bf0 sound/core/pcm_native.c:2948 ieee80211 phy10: Selected rate control algorithm 'minstrel_ht' snd_pcm_ioctl+0x66/0xb0 sound/core/pcm_native.c:2985 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0x196/0x10c0 fs/ioctl.c:688 ---------------- Code disassembly (best guess), 1 bytes skipped: 0: 7e 32 jle 0x34 2: 48 ba 00 00 00 00 00 movabs $0xdffffc0000000000,%rdx 9: fc ff df c: 4c 89 e9 mov %r13,%rcx f: 48 c1 e9 03 shr $0x3,%rcx 13: 80 3c 11 00 cmpb $0x0,(%rcx,%rdx,1) 17: 0f 85 44 04 00 00 jne 0x461 1d: 89 c1 mov %eax,%ecx 1f: 49 8b 84 24 18 02 00 mov 0x218(%r12),%rax 26: 00 27: 31 d2 xor %edx,%edx * 29: 48 f7 f1 div %rcx <-- trapping instruction 2c: 49 89 84 24 18 02 00 mov %rax,0x218(%r12) 33: 00 34: 48 83 c4 08 add $0x8,%rsp 38: 45 31 ed xor %r13d,%r13d 3b: 5b pop %rbx 3c: 44 89 e8 mov %r13d,%eax