Re: UBSAN: array-index-out-of-bounds in alg_bind

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    3cea11cd Linux 5.10-rc2
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1443bf92500000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e791ddf0875adf65
dashboard link: https://syzkaller.appspot.com/bug?extid=92ead4eb8e26a26d465e
compiler:       clang version 11.0.0 (https://github.com/llvm/llvm-project.git ca2dcbd030eadbf0aa9b660efe864ff08af6e18b)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=145afc2c500000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=141ad11a500000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+92ead4eb8e26a26d465e@xxxxxxxxxxxxxxxxxxxxxxxxx

================================================================================
UBSAN: array-index-out-of-bounds in crypto/af_alg.c:166:2
index 98 is out of range for type '__u8 [64]'
CPU: 1 PID: 8468 Comm: syz-executor983 Not tainted 5.10.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x137/0x1be lib/dump_stack.c:118
 ubsan_epilogue lib/ubsan.c:148 [inline]
 __ubsan_handle_out_of_bounds+0xdb/0x130 lib/ubsan.c:356
 alg_bind+0x738/0x740 crypto/af_alg.c:166
 __sys_bind+0x283/0x360 net/socket.c:1656
 __do_sys_bind net/socket.c:1667 [inline]
 __se_sys_bind net/socket.c:1665 [inline]
 __x64_sys_bind+0x76/0x80 net/socket.c:1665
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x4402c9
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 7b 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffe05301528 EFLAGS: 00000246 ORIG_RAX: 0000000000000031
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004402c9
RDX: 000000000000007b RSI: 00000000200000c0 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401ad0
R13: 0000000000401b60 R14: 0000000000000000 R15: 0000000000000000
================================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 8468 Comm: syz-executor983 Not tainted 5.10.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x137/0x1be lib/dump_stack.c:118
 panic+0x291/0x800 kernel/panic.c:231
 ubsan_epilogue lib/ubsan.c:162 [inline]
 __ubsan_handle_out_of_bounds+0x12b/0x130 lib/ubsan.c:356
 alg_bind+0x738/0x740 crypto/af_alg.c:166
 __sys_bind+0x283/0x360 net/socket.c:1656
 __do_sys_bind net/socket.c:1667 [inline]
 __se_sys_bind net/socket.c:1665 [inline]
 __x64_sys_bind+0x76/0x80 net/socket.c:1665
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x4402c9
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 7b 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffe05301528 EFLAGS: 00000246 ORIG_RAX: 0000000000000031
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004402c9
RDX: 000000000000007b RSI: 00000000200000c0 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401ad0
R13: 0000000000401b60 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..