KASAN: null-ptr-deref Write in build_segment_manager

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cbfa1702 Linux 4.14.198
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16a11c7d900000
kernel config: https://syzkaller.appspot.com/x/.config?x=3990958d85b55e59
dashboard link: https://syzkaller.appspot.com/bug?extid=157511ba2b871accf7b5
compiler: gcc (GCC) 10.1.0-syz 20200507

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+157511...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: null-ptr-deref in memcpy include/linux/string.h:372 [inline]
BUG: KASAN: null-ptr-deref in build_sit_entries fs/f2fs/segment.c:3289 [inline]
BUG: KASAN: null-ptr-deref in build_segment_manager+0x4fd2/0x7f40 fs/f2fs/segment.c:3564
Write of size 64 at addr (null) by task syz-executor.0/30539

CPU: 0 PID: 30539 Comm: syz-executor.0 Not tainted 4.14.198-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x1b2/0x283 lib/dump_stack.c:58
kasan_report_error.cold+0x144/0x194 mm/kasan/report.c:349
kasan_report+0x6f/0x7b mm/kasan/report.c:409
memcpy+0x35/0x50 mm/kasan/kasan.c:303
memcpy include/linux/string.h:372 [inline]
build_sit_entries fs/f2fs/segment.c:3289 [inline]
build_segment_manager+0x4fd2/0x7f40 fs/f2fs/segment.c:3564
f2fs_fill_super+0x2e21/0x56a0 fs/f2fs/super.c:2581
mount_bdev+0x2b3/0x360 fs/super.c:1134
mount_fs+0x92/0x2a0 fs/super.c:1237
vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046
vfs_kern_mount fs/namespace.c:1036 [inline]
do_new_mount fs/namespace.c:2549 [inline]
do_mount+0xe53/0x2a00 fs/namespace.c:2879
SYSC_mount fs/namespace.c:3095 [inline]
SyS_mount+0xa8/0x120 fs/namespace.c:3072
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x4608fa
RSP: 002b:00007f6cc404fa88 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f6cc404fb20 RCX: 00000000004608fa
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f6cc404fae0
RBP: 00007f6cc404fae0 R08: 00007f6cc404fb20 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000020000000
R13: 0000000020000100 R14: 0000000020000200 R15: 0000000020015000
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.