[syzbot] [bpf?] [net?] KMSAN: uninit-value in sock_map_delete_elem

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 70293240c5ce Merge tag 'timers-urgent-2024-03-23' of git:/..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=129e4dc9180000
kernel config: https://syzkaller.appspot.com/x/.config?x=e6bd769cb793b98a
dashboard link: https://syzkaller.appspot.com/bug?extid=eb02dc7f03dce0ef39f3
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13b5bbb9180000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14ee1291180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0de52742d0b8/disk-70293240.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f304697881bf/vmlinux-70293240.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2b9d8a9376f0/bzImage-70293240.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+eb02dc...@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in sock_map_delete_elem+0x15e/0x1c0 net/core/sock_map.c:442
sock_map_delete_elem+0x15e/0x1c0 net/core/sock_map.c:442
____bpf_map_delete_elem kernel/bpf/helpers.c:77 [inline]
bpf_map_delete_elem+0x5c/0x80 kernel/bpf/helpers.c:73
___bpf_prog_run+0x13fe/0xe0f0 kernel/bpf/core.c:1997
__bpf_prog_run160+0xb5/0xe0 kernel/bpf/core.c:2236
bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline]
__bpf_prog_run include/linux/filter.h:657 [inline]
bpf_prog_run include/linux/filter.h:664 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2381 [inline]
bpf_trace_run8+0x1bd/0x3a0 kernel/trace/bpf_trace.c:2426
__bpf_trace_jbd2_handle_stats+0x51/0x70 include/trace/events/jbd2.h:210
__traceiter_jbd2_handle_stats+0xc5/0x190 include/trace/events/jbd2.h:210
trace_jbd2_handle_stats include/trace/events/jbd2.h:210 [inline]
jbd2_journal_stop+0x1157/0x12c0 fs/jbd2/transaction.c:1869
__ext4_journal_stop+0x115/0x310 fs/ext4/ext4_jbd2.c:134
ext4_do_writepages+0x1c3c/0x62e0 fs/ext4/inode.c:2692
ext4_writepages+0x312/0x830 fs/ext4/inode.c:2768
do_writepages+0x427/0xc30 mm/page-writeback.c:2612
__writeback_single_inode+0x10d/0x12c0 fs/fs-writeback.c:1650
writeback_sb_inodes+0xb48/0x1be0 fs/fs-writeback.c:1941
__writeback_inodes_wb+0x14c/0x440 fs/fs-writeback.c:2012
wb_writeback+0x4da/0xdf0 fs/fs-writeback.c:2119
wb_check_old_data_flush fs/fs-writeback.c:2223 [inline]
wb_do_writeback fs/fs-writeback.c:2276 [inline]
wb_workfn+0x110c/0x1940 fs/fs-writeback.c:2304
process_one_work kernel/workqueue.c:3254 [inline]
process_scheduled_works+0xa81/0x1bd0 kernel/workqueue.c:3335
worker_thread+0xea5/0x1560 kernel/workqueue.c:3416
kthread+0x3e2/0x540 kernel/kthread.c:388
ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243

Local variable stack created at:
__bpf_prog_run160+0x45/0xe0 kernel/bpf/core.c:2236
bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline]
__bpf_prog_run include/linux/filter.h:657 [inline]
bpf_prog_run include/linux/filter.h:664 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2381 [inline]
bpf_trace_run8+0x1bd/0x3a0 kernel/trace/bpf_trace.c:2426

CPU: 0 PID: 33 Comm: kworker/u8:2 Not tainted 6.8.0-syzkaller-13213-g70293240c5ce #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
Workqueue: writeback wb_workfn (flush-8:0)
=====================================================


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