linux-kernel - [syzbot] [bpf?] KMSAN: uninit-value in trie_delete

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Date: Tue, 26 Mar 2024 12:00:23 -0700
From: syzbot <syzbot+603bcd9b0bf1d94dbb9b@...kaller.appspotmail.com>
To: andrii@...nel.org, ast@...nel.org, bpf@...r.kernel.org, 
	daniel@...earbox.net, eddyz87@...il.com, haoluo@...gle.com, 
	john.fastabend@...il.com, jolsa@...nel.org, kpsingh@...nel.org, 
	linux-kernel@...r.kernel.org, martin.lau@...ux.dev, sdf@...gle.com, 
	song@...nel.org, syzkaller-bugs@...glegroups.com, yonghong.song@...ux.dev
Subject: [syzbot] [bpf?] KMSAN: uninit-value in trie_delete_elem

Hello,

syzbot found the following issue on:

HEAD commit:    4f55aa85a874 Merge tag 'fbdev-for-6.9-rc1' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11a8dc6e180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e6bd769cb793b98a
dashboard link: https://syzkaller.appspot.com/bug?extid=603bcd9b0bf1d94dbb9b
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/991fcbce770a/disk-4f55aa85.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/bd716e5d2c3c/vmlinux-4f55aa85.xz
kernel image: https://storage.googleapis.com/syzbot-assets/bf1151dbf5fc/bzImage-4f55aa85.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+603bcd9b0bf1d94dbb9b@...kaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in trie_delete_elem+0xc0/0xbe0 kernel/bpf/lpm_trie.c:448
 trie_delete_elem+0xc0/0xbe0 kernel/bpf/lpm_trie.c:448
 ____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_run128+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_run3+0x132/0x320 kernel/trace/bpf_trace.c:2421
 __bpf_trace_kmem_cache_free+0x31/0x40 include/trace/events/kmem.h:114
 trace_kmem_cache_free include/trace/events/kmem.h:114 [inline]
 kmem_cache_free+0x6da/0xa80 mm/slub.c:4343
 mt_free_one lib/maple_tree.c:172 [inline]
 mas_destroy+0x56c9/0x5cd0 lib/maple_tree.c:5612
 mas_store_prealloc+0x39c/0x550 lib/maple_tree.c:5487
 vma_iter_store mm/internal.h:1290 [inline]
 vma_complete+0x9b0/0x14e0 mm/mmap.c:535
 __split_vma+0x1037/0x1200 mm/mmap.c:2385
 split_vma mm/mmap.c:2411 [inline]
 vma_modify+0x37c/0x4c0 mm/mmap.c:2452
 vma_modify_flags include/linux/mm.h:3303 [inline]
 mprotect_fixup+0x790/0x1170 mm/mprotect.c:635
 do_mprotect_pkey+0x1159/0x1850 mm/mprotect.c:809
 __do_sys_mprotect mm/mprotect.c:830 [inline]
 __se_sys_mprotect mm/mprotect.c:827 [inline]
 __ia32_sys_mprotect+0x98/0xf0 mm/mprotect.c:827
 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
 __do_fast_syscall_32+0xba/0x120 arch/x86/entry/common.c:321
 do_fast_syscall_32+0x38/0x80 arch/x86/entry/common.c:346
 do_SYSENTER_32+0x1f/0x30 arch/x86/entry/common.c:384
 entry_SYSENTER_compat_after_hwframe+0x7a/0x84

Local variable stack created at:
 __bpf_prog_run128+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_run3+0x132/0x320 kernel/trace/bpf_trace.c:2421

CPU: 0 PID: 14388 Comm: syz-executor.4 Not tainted 6.8.0-syzkaller-13006-g4f55aa85a874 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
=====================================================


---
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