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

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Message-ID: <0000000000004cf0fe06160c8d71@google.com>
Date: Sun, 14 Apr 2024 04:10:26 -0700
From: syzbot <syzbot+0a079d6ef3831217a230@...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 htab_percpu_map_lookup_elem

Hello,

syzbot found the following issue on:

HEAD commit:    2c71fdf02a95 Merge tag 'drm-fixes-2024-04-09' of https://g..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=170425a1180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b5bc506ebba90cbf
dashboard link: https://syzkaller.appspot.com/bug?extid=0a079d6ef3831217a230
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=16abe213180000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16ab97ad180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/36c01edd4b1e/disk-2c71fdf0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7df598a3dceb/vmlinux-2c71fdf0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/678bacfb883c/bzImage-2c71fdf0.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0a079d6ef3831217a230@...kaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in __htab_map_lookup_elem kernel/bpf/hashtab.c:691 [inline]
BUG: KMSAN: uninit-value in htab_percpu_map_lookup_elem+0x3eb/0x4f0 kernel/bpf/hashtab.c:2302
 __htab_map_lookup_elem kernel/bpf/hashtab.c:691 [inline]
 htab_percpu_map_lookup_elem+0x3eb/0x4f0 kernel/bpf/hashtab.c:2302
 ____bpf_map_lookup_elem kernel/bpf/helpers.c:42 [inline]
 bpf_map_lookup_elem+0x5c/0x80 kernel/bpf/helpers.c:38
 ___bpf_prog_run+0x13fe/0xe0f0 kernel/bpf/core.c:1997
 __bpf_prog_run32+0xb2/0xe0 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_run4+0x150/0x340 kernel/trace/bpf_trace.c:2422
 __bpf_trace_mm_page_alloc+0x37/0x50 include/trace/events/kmem.h:177
 trace_mm_page_alloc include/trace/events/kmem.h:177 [inline]
 __alloc_pages+0xdc0/0xe70 mm/page_alloc.c:4597
 alloc_pages_mpol+0x299/0x990 mm/mempolicy.c:2264
 vma_alloc_folio+0x418/0x680 mm/mempolicy.c:2303
 wp_page_copy mm/memory.c:3263 [inline]
 do_wp_page+0x196c/0x66e0 mm/memory.c:3660
 handle_pte_fault mm/memory.c:5316 [inline]
 __handle_mm_fault mm/memory.c:5441 [inline]
 handle_mm_fault+0x5b76/0xce00 mm/memory.c:5606
 do_user_addr_fault arch/x86/mm/fault.c:1362 [inline]
 handle_page_fault arch/x86/mm/fault.c:1505 [inline]
 exc_page_fault+0x419/0x730 arch/x86/mm/fault.c:1563
 asm_exc_page_fault+0x2b/0x30 arch/x86/include/asm/idtentry.h:623

Local variable stack created at:
 __bpf_prog_run32+0x43/0xe0 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_run4+0x150/0x340 kernel/trace/bpf_trace.c:2422

CPU: 0 PID: 5021 Comm: syz-executor180 Not tainted 6.9.0-rc3-syzkaller-00023-g2c71fdf02a95 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
=====================================================


---
This report is generated by a bot. It may contain errors.
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