[syzbot] [v9fs?] WARNING: refcount bug in p9_req_put (4)
syzbot <[email protected]> Sat, 06 Jun 2026 04:35:28 -0700
| Newsgroups | dev.linux.lists.v9fs,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <[email protected]> |
Hello, syzbot found the following issue on: HEAD commit: ba3e43a9e601 Merge tag 'soc-fixes-7.1-2' of git://git.kern.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=12b65a86580000 kernel config: https://syzkaller.appspot.com/x/.config?x=8118209836970b54 dashboard link: https://syzkaller.appspot.com/bug?extid=f6fdb3bdd2c1d419e263 compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=158b5f2e580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13d47dd2580000 Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-ba3e43a9.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/12db9228338c/vmlinux-ba3e43a9.xz kernel image: https://storage.googleapis.com/syzbot-assets/c8dfb3210b18/bzImage-ba3e43a9.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: [email protected] 9pnet: Tag 0 still in use ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xf4/0x130 lib/refcount.c:28, CPU#2: syz-executor/5869 Modules linked in: CPU: 2 UID: 0 PID: 5869 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:refcount_warn_saturate+0xf4/0x130 lib/refcount.c:28 Code: cc e8 b0 53 0f fd 48 8d 3d 89 44 e8 0b 67 48 0f b9 3a e8 9f 53 0f fd 5b 5d e9 d8 4f 93 06 e8 93 53 0f fd 48 8d 3d 7c 44 e8 0b <67> 48 0f b9 3a e8 82 53 0f fd 5b 5d c3 cc cc cc cc e8 76 53 0f fd RSP: 0018:ffffc900060a7c38 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffff88803ecb7218 RCX: ffffffff84f95c3b RDX: ffff88802b710000 RSI: ffffffff84f95ccd RDI: ffffffff90e1a150 RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000004 R10: 0000000000000003 R11: 0000000000000000 R12: ffff88803ecb7218 R13: ffff888035c59800 R14: ffffc900060a7cc8 R15: ffff88801fa88040 FS: 000055557717e500(0000) GS:ffff8880d6583000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055e3b8556be0 CR3: 0000000037a35000 CR4: 0000000000352ef0 Call Trace: <TASK> __refcount_sub_and_test include/linux/refcount.h:400 [inline] __refcount_dec_and_test include/linux/refcount.h:432 [inline] refcount_dec_and_test include/linux/refcount.h:450 [inline] p9_req_put+0x1ec/0x250 net/9p/client.c:281 p9_tag_cleanup net/9p/client.c:308 [inline] p9_client_destroy.cold+0x20/0xe9 net/9p/client.c:963 v9fs_session_close+0x49/0x2d0 fs/9p/v9fs.c:543 v9fs_kill_super+0x4d/0xa0 fs/9p/vfs_super.c:175 deactivate_locked_super+0xc1/0x1b0 fs/super.c:476 deactivate_super fs/super.c:509 [inline] deactivate_super+0xe7/0x110 fs/super.c:505 cleanup_mnt+0x21f/0x450 fs/namespace.c:1312 task_work_run+0x150/0x240 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:67 [inline] exit_to_user_mode_loop+0x157/0x670 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline] do_syscall_64+0x666/0x870 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fbad779e097 Code: a2 c7 05 5c 06 25 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8 RSP: 002b:00007fffe847bc88 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 00007fbad78321ca RCX: 00007fbad779e097 RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fffe847bd40 RBP: 00007fffe847bd40 R08: 00007fffe847cd40 R09: 00000000ffffffff R10: 0000000000000000 R11: 0000000000000246 R12: 00007fffe847cdd0 R13: 00007fbad78321ca R14: 000000000004828a R15: 00007fffe847ce10 </TASK> ---------------- Code disassembly (best guess): 0: cc int3 1: e8 b0 53 0f fd call 0xfd0f53b6 6: 48 8d 3d 89 44 e8 0b lea 0xbe84489(%rip),%rdi # 0xbe84496 d: 67 48 0f b9 3a ud1 (%edx),%rdi 12: e8 9f 53 0f fd call 0xfd0f53b6 17: 5b pop %rbx 18: 5d pop %rbp 19: e9 d8 4f 93 06 jmp 0x6934ff6 1e: e8 93 53 0f fd call 0xfd0f53b6 23: 48 8d 3d 7c 44 e8 0b lea 0xbe8447c(%rip),%rdi # 0xbe844a6 * 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2f: e8 82 53 0f fd call 0xfd0f53b6 34: 5b pop %rbx 35: 5d pop %rbp 36: c3 ret 37: cc int3 38: cc int3 39: cc int3 3a: cc int3 3b: e8 76 53 0f fd call 0xfd0f53b6 --- This report is generated by a bot. 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