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Precedence: bulk X-Mailing-List: linux-ext4@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: syzbot writes: > Hello, > > syzbot found the following issue on: > > HEAD commit: 32b6ef9a5d0e Add linux-next specific files for G20260902 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=14b44125580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=32ceed1c94c11059 > dashboard link: https://syzkaller.appspot.com/bug?extid=5a7a23af225c215902e7 > compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/9a1f38fb6f24/disk-32b6ef9a.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/f3152eed43a4/vmlinux-32b6ef9a.xz > kernel image: https://storage.googleapis.com/syzbot-assets/e7fbd36e1b12/bzImage-32b6ef9a.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+5a7a23af225c215902e7@syzkaller.appspotmail.com > > Oops: general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] SMP KASAN PTI > KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] > CPU: 0 UID: 0 PID: 4945 Comm: jbd2/sda1-8 Not tainted syzkaller #0 PREEMPT(full) > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 > RIP: 0010:const_folio_flags include/linux/page-flags.h:345 [inline] > RIP: 0010:folio_test_dropbehind include/linux/page-flags.h:600 [inline] > RIP: 0010:__bh_submit+0x22d/0x8d0 fs/buffer.c:1109 > Code: c1 e8 03 48 89 44 24 18 42 80 3c 20 00 74 08 48 89 df e8 26 f6 d7 ff 48 89 5c 24 28 48 8b 1b 4c 8d 7b 08 4c 89 f8 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 ff e8 04 f6 d7 ff 4d 8b 3f 4c 89 fe 48 > RSP: 0018:ffffc9001016f868 EFLAGS: 00010202 > RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff84b96ff9 > RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffff888075a7a660 > RBP: 0000000000009801 R08: ffff888075a7a6bf R09: 1ffff1100eb4f4d7 > R10: dffffc0000000000 R11: ffffed100eb4f4d8 R12: dffffc0000000000 > R13: ffff888075a7a640 R14: ffff8880123a17e0 R15: 0000000000000008 > FS: 0000000000000000(0000) GS:ffff888124ccb000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007fe1ee627da0 CR3: 0000000074fa8000 CR4: 00000000003526f0 > Call Trace: > > jbd2_journal_commit_transaction+0x22a9/0x5cd0 fs/jbd2/commit.c:751 > kjournald2+0x3bc/0x750 fs/jbd2/journal.c:200 > kthread+0x38b/0x480 kernel/kthread.c:436 > ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 > > Modules linked in: > ---[ end trace 0000000000000000 ]--- > RIP: 0010:const_folio_flags include/linux/page-flags.h:345 [inline] > RIP: 0010:folio_test_dropbehind include/linux/page-flags.h:600 [inline] > RIP: 0010:__bh_submit+0x22d/0x8d0 fs/buffer.c:1109 > Code: c1 e8 03 48 89 44 24 18 42 80 3c 20 00 74 08 48 89 df e8 26 f6 d7 ff 48 89 5c 24 28 48 8b 1b 4c 8d 7b 08 4c 89 f8 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 ff e8 04 f6 d7 ff 4d 8b 3f 4c 89 fe 48 > RSP: 0018:ffffc9001016f868 EFLAGS: 00010202 > RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff84b96ff9 > RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffff888075a7a660 > RBP: 0000000000009801 R08: ffff888075a7a6bf R09: 1ffff1100eb4f4d7 > R10: dffffc0000000000 R11: ffffed100eb4f4d8 R12: dffffc0000000000 > R13: ffff888075a7a640 R14: ffff8880123a17e0 R15: 0000000000000008 > FS: 0000000000000000(0000) GS:ffff888124dcb000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007f87c696cf80 CR3: 000000000eb48000 CR4: 00000000003526f0 > ---------------- > Code disassembly (best guess): > 0: c1 e8 03 shr $0x3,%eax > 3: 48 89 44 24 18 mov %rax,0x18(%rsp) > 8: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1) > d: 74 08 je 0x17 > f: 48 89 df mov %rbx,%rdi > 12: e8 26 f6 d7 ff call 0xffd7f63d > 17: 48 89 5c 24 28 mov %rbx,0x28(%rsp) > 1c: 48 8b 1b mov (%rbx),%rbx > 1f: 4c 8d 7b 08 lea 0x8(%rbx),%r15 > 23: 4c 89 f8 mov %r15,%rax > 26: 48 c1 e8 03 shr $0x3,%rax > * 2a: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1) <-- trapping instruction > 2f: 74 08 je 0x39 > 31: 4c 89 ff mov %r15,%rdi > 34: e8 04 f6 d7 ff call 0xffd7f63d > 39: 4d 8b 3f mov (%r15),%r15 > 3c: 4c 89 fe mov %r15,%rsi > 3f: 48 rex.W > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > If the report is already addressed, let syzbot know by replying with: > #syz fix: exact-commit-title > > If you want to overwrite report's subsystems, reply with: > #syz set subsystems: new-subsystem > (See the list of subsystem names on the web dashboard) > > If the report is a duplicate of another one, reply with: > #syz dup: exact-subject-of-another-report > > If you want to undo deduplication, reply with: > #syz undup #syz test diff --git a/fs/buffer.c b/fs/buffer.c index 427d8a817cd5..f46fa6413032 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -1106,7 +1106,8 @@ static void __bh_submit(struct buffer_head *bh, blk_opf_t opf, bio = bio_alloc(bh->b_bdev, 1, opf, GFP_NOIO); - if (folio_test_dropbehind(bh->b_folio) && op_is_write(opf)) + if (bh->b_folio && folio_test_dropbehind(bh->b_folio) && + op_is_write(opf)) bio_set_flag(bio, BIO_COMPLETE_IN_TASK); if (IS_ENABLED(CONFIG_FS_ENCRYPTION))