On Mon, Apr 22, 2024 at 4:21 PM syzbot <syzbot+0c4150bff9fff3bf023c@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: 4ac828960a60 Merge branch 'eee-linkmode-bitmaps' > git tree: net-next > console+strace: https://syzkaller.appspot.com/x/log.txt?x=14710a54180000 > kernel config: https://syzkaller.appspot.com/x/.config?x=57c41f64f37f51c5 > dashboard link: https://syzkaller.appspot.com/bug?extid=0c4150bff9fff3bf023c > 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=17cc49d8180000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12c88616180000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/f1bd74942969/disk-4ac82896.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/c99cbac61b8b/vmlinux-4ac82896.xz > kernel image: https://storage.googleapis.com/syzbot-assets/fa3d589c2a1c/bzImage-4ac82896.xz > > The issue was bisected to: > > commit 219eee9c0d16f1b754a8b85275854ab17df0850a > Author: Florian Westphal <fw@xxxxxxxxx> > Date: Fri Feb 16 11:36:57 2024 +0000 > > net: skbuff: add overflow debug check to pull/push helpers > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=166b3a4c180000 > final oops: https://syzkaller.appspot.com/x/report.txt?x=156b3a4c180000 > console output: https://syzkaller.appspot.com/x/log.txt?x=116b3a4c180000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+0c4150bff9fff3bf023c@xxxxxxxxxxxxxxxxxxxxxxxxx > Fixes: 219eee9c0d16 ("net: skbuff: add overflow debug check to pull/push helpers") > > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 5074 at include/linux/skbuff.h:2723 pskb_may_pull_reason include/linux/skbuff.h:2723 [inline] > WARNING: CPU: 1 PID: 5074 at include/linux/skbuff.h:2723 pskb_may_pull include/linux/skbuff.h:2739 [inline] > WARNING: CPU: 1 PID: 5074 at include/linux/skbuff.h:2723 skb_ensure_writable+0x2ef/0x440 net/core/skbuff.c:6103 > Modules linked in: > CPU: 1 PID: 5074 Comm: syz-executor365 Not tainted 6.8.0-rc5-syzkaller-01654-g4ac828960a60 #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024 > RIP: 0010:pskb_may_pull_reason include/linux/skbuff.h:2723 [inline] > RIP: 0010:pskb_may_pull include/linux/skbuff.h:2739 [inline] > RIP: 0010:skb_ensure_writable+0x2ef/0x440 net/core/skbuff.c:6103 > Code: e8 b6 f7 57 f8 4c 89 ef 31 f6 31 d2 b9 20 08 00 00 48 83 c4 28 5b 41 5c 41 5d 41 5e 41 5f 5d e9 17 04 fe ff e8 92 f7 57 f8 90 <0f> 0b 90 e9 3e fd ff ff 44 89 f7 44 89 e6 e8 3e f9 57 f8 45 39 e6 > RSP: 0018:ffffc900039ef8f8 EFLAGS: 00010293 > RAX: ffffffff893b75de RBX: ffff88802c8a1000 RCX: ffff88802a155940 > RDX: 0000000000000000 RSI: 00000000fb6014e4 RDI: 0000000000000000 > RBP: 00000000fb6014e4 R08: ffffffff893b7317 R09: 1ffffffff1f0bcb5 > R10: dffffc0000000000 R11: ffffffffa0000954 R12: 00000000fb6014e4 > R13: ffff88802c8a1000 R14: ffffc90000b06030 R15: dffffc0000000000 > FS: 0000555556fa9380(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000001b7b398 CR3: 00000000241e8000 CR4: 00000000003506f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > <TASK> > __bpf_try_make_writable net/core/filter.c:1665 [inline] > bpf_try_make_writable net/core/filter.c:1671 [inline] > ____bpf_skb_pull_data net/core/filter.c:1862 [inline] > bpf_skb_pull_data+0x7c/0x230 net/core/filter.c:1851 > bpf_prog_ca74b6b79e086095+0x1d/0x1f > bpf_dispatcher_nop_func include/linux/bpf.h:1235 [inline] > __bpf_prog_run include/linux/filter.h:651 [inline] > bpf_prog_run include/linux/filter.h:658 [inline] > bpf_test_run+0x408/0x900 net/bpf/test_run.c:423 > bpf_prog_test_run_skb+0xaf9/0x13a0 net/bpf/test_run.c:1056 > bpf_prog_test_run+0x33a/0x3b0 kernel/bpf/syscall.c:4188 > __sys_bpf+0x48d/0x810 kernel/bpf/syscall.c:5591 > __do_sys_bpf kernel/bpf/syscall.c:5680 [inline] > __se_sys_bpf kernel/bpf/syscall.c:5678 [inline] > __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5678 > do_syscall_64+0xf9/0x240 > entry_SYSCALL_64_after_hwframe+0x6f/0x77 > RIP: 0033:0x7f6a0471c4a9 > Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007ffcdcead7e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 > RAX: ffffffffffffffda RBX: 00007ffcdcead9b8 RCX: 00007f6a0471c4a9 > RDX: 0000000000000050 RSI: 0000000020000080 RDI: 000000000000000a > RBP: 00007f6a0478f610 R08: 0000000000000000 R09: 00007ffcdcead9b8 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 > R13: 00007ffcdcead9a8 R14: 0000000000000001 R15: 0000000000000001 > </TASK> > > > --- > 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@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > For information about bisection process see: https://goo.gl/tpsmEJ#bisection > > If the report is already addressed, let syzbot know by replying with: > #syz fix: exact-commit-title > > If you want syzbot to run the reproducer, reply with: > #syz test: git://repo/address.git branch-or-commit-hash > If you attach or paste a git patch, syzbot will apply it before testing. > > 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 Hmm... Not sure how to deal with this one... this is a 'false positive' diff --git a/net/core/filter.c b/net/core/filter.c index 58e8e1a70aa752a2c045117e00d8797478da4738..a7cea6d717ef321215bc4cf9ab3b83535c4eec98 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -1662,6 +1662,11 @@ static DEFINE_PER_CPU(struct bpf_scratchpad, bpf_sp); static inline int __bpf_try_make_writable(struct sk_buff *skb, unsigned int write_len) { +#if defined(CONFIG_DEBUG_NET) + /* Avoid a splat in pskb_may_pull_reason() */ + if (write_len > INT_MAX) + return -EINVAL; +#endif return skb_ensure_writable(skb, write_len); }
