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SMTP id 5614622812f47-4f52b0a52abmr7307253b6e.60.1791144279804; Sun, 04 Oct 2026 13:04:39 -0700 (PDT) Date: Sun, 04 Oct 2026 13:04:39 -0700 In-Reply-To: <20261004-scev-minimal-rebase-v2-0-f6254e29fdf2@gmail.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6ac2b157.01314a6c.556a8.000a.GAE@google.com> Subject: [syzbot ci] Re: bpf: use scalar evolution to widen bounded loops From: syzbot ci To: andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, emil@etsalapatis.com, ezingerman@fb.com, kernel-team@fb.com, yonghong.song@linux.dev Cc: syzbot@lists.linux.dev, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" syzbot ci has tested the following series [v2] bpf: use scalar evolution to widen bounded loops https://lore.kernel.org/all/20261004-scev-minimal-rebase-v2-0-f6254e29fdf2@gmail.com * [PATCH bpf-next v2 01/43] bpf: represent stack access effects with arg_access_info * [PATCH bpf-next v2 02/43] bpf: describe helper stack accesses with arg_access_info * [PATCH bpf-next v2 03/43] bpf: describe kfunc stack accesses with arg_access_info * [PATCH bpf-next v2 04/43] bpf: track may_write flags in liveness * [PATCH bpf-next v2 05/43] bpf: summarize may write stack slots in insn_aux_data * [PATCH bpf-next v2 06/43] bpf: summarize live stack slots in insn_aux_data * [PATCH bpf-next v2 07/43] bpf: summarize regs that may hold a frame pointer in insn_aux_data * [PATCH bpf-next v2 08/43] bpf: record write effects for atomic operations in liveness.c * [PATCH bpf-next v2 09/43] bpf: add tnum_alignment() * [PATCH bpf-next v2 10/43] bpf: add cnum{32,64}_union() * [PATCH bpf-next v2 11/43] bpf: add cnum64_intersect_linear() * [PATCH bpf-next v2 12/43] bpf: expose comparison opcode transformations * [PATCH bpf-next v2 13/43] bpf: allow subrange relations for PTR_TO_STACK in regsafe() * [PATCH bpf-next v2 14/43] bpf: representation for intervals with steps * [PATCH bpf-next v2 15/43] bpf: varying offset access support for PTR_TO_BTF_ID pointers * [PATCH bpf-next v2 16/43] bpf: save DFS postorder numbers for program instructions * [PATCH bpf-next v2 17/43] bpf: move the live-register and SCC printout to a standalone function * [PATCH bpf-next v2 18/43] bpf: compute immediate dominators * [PATCH bpf-next v2 19/43] bpf: compute loop hierarchy * [PATCH bpf-next v2 20/43] bpf: add bpf_set_reg_range() * [PATCH bpf-next v2 21/43] bpf: add bpf_mark_reg_known_scalar() * [PATCH bpf-next v2 22/43] bpf: add bpf_reg_union() * [PATCH bpf-next v2 23/43] bpf: add a min-heap for ordered analysis worklists * [PATCH bpf-next v2 24/43] bpf: record basic-block ends in insn_aux_data * [PATCH bpf-next v2 25/43] bpf: add bpf_split_cur_state() * [PATCH bpf-next v2 26/43] bpf: add bpf_same_memory_origin() * [PATCH bpf-next v2 27/43] bpf: allow precision backtracking between overlapping checkpoints * [PATCH bpf-next v2 28/43] bpf: compute scalar evolution expressions for loops * [PATCH bpf-next v2 29/43] bpf: use SCEV to widen bounded loops * [PATCH bpf-next v2 30/43] bpf: avoid widening registers that hinder exact stack-slot tracking * [PATCH bpf-next v2 31/43] bpf: bpf_func_state size optimization * [PATCH bpf-next v2 32/43] selftests/bpf: __msg_next tag for matching messages on consecutive lines * [PATCH bpf-next v2 33/43] selftests/bpf: bound UNIX socket path loops by sun_path size * [PATCH bpf-next v2 34/43] selftests/bpf: test for stack-pointer subrange pruning * [PATCH bpf-next v2 35/43] selftests/bpf: tests for may_write stack-liveness tracking * [PATCH bpf-next v2 36/43] selftests/bpf: tests for may_def marks of atomic RMW operations * [PATCH bpf-next v2 37/43] selftests/bpf: tests for map special cases in bpf_helper_stack_access_bytes() * [PATCH bpf-next v2 38/43] selftests/bpf: tests for register base/step arithmetic * [PATCH bpf-next v2 39/43] selftests/bpf: tests for register base/step state pruning * [PATCH bpf-next v2 40/43] selftests/bpf: tests for varying offset access to PTR_TO_BTF_ID * [PATCH bpf-next v2 41/43] selftests/bpf: tests for loop hierarchy computation * [PATCH bpf-next v2 42/43] selftests/bpf: tests for immediate dominator computation * [PATCH bpf-next v2 43/43] selftests/bpf: tests for SCEV analysis and loop widening and found the following issue: general protection fault in bpf_compute_scev Full report is available here: https://ci.syzbot.org/series/ff81cb40-7952-4f8a-b785-1f9e875f9b1f *** general protection fault in bpf_compute_scev tree: bpf-next URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/bpf/bpf-next.git base: 99dc1ba542420db6b8df209744f55cc52466ad91 arch: amd64 compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 config: https://ci.syzbot.org/builds/a6050598-290a-4e4f-bba8-55721490a3a8/config syz repro: https://ci.syzbot.org/findings/63885d0d-bef7-464a-9e39-0d57d15cba85/syz_repro Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 0 UID: 0 PID: 5853 Comm: syz.1.18 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:compute_insn_scevs kernel/bpf/scev.c:1489 [inline] RIP: 0010:bpf_compute_scev+0x5482/0x6050 kernel/bpf/scev.c:1569 Code: 24 08 30 04 00 00 49 81 c7 30 04 00 00 45 31 ed 48 8b 44 24 10 4e 8d 34 a8 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <0f> b6 04 08 84 c0 0f 85 af 00 00 00 41 8b 16 48 89 df 31 f6 48 8b RSP: 0018:ffffc9000372f6e0 EFLAGS: 00010247 RAX: 0000000000000000 RBX: ffff8881144bad00 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: 0000000000000011 RDI: 0000000000000011 RBP: ffffc9000372f910 R08: ffff888101bd0000 R09: 0000000000000004 R10: 000000000000010f R11: 0000000000000000 R12: 0000000000000011 R13: 0000000000000000 R14: 0000000000000004 R15: 0000000000000430 FS: 00007fd0dc1f56c0(0000) GS:ffff88818d6b6000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fd0db270050 CR3: 00000001bf29a000 CR4: 00000000000006f0 Call Trace: bpf_check+0x2fbe/0x3550 kernel/bpf/verifier.c:23332 bpf_prog_load+0x1594/0x1d60 kernel/bpf/syscall.c:3177 __sys_bpf+0xd86/0xe00 kernel/bpf/syscall.c:6437 __do_sys_bpf kernel/bpf/syscall.c:6559 [inline] __se_sys_bpf kernel/bpf/syscall.c:6556 [inline] __x64_sys_bpf+0xba/0xd0 kernel/bpf/syscall.c:6556 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fd0db39e159 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fd0dc1f5028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 00007fd0db625fa0 RCX: 00007fd0db39e159 RDX: 0000000000000094 RSI: 0000200000000040 RDI: 0000000000000005 RBP: 00007fd0db43506b R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fd0db626038 R14: 00007fd0db625fa0 R15: 00007fff2dcab378 Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:compute_insn_scevs kernel/bpf/scev.c:1489 [inline] RIP: 0010:bpf_compute_scev+0x5482/0x6050 kernel/bpf/scev.c:1569 Code: 24 08 30 04 00 00 49 81 c7 30 04 00 00 45 31 ed 48 8b 44 24 10 4e 8d 34 a8 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <0f> b6 04 08 84 c0 0f 85 af 00 00 00 41 8b 16 48 89 df 31 f6 48 8b RSP: 0018:ffffc9000372f6e0 EFLAGS: 00010247 RAX: 0000000000000000 RBX: ffff8881144bad00 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: 0000000000000011 RDI: 0000000000000011 RBP: ffffc9000372f910 R08: ffff888101bd0000 R09: 0000000000000004 R10: 000000000000010f R11: 0000000000000000 R12: 0000000000000011 R13: 0000000000000000 R14: 0000000000000004 R15: 0000000000000430 FS: 00007fd0dc1f56c0(0000) GS:ffff88818d6b6000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fd0db270050 CR3: 00000001bf29a000 CR4: 00000000000006f0 ---------------- Code disassembly (best guess), 4 bytes skipped: 0: 00 00 add %al,(%rax) 2: 49 81 c7 30 04 00 00 add $0x430,%r15 9: 45 31 ed xor %r13d,%r13d c: 48 8b 44 24 10 mov 0x10(%rsp),%rax 11: 4e 8d 34 a8 lea (%rax,%r13,4),%r14 15: 4c 89 f0 mov %r14,%rax 18: 48 c1 e8 03 shr $0x3,%rax 1c: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx 23: fc ff df * 26: 0f b6 04 08 movzbl (%rax,%rcx,1),%eax <-- trapping instruction 2a: 84 c0 test %al,%al 2c: 0f 85 af 00 00 00 jne 0xe1 32: 41 8b 16 mov (%r14),%edx 35: 48 89 df mov %rbx,%rdi 38: 31 f6 xor %esi,%esi 3a: 48 rex.W 3b: 8b .byte 0x8b *** If these findings have caused you to resend the series or submit a separate fix, please add the following tag to your commit message: Tested-by: syzbot@syzkaller.appspotmail.com --- This report is generated by a bot. It may contain errors. syzbot ci engineers can be reached at syzkaller@googlegroups.com. To test a fix for this bug, please reply with `#syz test` (on a separate line) and attach the patch to the email. Notes: - The patch will be applied on top of the tested series (as an incremental fix). - To test a new version of the whole series, please send it directly to syzbot@lists.linux.dev. - Arguments like custom git repos and branches are not supported.