[syzbot ci] Re: bpf: Fix unintended eviction when updating lru hash maps

[syzbot ci]

syzbot ci has tested the following series

[v1] bpf: Fix unintended eviction when updating lru hash maps
https://lore.kernel.org/all/20251202153032.1...@linux.dev
* [PATCH bpf-next 1/3] bpf: Avoid unintended eviction when updating lru_hash maps
* [PATCH bpf-next 2/3] bpf: Avoid unintended eviction when updating lru_percpu_hash maps
* [PATCH bpf-next 3/3] selftests/bpf: Add tests to verify no unintended eviction when updating lru hash maps

and found the following issue:
general protection fault in bpf_lru_push_free

Full report is available here:
https://ci.syzbot.org/series/64db9547-852d-4c56-a3a1-3d18f254330c

***

general protection fault in bpf_lru_push_free

tree: bpf-next
URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/bpf/bpf-next.git
base: 5262cb23393f7e86a64d1a45eeaa8a6f99f03d10
arch: amd64
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
config: https://ci.syzbot.org/builds/702a7a8c-4385-4089-a777-8b47155f8794/config
C repro: https://ci.syzbot.org/findings/0cffd810-925f-42f4-88d2-8d21195f341e/c_repro
syz repro: https://ci.syzbot.org/findings/0cffd810-925f-42f4-88d2-8d21195f341e/syz_repro

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000004: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]
CPU: 0 UID: 0 PID: 5953 Comm: syz.0.17 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:bpf_percpu_lru_push_free kernel/bpf/bpf_lru_list.c:539 [inline]
RIP: 0010:bpf_lru_push_free+0x6e/0xbb0 kernel/bpf/bpf_lru_list.c:551
Code: 01 0f 85 e4 00 00 00 4c 89 f0 48 c1 e8 03 80 3c 28 00 74 08 4c 89 f7 e8 c0 82 42 00 4d 8b 3e 4c 8d 73 10 4c 89 f0 48 c1 e8 03 <0f> b6 04 28 84 c0 0f 85 5b 09 00 00 45 0f b7 36 bf 08 00 00 00 44
RSP: 0018:ffffc900046d7b48 EFLAGS: 00010202
RAX: 0000000000000004 RBX: 0000000000000010 RCX: ffff888112941d00
RDX: 0000000000000000 RSI: 0000000000000010 RDI: ffff888117c02300
RBP: dffffc0000000000 R08: ffffffff8f7cee77 R09: 1ffffffff1ef9dce
R10: dffffc0000000000 R11: fffffbfff1ef9dcf R12: 0000000000000002
R13: 00000000fffffffe R14: 0000000000000020 R15: 0000607d55cf6a80
FS: 000055555edc7500(0000) GS:ffff88818eb38000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2ed63fff CR3: 000000010bca0000 CR4: 00000000000006f0
Call Trace:
<TASK>
htab_lru_push_free kernel/bpf/hashtab.c:1183 [inline]
htab_lru_map_update_elem+0x33e/0xa90 kernel/bpf/hashtab.c:1266
bpf_map_update_value+0x751/0x920 kernel/bpf/syscall.c:294
map_update_elem+0x355/0x4b0 kernel/bpf/syscall.c:1817
__sys_bpf+0x619/0x860 kernel/bpf/syscall.c:6150
__do_sys_bpf kernel/bpf/syscall.c:6272 [inline]
__se_sys_bpf kernel/bpf/syscall.c:6270 [inline]
__x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6270
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe41118f7c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffcd4179988 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007fe4113e5fa0 RCX: 00007fe41118f7c9
RDX: 0000000000000020 RSI: 0000200000000800 RDI: 0000000000000002
RBP: 00007fe4111f297f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe4113e5fa0 R14: 00007fe4113e5fa0 R15: 0000000000000003
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:bpf_percpu_lru_push_free kernel/bpf/bpf_lru_list.c:539 [inline]
RIP: 0010:bpf_lru_push_free+0x6e/0xbb0 kernel/bpf/bpf_lru_list.c:551
Code: 01 0f 85 e4 00 00 00 4c 89 f0 48 c1 e8 03 80 3c 28 00 74 08 4c 89 f7 e8 c0 82 42 00 4d 8b 3e 4c 8d 73 10 4c 89 f0 48 c1 e8 03 <0f> b6 04 28 84 c0 0f 85 5b 09 00 00 45 0f b7 36 bf 08 00 00 00 44
RSP: 0018:ffffc900046d7b48 EFLAGS: 00010202
RAX: 0000000000000004 RBX: 0000000000000010 RCX: ffff888112941d00
RDX: 0000000000000000 RSI: 0000000000000010 RDI: ffff888117c02300
RBP: dffffc0000000000 R08: ffffffff8f7cee77 R09: 1ffffffff1ef9dce
R10: dffffc0000000000 R11: fffffbfff1ef9dcf R12: 0000000000000002
R13: 00000000fffffffe R14: 0000000000000020 R15: 0000607d55cf6a80
FS: 000055555edc7500(0000) GS:ffff88818eb38000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2ed63fff CR3: 000000010bca0000 CR4: 00000000000006f0
----------------
Code disassembly (best guess):
0: 01 0f add %ecx,(%rdi)
2: 85 e4 test %esp,%esp
4: 00 00 add %al,(%rax)
6: 00 4c 89 f0 add %cl,-0x10(%rcx,%rcx,4)
a: 48 c1 e8 03 shr $0x3,%rax
e: 80 3c 28 00 cmpb $0x0,(%rax,%rbp,1)
12: 74 08 je 0x1c
14: 4c 89 f7 mov %r14,%rdi
17: e8 c0 82 42 00 call 0x4282dc
1c: 4d 8b 3e mov (%r14),%r15
1f: 4c 8d 73 10 lea 0x10(%rbx),%r14
23: 4c 89 f0 mov %r14,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 0f b6 04 28 movzbl (%rax,%rbp,1),%eax <-- trapping instruction
2e: 84 c0 test %al,%al
30: 0f 85 5b 09 00 00 jne 0x991
36: 45 0f b7 36 movzwl (%r14),%r14d
3a: bf 08 00 00 00 mov $0x8,%edi
3f: 44 rex.R


***

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: syz...@syzkaller.appspotmail.com

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