[v6.6] WARNING in rt_cache_route

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: aa0e49877a2e Linux 6.6.148
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16b98cc6580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f0bc3d90c30838b5
dashboard link: https://syzkaller.appspot.com/bug?extid=f18641599de00253d395
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f83b390cfc1f/disk-aa0e4987.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1d4bdb338edd/vmlinux-aa0e4987.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3f57c1d51ee3/bzImage-aa0e4987.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f18641...@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 0 PID: 6265 at kernel/softirq.c:386 __local_bh_enable_ip+0x186/0x1c0 kernel/softirq.c:-1
Modules linked in:
CPU: 0 PID: 6265 Comm: krxrpcio/20000 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__local_bh_enable_ip+0x186/0x1c0 kernel/softirq.c:386
Code: 48 8b 04 25 28 00 00 00 48 3b 44 24 48 75 4e 48 8d 65 e0 5b 41 5c 41 5e 41 5f 5d c3 0f 0b e9 f3 fe ff ff e8 3c 00 00 00 eb a5 <0f> 0b e9 20 ff ff ff 48 c7 c1 ac af 8c 8e 80 e1 07 80 c1 03 38 c1
RSP: 0000:ffffc900033676e0 EFLAGS: 00010046
RAX: 0000000000000000 RBX: 0000000000000201 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000201 RDI: ffffffff8901575f
RBP: ffffc90003367760 R08: ffff8880b8e3dc83 R09: 1ffff110171c7b90
R10: dffffc0000000000 R11: ffffed10171c7b91 R12: ffff88805ee00878
R13: ffff88805ee00870 R14: dffffc0000000000 R15: 1ffff9200066cedc
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd674ac2000 CR3: 000000006cd2b000 CR4: 00000000003506f0
Call Trace:
<TASK>
spin_unlock_bh include/linux/spinlock.h:396 [inline]
rt_add_uncached_list net/ipv4/route.c:1544 [inline]
rt_cache_route+0x21f/0x280 net/ipv4/route.c:1517
rt_set_nexthop+0x48b/0xa10 net/ipv4/route.c:1632
__mkroute_output net/ipv4/route.c:2652 [inline]
ip_route_output_key_hash_rcu+0x18c9/0x2350 net/ipv4/route.c:2848
ip_route_output_key_hash+0x1f3/0x330 net/ipv4/route.c:2677
__ip_route_output_key include/net/route.h:134 [inline]
ip_route_output_flow+0x2a/0x150 net/ipv4/route.c:2905
ip_route_output_ports include/net/route.h:171 [inline]
rxrpc_assess_MTU_size net/rxrpc/peer_object.c:167 [inline]
rxrpc_init_peer+0x2da/0x740 net/rxrpc/peer_object.c:243
rxrpc_new_incoming_peer+0x27a/0x590 net/rxrpc/peer_object.c:313
rxrpc_alloc_incoming_call net/rxrpc/call_accept.c:289 [inline]
rxrpc_new_incoming_call+0x62a/0x1450 net/rxrpc/call_accept.c:382
rxrpc_input_packet net/rxrpc/io_thread.c:279 [inline]
rxrpc_io_thread+0x1b3e/0x24b0 net/rxrpc/io_thread.c:462
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>


---
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If you want to undo deduplication, reply with:
#syz undup

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: aa0e49877a2e Linux 6.6.148
git tree: linux-6.6.y

console output: https://syzkaller.appspot.com/x/log.txt?x=164997b9580000

kernel config: https://syzkaller.appspot.com/x/.config?x=f0bc3d90c30838b5
dashboard link: https://syzkaller.appspot.com/bug?extid=f18641599de00253d395
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16f6729e580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f83b390cfc1f/disk-aa0e4987.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1d4bdb338edd/vmlinux-aa0e4987.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3f57c1d51ee3/bzImage-aa0e4987.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f18641...@syzkaller.appspotmail.com

------------[ cut here ]------------

WARNING: CPU: 0 PID: 5941 at kernel/softirq.c:386 __local_bh_enable_ip+0x186/0x1c0 kernel/softirq.c:-1
Modules linked in:
CPU: 0 PID: 5941 Comm: krxrpcio/8999 Not tainted syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__local_bh_enable_ip+0x186/0x1c0 kernel/softirq.c:386
Code: 48 8b 04 25 28 00 00 00 48 3b 44 24 48 75 4e 48 8d 65 e0 5b 41 5c 41 5e 41 5f 5d c3 0f 0b e9 f3 fe ff ff e8 3c 00 00 00 eb a5 <0f> 0b e9 20 ff ff ff 48 c7 c1 ac af 8c 8e 80 e1 07 80 c1 03 38 c1

RSP: 0018:ffffc9000347f6e0 EFLAGS: 00010046

RAX: 0000000000000000 RBX: 0000000000000201 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000201 RDI: ffffffff8901575f

RBP: ffffc9000347f760 R08: ffff8880b8e3dc83 R09: 1ffff110171c7b90
R10: dffffc0000000000 R11: ffffed10171c7b91 R12: ffff88805cffab78
R13: ffff88805cffab70 R14: dffffc0000000000 R15: 1ffff9200068fedc

FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 0000001b2cc24008 CR3: 0000000060666000 CR4: 00000000003506f0

Call Trace:
<TASK>
spin_unlock_bh include/linux/spinlock.h:396 [inline]
rt_add_uncached_list net/ipv4/route.c:1544 [inline]
rt_cache_route+0x21f/0x280 net/ipv4/route.c:1517
rt_set_nexthop+0x48b/0xa10 net/ipv4/route.c:1632
__mkroute_output net/ipv4/route.c:2652 [inline]
ip_route_output_key_hash_rcu+0x18c9/0x2350 net/ipv4/route.c:2848
ip_route_output_key_hash+0x1f3/0x330 net/ipv4/route.c:2677
__ip_route_output_key include/net/route.h:134 [inline]
ip_route_output_flow+0x2a/0x150 net/ipv4/route.c:2905
ip_route_output_ports include/net/route.h:171 [inline]
rxrpc_assess_MTU_size net/rxrpc/peer_object.c:167 [inline]
rxrpc_init_peer+0x2da/0x740 net/rxrpc/peer_object.c:243
rxrpc_new_incoming_peer+0x27a/0x590 net/rxrpc/peer_object.c:313
rxrpc_alloc_incoming_call net/rxrpc/call_accept.c:289 [inline]
rxrpc_new_incoming_call+0x62a/0x1450 net/rxrpc/call_accept.c:382
rxrpc_input_packet net/rxrpc/io_thread.c:279 [inline]
rxrpc_io_thread+0x1b3e/0x24b0 net/rxrpc/io_thread.c:462
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>


---

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.

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 6436c12a2ced Linux 6.6.150
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1449bfb9580000

kernel config: https://syzkaller.appspot.com/x/.config?x=f0bc3d90c30838b5
dashboard link: https://syzkaller.appspot.com/bug?extid=f18641599de00253d395
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1249bfb9580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=131f6132580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f01168de2d4b/disk-6436c12a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e63b80c9c349/vmlinux-6436c12a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9297ad58728c/bzImage-6436c12a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f18641...@syzkaller.appspotmail.com

------------[ cut here ]------------

WARNING: CPU: 0 PID: 5939 at kernel/softirq.c:386 __local_bh_enable_ip+0x186/0x1c0 kernel/softirq.c:-1
Modules linked in:
CPU: 0 PID: 5939 Comm: krxrpcio/20000 Not tainted syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__local_bh_enable_ip+0x186/0x1c0 kernel/softirq.c:386
Code: 48 8b 04 25 28 00 00 00 48 3b 44 24 48 75 4e 48 8d 65 e0 5b 41 5c 41 5e 41 5f 5d c3 0f 0b e9 f3 fe ff ff e8 3c 00 00 00 eb a5 <0f> 0b e9 20 ff ff ff 48 c7 c1 ac af 8c 8e 80 e1 07 80 c1 03 38 c1

RSP: 0018:ffffc900034876e0 EFLAGS: 00010046

RAX: 0000000000000000 RBX: 0000000000000201 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000201 RDI: ffffffff8901575f

RBP: ffffc90003487760 R08: ffff8880b8e3dc83 R09: 1ffff110171c7b90
R10: dffffc0000000000 R11: ffffed10171c7b91 R12: ffff88807797dc78
R13: ffff88807797dc70 R14: dffffc0000000000 R15: 1ffff92000690edc

FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 0000200000000000 CR3: 0000000074bcf000 CR4: 00000000003506f0

Call Trace:
<TASK>
spin_unlock_bh include/linux/spinlock.h:396 [inline]
rt_add_uncached_list net/ipv4/route.c:1544 [inline]
rt_cache_route+0x21f/0x280 net/ipv4/route.c:1517
rt_set_nexthop+0x48b/0xa10 net/ipv4/route.c:1632
__mkroute_output net/ipv4/route.c:2652 [inline]
ip_route_output_key_hash_rcu+0x18c9/0x2350 net/ipv4/route.c:2848
ip_route_output_key_hash+0x1f3/0x330 net/ipv4/route.c:2677
__ip_route_output_key include/net/route.h:134 [inline]
ip_route_output_flow+0x2a/0x150 net/ipv4/route.c:2905
ip_route_output_ports include/net/route.h:171 [inline]
rxrpc_assess_MTU_size net/rxrpc/peer_object.c:167 [inline]
rxrpc_init_peer+0x2da/0x740 net/rxrpc/peer_object.c:243
rxrpc_new_incoming_peer+0x27a/0x590 net/rxrpc/peer_object.c:313
rxrpc_alloc_incoming_call net/rxrpc/call_accept.c:289 [inline]
rxrpc_new_incoming_call+0x62a/0x1450 net/rxrpc/call_accept.c:382
rxrpc_input_packet net/rxrpc/io_thread.c:279 [inline]
rxrpc_io_thread+0x1b3e/0x24b0 net/rxrpc/io_thread.c:462
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>


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