[v5.15] possible deadlock in ib_get_eth_speed

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 674f684f7c61 Linux 5.15.212
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13e7c49e580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f161cbc9aef65db0
dashboard link: https://syzkaller.appspot.com/bug?extid=d614ebac44c180b31682
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/f55be2937b89/disk-674f684f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a19fb0ffc049/vmlinux-674f684f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/365d4529a007/bzImage-674f684f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d614eb...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.4.40/4375 is trying to acquire lock:
ffffffff8d44d488 (rtnl_mutex){+.+.}-{3:3}, at: ib_get_eth_speed+0x16b/0x500 drivers/infiniband/core/verbs.c:1905

but task is already holding lock:
ffff888063491218 (&rxe->usdev_lock){+.+.}-{3:3}, at: rxe_query_port+0x46/0x190 drivers/infiniband/sw/rxe/rxe_verbs.c:40

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&rxe->usdev_lock){+.+.}-{3:3}:
__mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
rxe_query_port+0x46/0x190 drivers/infiniband/sw/rxe/rxe_verbs.c:40
__ib_query_port drivers/infiniband/core/device.c:2081 [inline]
ib_query_port+0x15e/0x7e0 drivers/infiniband/core/device.c:2113
rxe_port_immutable+0xe0/0x240 drivers/infiniband/sw/rxe/rxe_verbs.c:132
setup_port_data drivers/infiniband/core/device.c:857 [inline]
setup_device drivers/infiniband/core/device.c:1253 [inline]
ib_register_device+0xd42/0x12e0 drivers/infiniband/core/device.c:1392
rxe_register_device+0x256/0x360 drivers/infiniband/sw/rxe/rxe_verbs.c:1137
rxe_net_add+0x77/0xe0 drivers/infiniband/sw/rxe/rxe_net.c:549
rxe_param_set_add+0x395/0x590 drivers/infiniband/sw/rxe/rxe_sysfs.c:68
param_attr_store+0x20a/0x300 kernel/params.c:585
module_attr_store+0x5b/0x80 kernel/params.c:905
kernfs_fop_write_iter+0x3a8/0x500 fs/kernfs/file.c:296
call_write_iter include/linux/fs.h:2173 [inline]
new_sync_write fs/read_write.c:507 [inline]
vfs_write+0x748/0xd70 fs/read_write.c:594
ksys_write+0x153/0x260 fs/read_write.c:647
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #1 (param_lock){+.+.}-{3:3}:
__mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
ieee80211_rate_control_ops_get net/mac80211/rate.c:192 [inline]
rate_control_alloc net/mac80211/rate.c:239 [inline]
ieee80211_init_rate_ctrl_alg+0x171/0x5e0 net/mac80211/rate.c:983
ieee80211_register_hw+0x23c6/0x3a60 net/mac80211/main.c:1252
mac80211_hwsim_new_radio+0x209d/0x4050 drivers/net/wireless/mac80211_hwsim.c:3373
init_mac80211_hwsim+0x581/0x720 drivers/net/wireless/mac80211_hwsim.c:4606
do_one_initcall+0x272/0x730 init/main.c:1315
do_initcall_level+0x13d/0x1f0 init/main.c:1388
do_initcalls+0x4b/0x90 init/main.c:1404
kernel_init_freeable+0x3d5/0x560 init/main.c:1628
kernel_init+0x19/0x1b0 init/main.c:1519
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #0 (rtnl_mutex){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain kernel/locking/lockdep.c:3788 [inline]
__lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012
lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
__mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
ib_get_eth_speed+0x16b/0x500 drivers/infiniband/core/verbs.c:1905
rxe_query_port+0x58/0x190 drivers/infiniband/sw/rxe/rxe_verbs.c:41
__ib_query_port drivers/infiniband/core/device.c:2081 [inline]
ib_query_port+0x15e/0x7e0 drivers/infiniband/core/device.c:2113
rxe_port_immutable+0xe0/0x240 drivers/infiniband/sw/rxe/rxe_verbs.c:132
setup_port_data drivers/infiniband/core/device.c:857 [inline]
setup_device drivers/infiniband/core/device.c:1253 [inline]
ib_register_device+0xd42/0x12e0 drivers/infiniband/core/device.c:1392
rxe_register_device+0x256/0x360 drivers/infiniband/sw/rxe/rxe_verbs.c:1137
rxe_net_add+0x77/0xe0 drivers/infiniband/sw/rxe/rxe_net.c:549
rxe_param_set_add+0x395/0x590 drivers/infiniband/sw/rxe/rxe_sysfs.c:68
param_attr_store+0x20a/0x300 kernel/params.c:585
module_attr_store+0x5b/0x80 kernel/params.c:905
kernfs_fop_write_iter+0x3a8/0x500 fs/kernfs/file.c:296
call_write_iter include/linux/fs.h:2173 [inline]
new_sync_write fs/read_write.c:507 [inline]
vfs_write+0x748/0xd70 fs/read_write.c:594
ksys_write+0x153/0x260 fs/read_write.c:647
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0

other info that might help us debug this:

Chain exists of:
rtnl_mutex --> param_lock --> &rxe->usdev_lock

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&rxe->usdev_lock);
lock(param_lock);
lock(&rxe->usdev_lock);
lock(rtnl_mutex);

*** DEADLOCK ***

6 locks held by syz.4.40/4375:
#0: ffff88802ce3a870 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2bf/0x370 fs/file.c:1056
#1: ffff8880791d8460 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x296/0xd70 fs/read_write.c:590
#2: ffff888062e3ac88 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1dc/0x500 fs/kernfs/file.c:287
#3: ffff888019d96578 (kn->active){++++}-{0:0}, at: kernfs_fop_write_iter+0x1fd/0x500 fs/kernfs/file.c:288
#4: ffffffff8c1d4a08 (param_lock){+.+.}-{3:3}, at: kernel_param_lock kernel/params.c:598 [inline]
#4: ffffffff8c1d4a08 (param_lock){+.+.}-{3:3}, at: param_attr_store+0xcb/0x300 kernel/params.c:583
#5: ffff888063491218 (&rxe->usdev_lock){+.+.}-{3:3}, at: rxe_query_port+0x46/0x190 drivers/infiniband/sw/rxe/rxe_verbs.c:40

stack backtrace:
CPU: 1 PID: 4375 Comm: syz.4.40 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
<TASK>
dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2133
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain kernel/locking/lockdep.c:3788 [inline]
__lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012
lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
__mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
ib_get_eth_speed+0x16b/0x500 drivers/infiniband/core/verbs.c:1905
rxe_query_port+0x58/0x190 drivers/infiniband/sw/rxe/rxe_verbs.c:41
__ib_query_port drivers/infiniband/core/device.c:2081 [inline]
ib_query_port+0x15e/0x7e0 drivers/infiniband/core/device.c:2113
rxe_port_immutable+0xe0/0x240 drivers/infiniband/sw/rxe/rxe_verbs.c:132
setup_port_data drivers/infiniband/core/device.c:857 [inline]
setup_device drivers/infiniband/core/device.c:1253 [inline]
ib_register_device+0xd42/0x12e0 drivers/infiniband/core/device.c:1392
rxe_register_device+0x256/0x360 drivers/infiniband/sw/rxe/rxe_verbs.c:1137
rxe_net_add+0x77/0xe0 drivers/infiniband/sw/rxe/rxe_net.c:549
rxe_param_set_add+0x395/0x590 drivers/infiniband/sw/rxe/rxe_sysfs.c:68
param_attr_store+0x20a/0x300 kernel/params.c:585
module_attr_store+0x5b/0x80 kernel/params.c:905
kernfs_fop_write_iter+0x3a8/0x500 fs/kernfs/file.c:296
call_write_iter include/linux/fs.h:2173 [inline]
new_sync_write fs/read_write.c:507 [inline]
vfs_write+0x748/0xd70 fs/read_write.c:594
ksys_write+0x153/0x260 fs/read_write.c:647
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f61574d9e99
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:00007f6155732028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f6157761fa0 RCX: 00007f61574d9e99
RDX: 0000000000000005 RSI: 0000200000000080 RDI: 0000000000000003
RBP: 00007f615756feaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6157762038 R14: 00007f6157761fa0 R15: 00007ffd155bd788
</TASK>
eth0 speed is unknown, defaulting to 1000
eth0 speed is unknown, defaulting to 1000
eth0 speed is unknown, defaulting to 1000
infiniband rxe0: set active
infiniband rxe0: added eth0
infiniband rxe0: Couldn't open port 1
RDS/IB: rxe0: added
smc: adding ib device rxe0 with port count 1
smc: ib device rxe0 port 1 has pnetid
eth0 speed is unknown, defaulting to 1000


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 674f684f7c61 Linux 5.15.212
git tree: linux-5.15.y

console output: https://syzkaller.appspot.com/x/log.txt?x=136ed1b9580000

kernel config: https://syzkaller.appspot.com/x/.config?x=f161cbc9aef65db0
dashboard link: https://syzkaller.appspot.com/bug?extid=d614ebac44c180b31682
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=170cd9b9580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1745b1b9580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f55be2937b89/disk-674f684f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a19fb0ffc049/vmlinux-674f684f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/365d4529a007/bzImage-674f684f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d614eb...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------

syz.0.17/4343 is trying to acquire lock:

ffffffff8d44d488 (rtnl_mutex){+.+.}-{3:3}, at: ib_get_eth_speed+0x16b/0x500 drivers/infiniband/core/verbs.c:1905

but task is already holding lock:

ffff88807e1ad218 (&rxe->usdev_lock){+.+.}-{3:3}, at: rxe_query_port+0x46/0x190 drivers/infiniband/sw/rxe/rxe_verbs.c:40

5 locks held by syz.0.17/4343:
#0: ffff888074aa0460 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x296/0xd70 fs/read_write.c:590
#1: ffff88802b373088 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1dc/0x500 fs/kernfs/file.c:287
#2: ffff888143b8c1d8 (kn->active){++++}-{0:0}, at: kernfs_fop_write_iter+0x1fd/0x500 fs/kernfs/file.c:288
#3: ffffffff8c1d4a08 (param_lock){+.+.}-{3:3}, at: kernel_param_lock kernel/params.c:598 [inline]
#3: ffffffff8c1d4a08 (param_lock){+.+.}-{3:3}, at: param_attr_store+0xcb/0x300 kernel/params.c:583
#4: ffff88807e1ad218 (&rxe->usdev_lock){+.+.}-{3:3}, at: rxe_query_port+0x46/0x190 drivers/infiniband/sw/rxe/rxe_verbs.c:40

stack backtrace:
CPU: 1 PID: 4343 Comm: syz.0.17 Not tainted syzkaller #0

RIP: 0033:0x7fcce2664f99

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:00007ffd7f8fc9a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fcce28ecfa0 RCX: 00007fcce2664f99

RDX: 0000000000000005 RSI: 0000200000000080 RDI: 0000000000000003

RBP: 00007fcce26fbec4 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 00007fcce28ecfac R14: 00007fcce28ecfa0 R15: 00007fcce28ecfa0

</TASK>
eth0 speed is unknown, defaulting to 1000
eth0 speed is unknown, defaulting to 1000
eth0 speed is unknown, defaulting to 1000
infiniband rxe0: set active
infiniband rxe0: added eth0

RDS/IB: rxe0: added
smc: adding ib device rxe0 with port count 1
smc: ib device rxe0 port 1 has pnetid
eth0 speed is unknown, defaulting to 1000


---

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