[syzbot] [rdma?] KFENCE: invalid free in gid_table_release_one

[syzbot] [rdma?] KFENCE: invalid free in gid_table_release_one

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    36ece9697e89 Add linux-next specific files for 20260331
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1415f5da580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e5c508e55e8ef9a7
dashboard link: https://syzkaller.appspot.com/bug?extid=4334f9a250019c1b79b4
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/46de62fad824/disk-36ece969.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/88dd71e1e51a/vmlinux-36ece969.xz
kernel image: https://storage.googleapis.com/syzbot-assets/51e7e482e157/bzImage-36ece969.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4334f9a250019c1b79b4@syzkaller.appspotmail.com

smbdirect: ib_dev[syz2] removed
==================================================================
BUG: KFENCE: invalid free in release_gid_table drivers/infiniband/core/cache.c:804 [inline]
BUG: KFENCE: invalid free in gid_table_release_one+0x384/0x470 drivers/infiniband/core/cache.c:877

Invalid free of 0xffff88823bf88fd8 (in kfence-#195):
 release_gid_table drivers/infiniband/core/cache.c:804 [inline]
 gid_table_release_one+0x384/0x470 drivers/infiniband/core/cache.c:877
 ib_device_release+0xd2/0x1c0 drivers/infiniband/core/device.c:482
 device_release+0xc4/0x1f0 drivers/base/core.c:-1
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x228/0x560 lib/kobject.c:737
 process_one_work kernel/workqueue.c:3278 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3361
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3442
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

kfence-#195: 0xffff88823bf88f00-0xffff88823bf88fdf, size=224, cache=kmalloc-256

allocated by task 14262 on cpu 0 at 508.565598s (487.512186s ago):
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 alloc_gid_table drivers/infiniband/core/cache.c:773 [inline]
 _gid_table_setup_one drivers/infiniband/core/cache.c:888 [inline]
 gid_table_setup_one drivers/infiniband/core/cache.c:916 [inline]
 ib_cache_setup_one+0x198/0x570 drivers/infiniband/core/cache.c:1606
 ib_register_device+0xfbd/0x13e0 drivers/infiniband/core/device.c:1426
 siw_device_register drivers/infiniband/sw/siw/siw_main.c:71 [inline]
 siw_newlink+0x8fe/0xde0 drivers/infiniband/sw/siw/siw_main.c:430
 nldev_newlink+0x5bc/0x650 drivers/infiniband/core/nldev.c:1812
 rdma_nl_rcv_msg drivers/infiniband/core/netlink.c:-1 [inline]
 rdma_nl_rcv_skb drivers/infiniband/core/netlink.c:239 [inline]
 rdma_nl_rcv+0x6d1/0xa10 drivers/infiniband/core/netlink.c:259
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:786 [inline]
 __sock_sendmsg net/socket.c:801 [inline]
 ____sys_sendmsg+0x972/0x9f0 net/socket.c:2650
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2704
 __sys_sendmsg net/socket.c:2736 [inline]
 __do_sys_sendmsg net/socket.c:2741 [inline]
 __se_sys_sendmsg net/socket.c:2739 [inline]
 __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 0 UID: 0 PID: 57 Comm: kworker/u8:4 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: ib-unreg-wq ib_unregister_work
==================================================================


---
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Re: [syzbot] [rdma?] KFENCE: invalid free in gid_table_release_one

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    36ece9697e89 Add linux-next specific files for 20260331
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=10dc99f6580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e5c508e55e8ef9a7
dashboard link: https://syzkaller.appspot.com/bug?extid=4334f9a250019c1b79b4
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15ebf5da580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1253b3d6580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/46de62fad824/disk-36ece969.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/88dd71e1e51a/vmlinux-36ece969.xz
kernel image: https://storage.googleapis.com/syzbot-assets/51e7e482e157/bzImage-36ece969.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4334f9a250019c1b79b4@syzkaller.appspotmail.com

smbdirect: ib_dev[syz2] removed
==================================================================
BUG: KASAN: invalid-free in release_gid_table drivers/infiniband/core/cache.c:804 [inline]
BUG: KASAN: invalid-free in gid_table_release_one+0x384/0x470 drivers/infiniband/core/cache.c:877
Free of addr ffff88802bcdb6d8 by task kworker/u8:2/35

CPU: 1 UID: 0 PID: 35 Comm: kworker/u8:2 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: ib-unreg-wq ib_unregister_work
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report_invalid_free+0xea/0x110 mm/kasan/report.c:557
 check_slab_allocation mm/kasan/common.c:-1 [inline]
 __kasan_slab_pre_free+0x104/0x120 mm/kasan/common.c:261
 kasan_slab_pre_free include/linux/kasan.h:199 [inline]
 slab_free_hook mm/slub.c:2634 [inline]
 slab_free mm/slub.c:6242 [inline]
 kfree+0x173/0x640 mm/slub.c:6557
 release_gid_table drivers/infiniband/core/cache.c:804 [inline]
 gid_table_release_one+0x384/0x470 drivers/infiniband/core/cache.c:877
 ib_device_release+0xd2/0x1c0 drivers/infiniband/core/device.c:482
 device_release+0xc4/0x1f0 drivers/base/core.c:-1
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x228/0x560 lib/kobject.c:737
 process_one_work kernel/workqueue.c:3278 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3361
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3442
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 6021:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5292 [inline]
 __kmalloc_noprof+0x35c/0x760 mm/slub.c:5304
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 alloc_gid_table drivers/infiniband/core/cache.c:773 [inline]
 _gid_table_setup_one drivers/infiniband/core/cache.c:888 [inline]
 gid_table_setup_one drivers/infiniband/core/cache.c:916 [inline]
 ib_cache_setup_one+0x198/0x570 drivers/infiniband/core/cache.c:1606
 ib_register_device+0xfbd/0x13e0 drivers/infiniband/core/device.c:1426
 siw_device_register drivers/infiniband/sw/siw/siw_main.c:71 [inline]
 siw_newlink+0x8fe/0xde0 drivers/infiniband/sw/siw/siw_main.c:430
 nldev_newlink+0x5bc/0x650 drivers/infiniband/core/nldev.c:1812
 rdma_nl_rcv_msg drivers/infiniband/core/netlink.c:-1 [inline]
 rdma_nl_rcv_skb drivers/infiniband/core/netlink.c:239 [inline]
 rdma_nl_rcv+0x6d1/0xa10 drivers/infiniband/core/netlink.c:259
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:786 [inline]
 __sock_sendmsg net/socket.c:801 [inline]
 ____sys_sendmsg+0x972/0x9f0 net/socket.c:2650
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2704
 __sys_sendmsg net/socket.c:2736 [inline]
 __do_sys_sendmsg net/socket.c:2741 [inline]
 __se_sys_sendmsg net/socket.c:2739 [inline]
 __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88802bcdb600
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 216 bytes inside of
 224-byte region [ffff88802bcdb600, ffff88802bcdb6e0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2bcda
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88813fe38b40 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88813fe38b40 dead000000000100 dead000000000122
head: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
head: 00fff00000000001 ffffffffffffff81 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5953, tgid 5953 (syz-executor), ts 101457682506, free_ts 101330013904
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1858
 prep_new_page mm/page_alloc.c:1866 [inline]
 get_page_from_freelist+0x24ba/0x2540 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5226
 alloc_slab_page mm/slub.c:3278 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3467
 new_slab mm/slub.c:3525 [inline]
 refill_objects+0x339/0x3d0 mm/slub.c:7247
 refill_sheaf mm/slub.c:2816 [inline]
 __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4651
 alloc_from_pcs mm/slub.c:4749 [inline]
 slab_alloc_node mm/slub.c:4883 [inline]
 __kmalloc_cache_noprof+0x392/0x660 mm/slub.c:5407
 kmalloc_noprof include/linux/slab.h:950 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 ____ip_mc_inc_group+0x518/0xdd0 net/ipv4/igmp.c:1535
 __ip_mc_inc_group net/ipv4/igmp.c:1573 [inline]
 ip_mc_inc_group net/ipv4/igmp.c:1579 [inline]
 ip_mc_up+0x115/0x2e0 net/ipv4/igmp.c:1880
 inetdev_event+0xff6/0x1610 net/ipv4/devinet.c:1630
 notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2285 [inline]
 call_netdevice_notifiers net/core/dev.c:2299 [inline]
 __dev_notify_flags+0x1a9/0x310 net/core/dev.c:9835
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9864
 do_setlink+0xf82/0x4590 net/core/rtnetlink.c:3180
 rtnl_changelink net/core/rtnetlink.c:3798 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3957 [inline]
 rtnl_newlink+0x15a9/0x1be0 net/core/rtnetlink.c:4094
 rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6980
page last free pid 5953 tgid 5953 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1402 [inline]
 __free_frozen_pages+0xbc7/0xd30 mm/page_alloc.c:2943
 rcu_do_batch kernel/rcu/tree.c:2617 [inline]
 rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869
 handle_softirqs+0x22a/0x840 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0xca/0x220 kernel/softirq.c:735
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1061
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697

Memory state around the buggy address:
 ffff88802bcdb580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88802bcdb600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88802bcdb680: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
                                                    ^
 ffff88802bcdb700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88802bcdb780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


---
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.

Forwarded: [PATCH] RDMA/cache: fix invalid-free of flex-array data_vec in release_gid_table

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: [PATCH] RDMA/cache: fix invalid-free of flex-array data_vec in release_gid_table
Author: kartikey406@gmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master


Commit 74e2711bb2af ("RDMA/core: Use kzalloc_flex for GID table")
converted alloc_gid_table() to use kzalloc_flex(), which allocates
the ib_gid_table struct and its trailing data_vec flex array member
in a single contiguous slab block.

However, release_gid_table() was not updated accordingly and still
calls kfree(table->data_vec), passing a pointer that points 216 bytes
into the middle of the slab object rather than its head. This is an
invalid free which KASAN catches as:

  BUG: KASAN: invalid-free in release_gid_table+0x384/0x470

Since data_vec is now a flex array member of ib_gid_table, it is
freed implicitly when kfree(table) is called. Remove the redundant
and invalid kfree(table->data_vec).

Fixes: 74e2711bb2af ("RDMA/core: Use kzalloc_flex for GID table")
Reported-by: syzbot+4334f9a250019c1b79b4@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=4334f9a250019c1b79b4
Signed-off-by: Deepanshu <your@email.com>
---
 drivers/infiniband/core/cache.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/infiniband/core/cache.c b/drivers/infiniband/core/cache.c
index 896486fa6185..647a547e2d7f 100644
--- a/drivers/infiniband/core/cache.c
+++ b/drivers/infiniband/core/cache.c
@@ -801,7 +801,6 @@ static void release_gid_table(struct ib_device *device,
 	}
 
 	mutex_destroy(&table->lock);
-	kfree(table->data_vec);
 	kfree(table);
 }
 
-- 
2.43.0

Re: [syzbot] [rdma?] KFENCE: invalid free in gid_table_release_one

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+4334f9a250019c1b79b4@syzkaller.appspotmail.com
Tested-by: syzbot+4334f9a250019c1b79b4@syzkaller.appspotmail.com

Tested on:

commit:         36ece969 Add linux-next specific files for 20260331
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16e7a4d2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e5c508e55e8ef9a7
dashboard link: https://syzkaller.appspot.com/bug?extid=4334f9a250019c1b79b4
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=124c81ca580000

Note: testing is done by a robot and is best-effort only.