[syzbot] [nvme?] KASAN: slab-use-after-free Read in nvmf_free_options

[syzbot] [nvme?] KASAN: slab-use-after-free Read in nvmf_free_options

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    0d8395707651 Merge tag 'soc-fixes-7.2-2' of git://git.kern..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=130897b9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c05be6c9b0d36cb9
dashboard link: https://syzkaller.appspot.com/bug?extid=f58e57380a6083c4041d
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 (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-0d839570.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f71d0db84455/vmlinux-0d839570.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9e4025aaafe2/bzImage-0d839570.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f58e57380a6083c4041d@syzkaller.appspotmail.com

FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 1
CPU: 0 UID: 0 PID: 5326 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 fail_dump lib/fault-inject.c:73 [inline]
 should_fail_ex+0x40c/0x560 lib/fault-inject.c:174
 should_failslab+0xa8/0x100 mm/failslab.c:46
 slab_pre_alloc_hook mm/slub.c:4539 [inline]
 slab_alloc_node mm/slub.c:4897 [inline]
 __do_kmalloc_node mm/slub.c:5333 [inline]
 __kmalloc_node_track_caller_noprof+0x100/0x730 mm/slub.c:5471
 kvasprintf+0xeb/0x1a0 lib/kasprintf.c:25
 kobject_set_name_vargs+0x61/0x110 lib/kobject.c:274
 dev_set_name+0xe2/0x140 drivers/base/core.c:3560
 nvme_add_ctrl+0x6e/0x270 drivers/nvme/host/core.c:5248
 nvme_fc_init_ctrl+0xcb0/0x1450 drivers/nvme/host/fc.c:3554
 nvme_fc_create_ctrl+0x4cd/0x520 drivers/nvme/host/fc.c:3723
 nvmf_create_ctrl drivers/nvme/host/fabrics.c:1359 [inline]
 nvmf_dev_write+0x24ca/0x2d90 drivers/nvme/host/fabrics.c:1406
 vfs_write+0x296/0xba0 fs/read_write.c:685
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fea9b39e0d9
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:00007fea9c299fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fea9b625fa0 RCX: 00007fea9b39e0d9
RDX: 000000000000007e RSI: 0000200000000a00 RDI: 0000000000000005
RBP: 00007fea9c29a050 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 00007fea9b626038 R14: 00007fea9b625fa0 R15: 00007ffe156ed1b8
 </TASK>
==================================================================
BUG: KASAN: slab-use-after-free in nvmf_free_options+0x30/0x190 drivers/nvme/host/fabrics.c:1284
Read of size 8 at addr ffff88801f4a2550 by task syz.0.0/5326

CPU: 0 UID: 0 PID: 5326 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
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+0x117/0x150 mm/kasan/report.c:595
 nvmf_free_options+0x30/0x190 drivers/nvme/host/fabrics.c:1284
 nvmf_create_ctrl drivers/nvme/host/fabrics.c:1374 [inline]
 nvmf_dev_write+0x267f/0x2d90 drivers/nvme/host/fabrics.c:1406
 vfs_write+0x296/0xba0 fs/read_write.c:685
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fea9b39e0d9
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:00007fea9c299fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fea9b625fa0 RCX: 00007fea9b39e0d9
RDX: 000000000000007e RSI: 0000200000000a00 RDI: 0000000000000005
RBP: 00007fea9c29a050 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 00007fea9b626038 R14: 00007fea9b625fa0 R15: 00007ffe156ed1b8
 </TASK>

Allocated by task 5326:
 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]
 __kmalloc_cache_noprof+0x32d/0x660 mm/slub.c:5489
 _kmalloc_noprof include/linux/slab.h:988 [inline]
 _kzalloc_noprof include/linux/slab.h:1309 [inline]
 nvmf_create_ctrl drivers/nvme/host/fabrics.c:1315 [inline]
 nvmf_dev_write+0x243/0x2d90 drivers/nvme/host/fabrics.c:1406
 vfs_write+0x296/0xba0 fs/read_write.c:685
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5326:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2677 [inline]
 slab_free mm/slub.c:6377 [inline]
 kfree+0x1c5/0x640 mm/slub.c:6692
 nvme_fc_ctrl_free drivers/nvme/host/fc.c:2374 [inline]
 kref_put include/linux/kref.h:65 [inline]
 nvme_fc_ctrl_put+0x2cc/0x340 drivers/nvme/host/fc.c:2381
 nvme_free_ctrl+0x38c/0x570 drivers/nvme/host/core.c:5146
 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+0x222/0x550 lib/kobject.c:737
 nvme_put_ctrl drivers/nvme/host/nvme.h:833 [inline]
 nvme_fc_init_ctrl+0xe17/0x1450 drivers/nvme/host/fc.c:3605
 nvme_fc_create_ctrl+0x4cd/0x520 drivers/nvme/host/fc.c:3723
 nvmf_create_ctrl drivers/nvme/host/fabrics.c:1359 [inline]
 nvmf_dev_write+0x24ca/0x2d90 drivers/nvme/host/fabrics.c:1406
 vfs_write+0x296/0xba0 fs/read_write.c:685
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88801f4a2500
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 80 bytes inside of
 freed 192-byte region [ffff88801f4a2500, ffff88801f4a25c0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1f4a2
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801b0413c0 dead000000000122 0000000000000000
raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5289, tgid 5289 (syz-executor), ts 83703979346, free_ts 83087386547
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1859
 prep_new_page mm/page_alloc.c:1867 [inline]
 get_page_from_freelist+0x21fa/0x2270 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5304
 alloc_slab_page mm/slub.c:3266 [inline]
 allocate_slab+0x79/0x5e0 mm/slub.c:3380
 new_slab mm/slub.c:3426 [inline]
 refill_objects+0x2d5/0x350 mm/slub.c:7310
 refill_sheaf mm/slub.c:2804 [inline]
 __pcs_replace_empty_main+0x2bf/0x6b0 mm/slub.c:4675
 alloc_from_pcs mm/slub.c:4773 [inline]
 slab_alloc_node mm/slub.c:4905 [inline]
 __do_kmalloc_node mm/slub.c:5333 [inline]
 __kmalloc_node_track_caller_noprof+0x557/0x730 mm/slub.c:5471
 kmemdup_noprof+0x2b/0x70 mm/util.c:138
 kmemdup_noprof include/linux/fortify-string.h:715 [inline]
 ebt_register_table+0x18e/0x1190 net/bridge/netfilter/ebtables.c:1197
 find_inlist_lock_noload+0x171/0x260 net/bridge/netfilter/ebtables.c:344
 find_inlist_lock net/bridge/netfilter/ebtables.c:372 [inline]
 find_table_lock net/bridge/netfilter/ebtables.c:380 [inline]
 do_ebt_get_ctl+0x367/0x1f30 net/bridge/netfilter/ebtables.c:2512
 nf_getsockopt+0x26e/0x290 net/netfilter/nf_sockopt.c:116
 ip_getsockopt+0x19e/0x230 net/ipv4/ip_sockglue.c:1777
 do_sock_getsockopt+0x569/0xa70 net/socket.c:2474
 __sys_getsockopt net/socket.c:2505 [inline]
 __do_sys_getsockopt net/socket.c:2512 [inline]
 __se_sys_getsockopt net/socket.c:2509 [inline]
 __x64_sys_getsockopt+0x1a4/0x240 net/socket.c:2509
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
page last free pid 75 tgid 75 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1406 [inline]
 free_unref_folios+0xd84/0x14a0 mm/page_alloc.c:3011
 shrink_folio_list+0x4b16/0x5330 mm/vmscan.c:1582
 evict_folios+0x3821/0x49e0 mm/vmscan.c:4834
 try_to_shrink_lruvec+0xb4f/0xed0 mm/vmscan.c:4983
 shrink_one+0x233/0x730 mm/vmscan.c:5024
 shrink_many mm/vmscan.c:5087 [inline]
 lru_gen_shrink_node mm/vmscan.c:5165 [inline]
 shrink_node+0x3303/0x3b60 mm/vmscan.c:6154
 kswapd_shrink_node mm/vmscan.c:7008 [inline]
 balance_pgdat mm/vmscan.c:7186 [inline]
 kswapd+0x17b6/0x31c0 mm/vmscan.c:7462
 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

Memory state around the buggy address:
 ffff88801f4a2400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801f4a2480: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff88801f4a2500: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                 ^
 ffff88801f4a2580: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff88801f4a2600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


---
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[PATCH] nvme-fc: fix double free of fabrics options when nvme_add_ctrl() fails

[Rihyeon Kim]

nvmf_create_ctrl() frees opts when ->create_ctrl() returns an error, so
a transport must not free it on its own error paths.  nvme_fc_ctrl_free()
therefore only calls nvmf_free_options() while ctrl->ctrl.opts is still
set, and nvme_fc_init_ctrl() clears that pointer before its last put.

It only does so on the fail_ctrl: path, though.  When nvme_add_ctrl()
fails, nvme_fc_init_ctrl() jumps to out_put_ctrl: instead, so
nvme_fc_ctrl_free() still sees ctrl->ctrl.opts set and frees opts, and
nvmf_create_ctrl() frees it again.

Reproduced with nvme-fcloop and failslab by failing the kvasprintf() in
dev_set_name(), called from nvme_add_ctrl():

  BUG: KASAN: slab-use-after-free in nvmf_free_options+0x30/0x190
   nvmf_free_options+0x30/0x190 drivers/nvme/host/fabrics.c:1284
   nvmf_create_ctrl drivers/nvme/host/fabrics.c:1374 [inline]
  Freed by task 5534:
   nvme_fc_ctrl_free drivers/nvme/host/fc.c:2374 [inline]
   nvme_fc_init_ctrl+0xe17/0x1450 drivers/nvme/host/fc.c:3605

Without KASAN opts is simply freed twice.

nvme-tcp and nvme-rdma reach the same error path, but their free_ctrl
only frees opts once the controller is on the global list, so they are
not affected.

Clear ctrl->ctrl.opts on the out_put_ctrl: path as well.  The same
injection then returns -EIO without a report.

Fixes: 1a9e218195a5 ("nvme: split device add from initialization")
Cc: stable@vger.kernel.org
Reported-by: syzbot+f58e57380a6083c4041d@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=f58e57380a6083c4041d
Assisted-by: Claude:claude-opus-5
Signed-off-by: Rihyeon Kim <rihyeon8648@gmail.com>
---
 drivers/nvme/host/fc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index 04363b9c4489..e4d0eeccd846 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -3601,6 +3601,9 @@ nvme_fc_init_ctrl(struct device *dev, struct nvmf_ctrl_options *opts,
 	nvme_uninit_ctrl(&ctrl->ctrl);
 
 out_put_ctrl:
+	/* nvme_add_ctrl() failures skip the clear in fail_ctrl: above */
+	ctrl->ctrl.opts = NULL;
+
 	/* Remove core ctrl ref. */
 	nvme_put_ctrl(&ctrl->ctrl);
 

base-commit: 0ce37745d4bfbc493f718169c3974898ffec8ee7
-- 
2.43.0

Re: [PATCH] nvme-fc: fix double free of fabrics options when nvme_add_ctrl() fails

[Niklas Cassel]

On Tue, Aug 11, 2026 at 09:53:10PM +0900, Rihyeon Kim wrote:

(snip)

> diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
> index 04363b9c4489..e4d0eeccd846 100644
> --- a/drivers/nvme/host/fc.c
> +++ b/drivers/nvme/host/fc.c
> @@ -3601,6 +3601,9 @@ nvme_fc_init_ctrl(struct device *dev, struct nvmf_ctrl_options *opts,
>  	nvme_uninit_ctrl(&ctrl->ctrl);
>  
>  out_put_ctrl:
> +	/* nvme_add_ctrl() failures skip the clear in fail_ctrl: above */
> +	ctrl->ctrl.opts = NULL;
> +
>  	/* Remove core ctrl ref. */
>  	nvme_put_ctrl(&ctrl->ctrl);
>  
> 
> base-commit: 0ce37745d4bfbc493f718169c3974898ffec8ee7
> -- 
> 2.43.0
> 
> 

Wouldn't a nicer fix be to change nvme_fc_ctrl_free() to look more like
nvme_tcp_ctrl_free(), i.e. something like:

diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index 04363b9c4489..2b4c222995ea 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -2359,19 +2359,22 @@ nvme_fc_ctrl_free(struct kref *ref)
                container_of(ref, struct nvme_fc_ctrl, ref);
        unsigned long flags;

+       if (list_empty(&ctrl->ctrl_list))
+               goto free_ctrl;
+
        /* remove from rport list */
        spin_lock_irqsave(&ctrl->rport->lock, flags);
        list_del(&ctrl->ctrl_list);
        spin_unlock_irqrestore(&ctrl->rport->lock, flags);

-       kfree(ctrl->queues);
-
        put_device(ctrl->dev);
        nvme_fc_rport_put(ctrl->rport);

        ida_free(&nvme_fc_ctrl_cnt, ctrl->cnum);
-       if (ctrl->ctrl.opts)
-               nvmf_free_options(ctrl->ctrl.opts);
+
+       nvmf_free_options(ctrl->ctrl.opts);
+free_ctrl:
+       kfree(ctrl->queues);
        kfree(ctrl);
 }

@@ -3593,8 +3596,6 @@ nvme_fc_init_ctrl(struct device *dev, struct nvmf_ctrl_options *opts,
        cancel_work_sync(&ctrl->ctrl.reset_work);
        cancel_delayed_work_sync(&ctrl->connect_work);

-       ctrl->ctrl.opts = NULL;
-
        if (ctrl->ctrl.admin_tagset)
                nvme_remove_admin_tag_set(&ctrl->ctrl);
        /* initiate nvme ctrl ref counting teardown */



However, I'm not familar with the fc driver, so this suggestion is untested.


Kind regards,
Niklas

Re: [PATCH] nvme-fc: fix double free of fabrics options when nvme_add_ctrl() fails

[Keith Busch]

On Tue, Aug 11, 2026 at 09:53:10PM +0900, Rihyeon Kim wrote:
> It only does so on the fail_ctrl: path, though.  When nvme_add_ctrl()
> fails, nvme_fc_init_ctrl() jumps to out_put_ctrl: instead, so
> nvme_fc_ctrl_free() still sees ctrl->ctrl.opts set and frees opts, and
> nvmf_create_ctrl() frees it again.

...

> diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
> index 04363b9c4489..e4d0eeccd846 100644
> --- a/drivers/nvme/host/fc.c
> +++ b/drivers/nvme/host/fc.c
> @@ -3601,6 +3601,9 @@ nvme_fc_init_ctrl(struct device *dev, struct nvmf_ctrl_options *opts,
>  	nvme_uninit_ctrl(&ctrl->ctrl);
>  
>  out_put_ctrl:
> +	/* nvme_add_ctrl() failures skip the clear in fail_ctrl: above */
> +	ctrl->ctrl.opts = NULL;
> +
>  	/* Remove core ctrl ref. */
>  	nvme_put_ctrl(&ctrl->ctrl);

Can't you move the setting from the "fail_ctrl:" label to the
"out_put_ctrl:" one instead of duplicating it for both?