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* [syzbot] [bluetooth?] memory leak in init_srcu_struct_fields
@ 2026-05-30 20:57 syzbot
  2026-05-30 23:18 ` Forwarded: [PATCH] Bluetooth: hci_core: Fix SRCU leak when device is freed unregistered syzbot
                   ` (2 more replies)
  0 siblings, 3 replies; 10+ messages in thread
From: syzbot @ 2026-05-30 20:57 UTC (permalink / raw)
  To: linux-bluetooth, linux-kernel, luiz.dentz, marcel, syzkaller-bugs

Hello,

syzbot found the following issue on:

HEAD commit:    f377d0025eb0 Merge tag 'sh-for-v7.1-tag2' of git://git.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1737bb48580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9645c21cfd1d3e8f
dashboard link: https://syzkaller.appspot.com/bug?extid=535ecc844591e50588a5
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=164ed748580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10e6576c580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5d8163677f58/disk-f377d002.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cf2fcdb8200b/vmlinux-f377d002.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e9fb70799318/bzImage-f377d002.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+535ecc844591e50588a5@syzkaller.appspotmail.com

BUG: memory leak
unreferenced object 0xffff888111f49600 (size 512):
  comm "syz.0.17", pid 5937, jiffies 4294945495
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace (crc 6e7d3fde):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4574 [inline]
    slab_alloc_node mm/slub.c:4898 [inline]
    __kmalloc_cache_noprof+0x371/0x480 mm/slub.c:5414
    kmalloc_noprof include/linux/slab.h:950 [inline]
    kzalloc_noprof include/linux/slab.h:1188 [inline]
    init_srcu_struct_fields+0x2c0/0x350 kernel/rcu/srcutree.c:207
    hci_alloc_dev_priv+0x37/0x680 net/bluetooth/hci_core.c:2453
    hci_alloc_dev include/net/bluetooth/hci_core.h:1763 [inline]
    hci_uart_register_dev drivers/bluetooth/hci_ldisc.c:644 [inline]
    hci_uart_set_proto drivers/bluetooth/hci_ldisc.c:720 [inline]
    hci_uart_tty_ioctl+0x173/0x460 drivers/bluetooth/hci_ldisc.c:774
    tty_ioctl+0xaca/0xd60 drivers/tty/tty_io.c:2801
    vfs_ioctl fs/ioctl.c:51 [inline]
    __do_sys_ioctl fs/ioctl.c:597 [inline]
    __se_sys_ioctl fs/ioctl.c:583 [inline]
    __x64_sys_ioctl+0xf4/0x140 fs/ioctl.c:583
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xee/0xf80 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak
unreferenced object (percpu) 0x607e4d93d800 (size 384):
  comm "syz.0.17", pid 5937, jiffies 4294945495
  hex dump (first 32 bytes on cpu 0):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace (crc 593bdea7):
    pcpu_alloc_noprof+0x7c7/0xed0 mm/percpu.c:1896
    init_srcu_struct_fields+0x2eb/0x350 kernel/rcu/srcutree.c:224
    hci_alloc_dev_priv+0x37/0x680 net/bluetooth/hci_core.c:2453
    hci_alloc_dev include/net/bluetooth/hci_core.h:1763 [inline]
    hci_uart_register_dev drivers/bluetooth/hci_ldisc.c:644 [inline]
    hci_uart_set_proto drivers/bluetooth/hci_ldisc.c:720 [inline]
    hci_uart_tty_ioctl+0x173/0x460 drivers/bluetooth/hci_ldisc.c:774
    tty_ioctl+0xaca/0xd60 drivers/tty/tty_io.c:2801
    vfs_ioctl fs/ioctl.c:51 [inline]
    __do_sys_ioctl fs/ioctl.c:597 [inline]
    __se_sys_ioctl fs/ioctl.c:583 [inline]
    __x64_sys_ioctl+0xf4/0x140 fs/ioctl.c:583
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xee/0xf80 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak
unreferenced object (percpu) 0x607e4d93d980 (size 384):
  comm "syz.0.18", pid 5940, jiffies 4294945497
  hex dump (first 32 bytes on cpu 0):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace (crc 593bdea7):
    pcpu_alloc_noprof+0x7c7/0xed0 mm/percpu.c:1896
    init_srcu_struct_fields+0x2eb/0x350 kernel/rcu/srcutree.c:224
    hci_alloc_dev_priv+0x37/0x680 net/bluetooth/hci_core.c:2453
    hci_alloc_dev include/net/bluetooth/hci_core.h:1763 [inline]
    hci_uart_register_dev drivers/bluetooth/hci_ldisc.c:644 [inline]
    hci_uart_set_proto drivers/bluetooth/hci_ldisc.c:720 [inline]
    hci_uart_tty_ioctl+0x173/0x460 drivers/bluetooth/hci_ldisc.c:774
    tty_ioctl+0xaca/0xd60 drivers/tty/tty_io.c:2801
    vfs_ioctl fs/ioctl.c:51 [inline]
    __do_sys_ioctl fs/ioctl.c:597 [inline]
    __se_sys_ioctl fs/ioctl.c:583 [inline]
    __x64_sys_ioctl+0xf4/0x140 fs/ioctl.c:583
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xee/0xf80 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak
unreferenced object 0xffff88811d010a00 (size 512):
  comm "syz.0.19", pid 5951, jiffies 4294945502
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace (crc 2d3d1dd8):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4574 [inline]
    slab_alloc_node mm/slub.c:4898 [inline]
    __kmalloc_cache_noprof+0x371/0x480 mm/slub.c:5414
    kmalloc_noprof include/linux/slab.h:950 [inline]
    kzalloc_noprof include/linux/slab.h:1188 [inline]
    init_srcu_struct_fields+0x2c0/0x350 kernel/rcu/srcutree.c:207
    hci_alloc_dev_priv+0x37/0x680 net/bluetooth/hci_core.c:2453
    hci_alloc_dev include/net/bluetooth/hci_core.h:1763 [inline]
    hci_uart_register_dev drivers/bluetooth/hci_ldisc.c:644 [inline]
    hci_uart_set_proto drivers/bluetooth/hci_ldisc.c:720 [inline]
    hci_uart_tty_ioctl+0x173/0x460 drivers/bluetooth/hci_ldisc.c:774
    tty_ioctl+0xaca/0xd60 drivers/tty/tty_io.c:2801
    vfs_ioctl fs/ioctl.c:51 [inline]
    __do_sys_ioctl fs/ioctl.c:597 [inline]
    __se_sys_ioctl fs/ioctl.c:583 [inline]
    __x64_sys_ioctl+0xf4/0x140 fs/ioctl.c:583
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xee/0xf80 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak
unreferenced object (percpu) 0x607e4d93db00 (size 384):
  comm "syz.0.19", pid 5951, jiffies 4294945502
  hex dump (first 32 bytes on cpu 0):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace (crc 593bdea7):
    pcpu_alloc_noprof+0x7c7/0xed0 mm/percpu.c:1896
    init_srcu_struct_fields+0x2eb/0x350 kernel/rcu/srcutree.c:224
    hci_alloc_dev_priv+0x37/0x680 net/bluetooth/hci_core.c:2453
    hci_alloc_dev include/net/bluetooth/hci_core.h:1763 [inline]
    hci_uart_register_dev drivers/bluetooth/hci_ldisc.c:644 [inline]
    hci_uart_set_proto drivers/bluetooth/hci_ldisc.c:720 [inline]
    hci_uart_tty_ioctl+0x173/0x460 drivers/bluetooth/hci_ldisc.c:774
    tty_ioctl+0xaca/0xd60 drivers/tty/tty_io.c:2801
    vfs_ioctl fs/ioctl.c:51 [inline]
    __do_sys_ioctl fs/ioctl.c:597 [inline]
    __se_sys_ioctl fs/ioctl.c:583 [inline]
    __x64_sys_ioctl+0xf4/0x140 fs/ioctl.c:583
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xee/0xf80 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

connection error: failed to recv *flatrpc.ExecutorMessageRawT: EOF


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

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.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

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

^ permalink raw reply	[flat|nested] 10+ messages in thread
[parent not found: <20260530231803.97278-1-kartikey406@gmail.com>]
[parent not found: <20260530232001.97305-1-kartikey406@gmail.com>]
[parent not found: <20260531001321.98695-1-kartikey406@gmail.com>]
* [PATCH] Bluetooth: fix memory leaks in error path of hci_alloc_dev()
  2026-05-31  1:19 ` syzbot
@ 2026-05-31 14:25 Bharath Reddy
  2026-05-31 14:59 ` [syzbot] [bluetooth?] memory leak in init_srcu_struct_fields syzbot
  -1 siblings, 1 reply; 10+ messages in thread
From: Bharath Reddy @ 2026-05-31 14:25 UTC (permalink / raw)
  To: syzbot+535ecc844591e50588a5
  Cc: kartikey406, linux-kernel, syzkaller-bugs, Bharath Reddy

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

Syzbot caught a percpu memory leak in the SRCU struct when Bluetooth
HCI UART configuration fails early.

The problem boils down to a bypassed destructor. If device setup fails
before hci_register_dev() completes, the HCI_UNREGISTER flag is never
set. Later, when the device is freed, bt_host_release() sees this flag
is missing, skips hci_release_dev(), and jumps straight to kfree(hdev).
This leaks the SRCU memory, which was also incorrectly being cleaned up
in hci_unregister_dev() which is also skipped during an early abort.

To fix this and properly balance the allocation and teardown paths:

1. Move cleanup_srcu_struct() into hci_release_dev() so it directly
   mirrors the allocation in hci_alloc_dev().
2. Unconditionally call hci_release_dev() from bt_host_release() by
   dropping the HCI_UNREGISTER check. This is safe for unregistered
   devices since it only cleans up resources initialized early on in
   hci_alloc_dev().

Reported-by: syzbot+535ecc844591e50588a5@syzkaller.appspotmail.com

Signed-off-by: Bharath Reddy <kbreddy.rpbc@gmail.com>
---
 net/bluetooth/hci_core.c  | 3 ++-
 net/bluetooth/hci_sysfs.c | 6 ++----
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index c46c1236ebfa..f6bc7cb3e55c 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -2701,7 +2701,6 @@ void hci_unregister_dev(struct hci_dev *hdev)
 	write_unlock(&hci_dev_list_lock);
 
 	synchronize_srcu(&hdev->srcu);
-	cleanup_srcu_struct(&hdev->srcu);
 
 	disable_work_sync(&hdev->rx_work);
 	disable_work_sync(&hdev->cmd_work);
@@ -2774,6 +2773,8 @@ void hci_release_dev(struct hci_dev *hdev)
 	kfree_skb(hdev->sent_cmd);
 	kfree_skb(hdev->req_skb);
 	kfree_skb(hdev->recv_event);
+
+	cleanup_srcu_struct(&hdev->srcu);
 	kfree(hdev);
 }
 EXPORT_SYMBOL(hci_release_dev);
diff --git a/net/bluetooth/hci_sysfs.c b/net/bluetooth/hci_sysfs.c
index 041ce9adc378..261b28a25b02 100644
--- a/net/bluetooth/hci_sysfs.c
+++ b/net/bluetooth/hci_sysfs.c
@@ -83,10 +83,8 @@ static void bt_host_release(struct device *dev)
 {
 	struct hci_dev *hdev = to_hci_dev(dev);
 
-	if (hci_dev_test_flag(hdev, HCI_UNREGISTER))
-		hci_release_dev(hdev);
-	else
-		kfree(hdev);
+	hci_release_dev(hdev);
+
 	module_put(THIS_MODULE);
 }
 
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 10+ messages in thread
* [PATCH] Bluetooth: fix memory leaks in error path of hci_alloc_dev()
  2026-05-31  1:19 ` syzbot
@ 2026-05-31 14:41 Bharath Reddy
  2026-05-31 15:27 ` [syzbot] [bluetooth?] memory leak in init_srcu_struct_fields syzbot
  -1 siblings, 1 reply; 10+ messages in thread
From: Bharath Reddy @ 2026-05-31 14:41 UTC (permalink / raw)
  To: syzbot+535ecc844591e50588a5
  Cc: kartikey406, linux-kernel, syzkaller-bugs, Bharath Reddy

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git f377d0025eb0

Syzbot caught a percpu memory leak in the SRCU struct when Bluetooth
HCI UART configuration fails early.

The problem boils down to a bypassed destructor. If device setup fails
before hci_register_dev() completes, the HCI_UNREGISTER flag is never
set. Later, when the device is freed, bt_host_release() sees this flag
is missing, skips hci_release_dev(), and jumps straight to kfree(hdev).
This leaks the SRCU memory, which was also incorrectly being cleaned up
in hci_unregister_dev() which is also skipped during an early abort.

To fix this and properly balance the allocation and teardown paths:

1. Move cleanup_srcu_struct() into hci_release_dev() so it directly
   mirrors the allocation in hci_alloc_dev().
2. Unconditionally call hci_release_dev() from bt_host_release() by
   dropping the HCI_UNREGISTER check. This is safe for unregistered
   devices since it only cleans up resources initialized early on in
   hci_alloc_dev().

Reported-by: syzbot+535ecc844591e50588a5@syzkaller.appspotmail.com

Signed-off-by: Bharath Reddy <kbreddy.rpbc@gmail.com>
---
 net/bluetooth/hci_core.c  | 3 ++-
 net/bluetooth/hci_sysfs.c | 6 ++----
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index c46c1236ebfa..f6bc7cb3e55c 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -2701,7 +2701,6 @@ void hci_unregister_dev(struct hci_dev *hdev)
 	write_unlock(&hci_dev_list_lock);
 
 	synchronize_srcu(&hdev->srcu);
-	cleanup_srcu_struct(&hdev->srcu);
 
 	disable_work_sync(&hdev->rx_work);
 	disable_work_sync(&hdev->cmd_work);
@@ -2774,6 +2773,8 @@ void hci_release_dev(struct hci_dev *hdev)
 	kfree_skb(hdev->sent_cmd);
 	kfree_skb(hdev->req_skb);
 	kfree_skb(hdev->recv_event);
+
+	cleanup_srcu_struct(&hdev->srcu);
 	kfree(hdev);
 }
 EXPORT_SYMBOL(hci_release_dev);
diff --git a/net/bluetooth/hci_sysfs.c b/net/bluetooth/hci_sysfs.c
index 041ce9adc378..261b28a25b02 100644
--- a/net/bluetooth/hci_sysfs.c
+++ b/net/bluetooth/hci_sysfs.c
@@ -83,10 +83,8 @@ static void bt_host_release(struct device *dev)
 {
 	struct hci_dev *hdev = to_hci_dev(dev);
 
-	if (hci_dev_test_flag(hdev, HCI_UNREGISTER))
-		hci_release_dev(hdev);
-	else
-		kfree(hdev);
+	hci_release_dev(hdev);
+
 	module_put(THIS_MODULE);
 }
 
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 10+ messages in thread
* [PATCH v2] Bluetooth: fix memory leak in error path of hci_alloc_dev()
  2026-05-31  1:19 ` syzbot
@ 2026-05-31 15:27 Bharath Reddy
  2026-05-31 16:11 ` [syzbot] [bluetooth?] memory leak in init_srcu_struct_fields syzbot
  -1 siblings, 1 reply; 10+ messages in thread
From: Bharath Reddy @ 2026-05-31 15:27 UTC (permalink / raw)
  To: syzbot+535ecc844591e50588a5
  Cc: kartikey406, linux-kernel, syzkaller-bugs, Bharath Reddy

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git f377d0025eb0

Early failures in Bluetooth HCI UART configuration leak SRCU percpu
memory.

When device initialization fails before hci_register_dev() completes,
the HCI_UNREGISTER flag is never set. As a result, when the device
reference count reaches zero, bt_host_release() evaluates this flag as
false and falls back to a direct kfree(hdev).

Because hci_release_dev() is bypassed, the SRCU struct initialized
early in hci_alloc_dev() is never cleaned up, resulting in a leak of
percpu memory.

Fix the leak by explicitly calling cleanup_srcu_struct() in the
fallback (unregistered) branch of bt_host_release() before freeing
the device.

Reported-by: syzbot+535ecc844591e50588a5@syzkaller.appspotmail.com

Signed-off-by: Bharath Reddy <kbreddy.rpbc@gmail.com>
---
 net/bluetooth/hci_sysfs.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/bluetooth/hci_sysfs.c b/net/bluetooth/hci_sysfs.c
index 041ce9adc378..74131f2c3be6 100644
--- a/net/bluetooth/hci_sysfs.c
+++ b/net/bluetooth/hci_sysfs.c
@@ -85,8 +85,10 @@ static void bt_host_release(struct device *dev)
 
 	if (hci_dev_test_flag(hdev, HCI_UNREGISTER))
 		hci_release_dev(hdev);
-	else
+	else {
+		cleanup_srcu_struct(&hdev->srcu);
 		kfree(hdev);
+	}
 	module_put(THIS_MODULE);
 }
 
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 10+ messages in thread
end of thread, other threads:[~2026-05-31 16:11 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-05-30 20:57 [syzbot] [bluetooth?] memory leak in init_srcu_struct_fields syzbot
2026-05-30 23:18 ` Forwarded: [PATCH] Bluetooth: hci_core: Fix SRCU leak when device is freed unregistered syzbot
2026-05-30 23:20 ` syzbot
2026-05-31  0:13 ` syzbot
     [not found] <20260530231803.97278-1-kartikey406@gmail.com>
2026-05-31  0:13 ` [syzbot] [bluetooth?] memory leak in init_srcu_struct_fields syzbot
     [not found] <20260530232001.97305-1-kartikey406@gmail.com>
2026-05-31  0:21 ` syzbot
     [not found] <20260531001321.98695-1-kartikey406@gmail.com>
2026-05-31  1:19 ` syzbot
  -- strict thread matches above, loose matches on Subject: below --
2026-05-31 14:25 [PATCH] Bluetooth: fix memory leaks in error path of hci_alloc_dev() Bharath Reddy
2026-05-31 14:59 ` [syzbot] [bluetooth?] memory leak in init_srcu_struct_fields syzbot
2026-05-31 14:41 [PATCH] Bluetooth: fix memory leaks in error path of hci_alloc_dev() Bharath Reddy
2026-05-31 15:27 ` [syzbot] [bluetooth?] memory leak in init_srcu_struct_fields syzbot
2026-05-31 15:27 [PATCH v2] Bluetooth: fix memory leak in error path of hci_alloc_dev() Bharath Reddy
2026-05-31 16:11 ` [syzbot] [bluetooth?] memory leak in init_srcu_struct_fields syzbot

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