[syzbot] [usb?] memory leak in hub_event (4)

[syzbot] [usb?] memory leak in hub_event (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    dd6c438c3e64 Merge tag 'vfs-7.1-rc1.fixes' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15cf7702580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ac5083db84233db3
dashboard link: https://syzkaller.appspot.com/bug?extid=2afd7e71155c7e241560
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=13cf7702580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17941c36580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/dea6ab846ab3/disk-dd6c438c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/acebe380aa03/vmlinux-dd6c438c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2cdbd012d0d3/bzImage-dd6c438c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2afd7e71155c7e241560@syzkaller.appspotmail.com

BUG: memory leak
unreferenced object 0xffff8881277dc000 (size 2048):
  comm "kworker/0:2", pid 1783, jiffies 4294946784
  hex dump (first 32 bytes):
    ff ff ff ff 31 00 00 00 00 00 00 00 00 00 00 00  ....1...........
    00 00 00 00 00 00 00 00 00 00 00 00 02 00 00 00  ................
  backtrace (crc 20105372):
    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:5410
    kmalloc_noprof include/linux/slab.h:950 [inline]
    kzalloc_noprof include/linux/slab.h:1188 [inline]
    usb_alloc_dev+0x36/0x4e0 drivers/usb/core/usb.c:651
    hub_port_connect drivers/usb/core/hub.c:5470 [inline]
    hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
    port_event drivers/usb/core/hub.c:5871 [inline]
    hub_event+0x14d0/0x2180 drivers/usb/core/hub.c:5953
    process_one_work+0x277/0x5b0 kernel/workqueue.c:3302
    process_scheduled_works kernel/workqueue.c:3385 [inline]
    worker_thread+0x255/0x4a0 kernel/workqueue.c:3466
    kthread+0x14e/0x1a0 kernel/kthread.c:436
    ret_from_fork+0x219/0x490 arch/x86/kernel/process.c:158
    ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

BUG: memory leak
unreferenced object 0xffff888128b06c00 (size 1024):
  comm "kworker/0:2", pid 1783, jiffies 4294946815
  hex dump (first 32 bytes):
    09 02 49 00 02 01 00 10 40 00 00 00 00 00 00 00  ..I.....@.......
    00 00 00 00 00 00 00 00 89 b8 69 09 81 88 ff ff  ..........i.....
  backtrace (crc b43c3ef8):
    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]
    __do_kmalloc_node mm/slub.c:5294 [inline]
    __kmalloc_noprof+0x3b7/0x550 mm/slub.c:5307
    kmalloc_noprof include/linux/slab.h:954 [inline]
    kzalloc_noprof include/linux/slab.h:1188 [inline]
    usb_get_configuration+0xeb/0x2110 drivers/usb/core/config.c:940
    usb_enumerate_device drivers/usb/core/hub.c:2527 [inline]
    usb_new_device+0x1b4/0x300 drivers/usb/core/hub.c:2665
    hub_port_connect drivers/usb/core/hub.c:5567 [inline]
    hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
    port_event drivers/usb/core/hub.c:5871 [inline]
    hub_event+0x1723/0x2180 drivers/usb/core/hub.c:5953
    process_one_work+0x277/0x5b0 kernel/workqueue.c:3302
    process_scheduled_works kernel/workqueue.c:3385 [inline]
    worker_thread+0x255/0x4a0 kernel/workqueue.c:3466
    kthread+0x14e/0x1a0 kernel/kthread.c:436
    ret_from_fork+0x219/0x490 arch/x86/kernel/process.c:158
    ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

BUG: memory leak
unreferenced object 0xffff88810c3d5a50 (size 8):
  comm "kworker/0:2", pid 1783, jiffies 4294946815
  hex dump (first 8 bytes):
    80 b8 69 09 81 88 ff ff                          ..i.....
  backtrace (crc 66af3167):
    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]
    __do_kmalloc_node mm/slub.c:5294 [inline]
    __kmalloc_noprof+0x3b7/0x550 mm/slub.c:5307
    kmalloc_noprof include/linux/slab.h:954 [inline]
    kzalloc_noprof include/linux/slab.h:1188 [inline]
    usb_get_configuration+0x11d/0x2110 drivers/usb/core/config.c:945
    usb_enumerate_device drivers/usb/core/hub.c:2527 [inline]
    usb_new_device+0x1b4/0x300 drivers/usb/core/hub.c:2665
    hub_port_connect drivers/usb/core/hub.c:5567 [inline]
    hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
    port_event drivers/usb/core/hub.c:5871 [inline]
    hub_event+0x1723/0x2180 drivers/usb/core/hub.c:5953
    process_one_work+0x277/0x5b0 kernel/workqueue.c:3302
    process_scheduled_works kernel/workqueue.c:3385 [inline]
    worker_thread+0x255/0x4a0 kernel/workqueue.c:3466
    kthread+0x14e/0x1a0 kernel/kthread.c:436
    ret_from_fork+0x219/0x490 arch/x86/kernel/process.c:158
    ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

BUG: memory leak
unreferenced object 0xffff888113c25840 (size 64):
  comm "kworker/0:2", pid 1783, jiffies 4294946817
  hex dump (first 32 bytes):
    01 00 00 00 01 00 00 00 09 04 00 00 00 01 01 30  ...............0
    00 00 00 00 0a 00 00 00 9a b8 69 09 81 88 ff ff  ..........i.....
  backtrace (crc a90fa323):
    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]
    __do_kmalloc_node mm/slub.c:5294 [inline]
    __kmalloc_noprof+0x3b7/0x550 mm/slub.c:5307
    kmalloc_noprof include/linux/slab.h:954 [inline]
    kzalloc_noprof include/linux/slab.h:1188 [inline]
    usb_parse_configuration drivers/usb/core/config.c:826 [inline]
    usb_get_configuration+0x88f/0x2110 drivers/usb/core/config.c:1002
    usb_enumerate_device drivers/usb/core/hub.c:2527 [inline]
    usb_new_device+0x1b4/0x300 drivers/usb/core/hub.c:2665
    hub_port_connect drivers/usb/core/hub.c:5567 [inline]
    hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
    port_event drivers/usb/core/hub.c:5871 [inline]
    hub_event+0x1723/0x2180 drivers/usb/core/hub.c:5953
    process_one_work+0x277/0x5b0 kernel/workqueue.c:3302
    process_scheduled_works kernel/workqueue.c:3385 [inline]
    worker_thread+0x255/0x4a0 kernel/workqueue.c:3466
    kthread+0x14e/0x1a0 kernel/kthread.c:436
    ret_from_fork+0x219/0x490 arch/x86/kernel/process.c:158
    ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

BUG: memory leak
unreferenced object 0xffff88811d54a500 (size 256):
  comm "kworker/0:2", pid 1783, jiffies 4294946821
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 08 a5 54 1d 81 88 ff ff  ..........T.....
    08 a5 54 1d 81 88 ff ff 20 e7 41 83 ff ff ff ff  ..T..... .A.....
  backtrace (crc 85d09f91):
    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:5410
    kmalloc_noprof include/linux/slab.h:950 [inline]
    kzalloc_noprof include/linux/slab.h:1188 [inline]
    device_private_init drivers/base/core.c:3536 [inline]
    device_add+0x73c/0xc70 drivers/base/core.c:3587
    usb_new_device.cold+0x115/0x626 drivers/usb/core/hub.c:2695
    hub_port_connect drivers/usb/core/hub.c:5567 [inline]
    hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
    port_event drivers/usb/core/hub.c:5871 [inline]
    hub_event+0x1723/0x2180 drivers/usb/core/hub.c:5953
    process_one_work+0x277/0x5b0 kernel/workqueue.c:3302
    process_scheduled_works kernel/workqueue.c:3385 [inline]
    worker_thread+0x255/0x4a0 kernel/workqueue.c:3466
    kthread+0x14e/0x1a0 kernel/kthread.c:436
    ret_from_fork+0x219/0x490 arch/x86/kernel/process.c:158
    ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

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


---
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If the report is already addressed, let syzbot know by replying with:
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If you want syzbot to run the reproducer, reply with:
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Re: [syzbot] [usb?] memory leak in hub_event (4)

[Oliver Neukum]

[-- Attachment #1: Type: text/plain, Size: 81 bytes --]

On 25.04.26 04:12, syzbot wrote:

#syz test: git://repo/address.git dd6c438c3e64

[-- Attachment #2: 0001-usb-core-fix-memory-of-error-case-in-usb_get_configu.patch --]
[-- Type: text/x-patch, Size: 1527 bytes --]

From 001175f4d2e1c2ceac98b4af2521fc4d0253d0c8 Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oneukum@suse.com>
Date: Mon, 27 Apr 2026 13:35:38 +0200
Subject: [PATCH] usb: core: fix memory of error case in usb_get_configuration

Prior allocations need to be reversed if subsequent
allocations fail.

Fixes: dd2057e544dc9 ("USB: core: drop OOM message")
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Reported-by: syzbot+2afd7e71155c7e241560@syzkaller.appspotmail.com
---
 drivers/usb/core/config.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
index 417140b012bb..67475ff81641 100644
--- a/drivers/usb/core/config.c
+++ b/drivers/usb/core/config.c
@@ -944,11 +944,11 @@ int usb_get_configuration(struct usb_device *dev)
 	length = ncfg * sizeof(char *);
 	dev->rawdescriptors = kzalloc(length, GFP_KERNEL);
 	if (!dev->rawdescriptors)
-		return -ENOMEM;
+		goto bailout2;
 
 	desc = kmalloc(USB_DT_CONFIG_SIZE, GFP_KERNEL);
 	if (!desc)
-		return -ENOMEM;
+		goto bailout;
 
 	for (cfgno = 0; cfgno < ncfg; cfgno++) {
 		/* We grab just the first descriptor so we know how long
@@ -1012,6 +1012,15 @@ int usb_get_configuration(struct usb_device *dev)
 	dev->descriptor.bNumConfigurations = cfgno;
 
 	return result;
+
+bailout:
+	kfree(dev->rawdescriptors);
+	dev->rawdescriptors = NULL;
+bailout2:
+	kfree(dev->config);
+	dev->config = NULL;
+
+	return -ENOMEM;
 }
 
 void usb_release_bos_descriptor(struct usb_device *dev)
-- 
2.54.0

Re: [syzbot] [usb?] memory leak in hub_event (4)

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

failed to checkout kernel repo git://repo/address.git on commit dd6c438c3e64: failed to run ["git" "fetch" "--force" "--tags" "b7cf8f2fbfc36c709a08e0b9c77990e491473738"]: exit status 128


Tested on:

commit:         [unknown 
git tree:       git://repo/address.git dd6c438c3e64
kernel config:  https://syzkaller.appspot.com/x/.config?x=ac5083db84233db3
dashboard link: https://syzkaller.appspot.com/bug?extid=2afd7e71155c7e241560
compiler:       
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1575b236580000

Re: [syzbot] [usb?] memory leak in hub_event (4)

[Alan Stern]

On Mon, Apr 27, 2026 at 01:40:02PM +0200, Oliver Neukum wrote:
> On 25.04.26 04:12, syzbot wrote:
> 
> #syz test: git://repo/address.git dd6c438c3e64

> From 001175f4d2e1c2ceac98b4af2521fc4d0253d0c8 Mon Sep 17 00:00:00 2001
> From: Oliver Neukum <oneukum@suse.com>
> Date: Mon, 27 Apr 2026 13:35:38 +0200
> Subject: [PATCH] usb: core: fix memory of error case in usb_get_configuration
> 
> Prior allocations need to be reversed if subsequent
> allocations fail.
> 
> Fixes: dd2057e544dc9 ("USB: core: drop OOM message")
> Signed-off-by: Oliver Neukum <oneukum@suse.com>
> Reported-by: syzbot+2afd7e71155c7e241560@syzkaller.appspotmail.com
> ---
>  drivers/usb/core/config.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
> index 417140b012bb..67475ff81641 100644
> --- a/drivers/usb/core/config.c
> +++ b/drivers/usb/core/config.c
> @@ -944,11 +944,11 @@ int usb_get_configuration(struct usb_device *dev)
>  	length = ncfg * sizeof(char *);
>  	dev->rawdescriptors = kzalloc(length, GFP_KERNEL);
>  	if (!dev->rawdescriptors)
> -		return -ENOMEM;
> +		goto bailout2;
>  
>  	desc = kmalloc(USB_DT_CONFIG_SIZE, GFP_KERNEL);
>  	if (!desc)
> -		return -ENOMEM;
> +		goto bailout;
>  
>  	for (cfgno = 0; cfgno < ncfg; cfgno++) {
>  		/* We grab just the first descriptor so we know how long
> @@ -1012,6 +1012,15 @@ int usb_get_configuration(struct usb_device *dev)
>  	dev->descriptor.bNumConfigurations = cfgno;
>  
>  	return result;
> +
> +bailout:
> +	kfree(dev->rawdescriptors);
> +	dev->rawdescriptors = NULL;
> +bailout2:
> +	kfree(dev->config);
> +	dev->config = NULL;
> +
> +	return -ENOMEM;
>  }

This is not needed.  dev->rawdescriptors and dev->config are deallocated 
in usb_destroy_configuration(), which gets called when the usb_device 
structure is released.

The memory leak must have a different cause.

Alan Stern