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* [syzbot] [mm?] WARNING in ep_write_iter
@ 2026-08-16 19:25 syzbot
  2026-08-16 20:52 ` Andrew Morton
  0 siblings, 1 reply; 4+ messages in thread
From: syzbot @ 2026-08-16 19:25 UTC (permalink / raw)
  To: akpm, apopple, byungchul, david, gourry, joshua.hahnjy,
	linux-kernel, linux-mm, matthew.brost, rakie.kim, syzkaller-bugs,
	ying.huang, ziy

Hello,

syzbot found the following issue on:

HEAD commit:    3d6d817622b0 Merge tag 'scsi-fixes' of git://git.kernel.or..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15927479580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a59830cba91a1981
dashboard link: https://syzkaller.appspot.com/bug?extid=805630f1453e490427fa
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-3d6d8176.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d19e0514c02a/vmlinux-3d6d8176.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f6da706811f4/bzImage-3d6d8176.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+805630f1453e490427fa@syzkaller.appspotmail.com

gadgetfs: bound to dummy_udc driver
------------[ cut here ]------------
1
WARNING: mm/page_alloc.c:5280 at __alloc_frozen_pages_noprof+0x2ce/0x380 mm/page_alloc.c:5280, CPU#0: syz.0.0/5319
Modules linked in:
CPU: 0 UID: 0 PID: 5319 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
RIP: 0010:__alloc_frozen_pages_noprof+0x2ce/0x380 mm/page_alloc.c:5280
Code: 74 10 4c 89 e7 89 54 24 0c e8 0e 2c 0e 00 8b 54 24 0c 49 83 3c 24 00 0f 85 ab fe ff ff e9 ac fe ff ff c6 05 95 d2 18 0e 01 90 <0f> 0b 90 e9 17 ff ff ff a9 00 00 08 00 48 8b 4c 24 10 4c 8d 44 24
RSP: 0018:ffffc9000e13fa20 EFLAGS: 00010246
RAX: ffffc9000e13fa00 RBX: 0000000000000013 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffc9000e13fa88
RBP: ffffc9000e13fb08 R08: ffffc9000e13fa87 R09: 0000000000000000
R10: ffffc9000e13fa60 R11: fffff52001c27f51 R12: 0000000000000000
R13: 1ffff92001c27f48 R14: 0000000000040cc0 R15: dffffc0000000000
FS:  00007f6f4a58c6c0(0000) GS:ffff88808c549000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000000010a0 CR3: 000000004323d000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 alloc_pages_mpol+0x212/0x380 mm/mempolicy.c:2490
 ___kmalloc_large_node+0x4c/0x120 mm/slub.c:5274
 __kmalloc_large_node_noprof+0x18/0x90 mm/slub.c:5305
 __do_kmalloc_node mm/slub.c:5322 [inline]
 __kmalloc_noprof+0x405/0x720 mm/slub.c:5359
 _kmalloc_noprof include/linux/slab.h:992 [inline]
 ep_write_iter+0x1bc/0x500 drivers/usb/gadget/legacy/inode.c:669
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x612/0xba0 fs/read_write.c:687
 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: 0033:0x7f6f4979e0d9
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:00007f6f4a58bfe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f6f49a25fa0 RCX: 00007f6f4979e0d9
RDX: 00000000ffffffb9 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007f6f49835024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6f49a26038 R14: 00007f6f49a25fa0 R15: 00007ffc6cf49328
 </TASK>


---
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 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] 4+ messages in thread

* Re: [syzbot] [mm?] WARNING in ep_write_iter
  2026-08-16 19:25 [syzbot] [mm?] WARNING in ep_write_iter syzbot
@ 2026-08-16 20:52 ` Andrew Morton
  2026-08-16 21:47   ` Zi Yan
  0 siblings, 1 reply; 4+ messages in thread
From: Andrew Morton @ 2026-08-16 20:52 UTC (permalink / raw)
  To: syzbot
  Cc: apopple, byungchul, david, gourry, joshua.hahnjy, linux-kernel,
	linux-mm, matthew.brost, rakie.kim, syzkaller-bugs, ying.huang,
	ziy, Greg Kroah-Hartman, linux-usb

On Sun, 16 Aug 2026 12:25:48 -0700 syzbot <syzbot+805630f1453e490427fa@syzkaller.appspotmail.com> wrote:

> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    3d6d817622b0 Merge tag 'scsi-fixes' of git://git.kernel.or..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=15927479580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=a59830cba91a1981
> dashboard link: https://syzkaller.appspot.com/bug?extid=805630f1453e490427fa
> 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-3d6d8176.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/d19e0514c02a/vmlinux-3d6d8176.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/f6da706811f4/bzImage-3d6d8176.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+805630f1453e490427fa@syzkaller.appspotmail.com
> 
> gadgetfs: bound to dummy_udc driver
> ------------[ cut here ]------------
> 1
> WARNING: mm/page_alloc.c:5280 at __alloc_frozen_pages_noprof+0x2ce/0x380 mm/page_alloc.c:5280, CPU#0: syz.0.0/5319

Thanks.  drivers/usb/gadget is the offender.

Gemini sums it up well.  "ep_write_iter() needs a bounds check prior to
memory allocation".  https://share.gemini.google/5NzjyttO0ULc

I expect an easy fix would be

--- a/drivers/usb/gadget/legacy/inode.c~a
+++ a/drivers/usb/gadget/legacy/inode.c
@@ -666,7 +666,7 @@ ep_write_iter(struct kiocb *iocb, struct
 		return -EBADMSG;
 	}
 
-	buf = kmalloc(len, GFP_KERNEL);
+	buf = kmalloc(len, GFP_KERNEL|__GFP_NOWARN);
 	if (unlikely(!buf)) {
 		mutex_unlock(&epdata->lock);
 		return -ENOMEM;

or do what Gemini said.  Me, I'll add some cc's and run away.


> Modules linked in:
> CPU: 0 UID: 0 PID: 5319 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
> RIP: 0010:__alloc_frozen_pages_noprof+0x2ce/0x380 mm/page_alloc.c:5280
> Code: 74 10 4c 89 e7 89 54 24 0c e8 0e 2c 0e 00 8b 54 24 0c 49 83 3c 24 00 0f 85 ab fe ff ff e9 ac fe ff ff c6 05 95 d2 18 0e 01 90 <0f> 0b 90 e9 17 ff ff ff a9 00 00 08 00 48 8b 4c 24 10 4c 8d 44 24
> RSP: 0018:ffffc9000e13fa20 EFLAGS: 00010246
> RAX: ffffc9000e13fa00 RBX: 0000000000000013 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffc9000e13fa88
> RBP: ffffc9000e13fb08 R08: ffffc9000e13fa87 R09: 0000000000000000
> R10: ffffc9000e13fa60 R11: fffff52001c27f51 R12: 0000000000000000
> R13: 1ffff92001c27f48 R14: 0000000000040cc0 R15: dffffc0000000000
> FS:  00007f6f4a58c6c0(0000) GS:ffff88808c549000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00002000000010a0 CR3: 000000004323d000 CR4: 0000000000352ef0
> Call Trace:
>  <TASK>
>  alloc_pages_mpol+0x212/0x380 mm/mempolicy.c:2490
>  ___kmalloc_large_node+0x4c/0x120 mm/slub.c:5274
>  __kmalloc_large_node_noprof+0x18/0x90 mm/slub.c:5305
>  __do_kmalloc_node mm/slub.c:5322 [inline]
>  __kmalloc_noprof+0x405/0x720 mm/slub.c:5359
>  _kmalloc_noprof include/linux/slab.h:992 [inline]
>  ep_write_iter+0x1bc/0x500 drivers/usb/gadget/legacy/inode.c:669
>  new_sync_write fs/read_write.c:595 [inline]
>  vfs_write+0x612/0xba0 fs/read_write.c:687
>  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: 0033:0x7f6f4979e0d9
> 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:00007f6f4a58bfe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 00007f6f49a25fa0 RCX: 00007f6f4979e0d9
> RDX: 00000000ffffffb9 RSI: 0000000000000000 RDI: 0000000000000004
> RBP: 00007f6f49835024 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007f6f49a26038 R14: 00007f6f49a25fa0 R15: 00007ffc6cf49328
>  </TASK>
> 


^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [syzbot] [mm?] WARNING in ep_write_iter
  2026-08-16 20:52 ` Andrew Morton
@ 2026-08-16 21:47   ` Zi Yan
  2026-08-16 23:32     ` Alan Stern
  0 siblings, 1 reply; 4+ messages in thread
From: Zi Yan @ 2026-08-16 21:47 UTC (permalink / raw)
  To: Andrew Morton, syzbot
  Cc: apopple, byungchul, david, gourry, joshua.hahnjy, linux-kernel,
	linux-mm, matthew.brost, rakie.kim, syzkaller-bugs, ying.huang,
	Greg Kroah-Hartman, linux-usb

On Sun Aug 16, 2026 at 4:52 PM EDT, Andrew Morton wrote:
> On Sun, 16 Aug 2026 12:25:48 -0700 syzbot <syzbot+805630f1453e490427fa@syzkaller.appspotmail.com> wrote:
>
>> Hello,
>> 
>> syzbot found the following issue on:
>> 
>> HEAD commit:    3d6d817622b0 Merge tag 'scsi-fixes' of git://git.kernel.or..
>> git tree:       upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=15927479580000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=a59830cba91a1981
>> dashboard link: https://syzkaller.appspot.com/bug?extid=805630f1453e490427fa
>> 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-3d6d8176.raw.xz
>> vmlinux: https://storage.googleapis.com/syzbot-assets/d19e0514c02a/vmlinux-3d6d8176.xz
>> kernel image: https://storage.googleapis.com/syzbot-assets/f6da706811f4/bzImage-3d6d8176.xz
>> 
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: syzbot+805630f1453e490427fa@syzkaller.appspotmail.com
>> 
>> gadgetfs: bound to dummy_udc driver
>> ------------[ cut here ]------------
>> 1
>> WARNING: mm/page_alloc.c:5280 at __alloc_frozen_pages_noprof+0x2ce/0x380 mm/page_alloc.c:5280, CPU#0: syz.0.0/5319
>
> Thanks.  drivers/usb/gadget is the offender.
>
> Gemini sums it up well.  "ep_write_iter() needs a bounds check prior to
> memory allocation".  https://share.gemini.google/5NzjyttO0ULc
>
> I expect an easy fix would be

Maybe it is better to stop asking kmalloc for unreasonable len:


diff --git a/drivers/usb/gadget/legacy/inode.c b/drivers/usb/gadget/legacy/inode.c
index d87a8ab515107..20905f254968f 100644
--- a/drivers/usb/gadget/legacy/inode.c
+++ b/drivers/usb/gadget/legacy/inode.c
@@ -645,6 +645,9 @@ ep_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	ssize_t value;
 	char *buf;
 
+	if (len > KMALLOC_MAX_SIZE)
+		return -EINVAL;
+
 	if ((value = get_ready_ep(file->f_flags, epdata, true)) < 0)
 		return value;

>
> --- a/drivers/usb/gadget/legacy/inode.c~a
> +++ a/drivers/usb/gadget/legacy/inode.c
> @@ -666,7 +666,7 @@ ep_write_iter(struct kiocb *iocb, struct
>  		return -EBADMSG;
>  	}
>  
> -	buf = kmalloc(len, GFP_KERNEL);
> +	buf = kmalloc(len, GFP_KERNEL|__GFP_NOWARN);
>  	if (unlikely(!buf)) {
>  		mutex_unlock(&epdata->lock);
>  		return -ENOMEM;
>
> or do what Gemini said.  Me, I'll add some cc's and run away.
>
>
>> Modules linked in:
>> CPU: 0 UID: 0 PID: 5319 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
>> RIP: 0010:__alloc_frozen_pages_noprof+0x2ce/0x380 mm/page_alloc.c:5280
>> Code: 74 10 4c 89 e7 89 54 24 0c e8 0e 2c 0e 00 8b 54 24 0c 49 83 3c 24 00 0f 85 ab fe ff ff e9 ac fe ff ff c6 05 95 d2 18 0e 01 90 <0f> 0b 90 e9 17 ff ff ff a9 00 00 08 00 48 8b 4c 24 10 4c 8d 44 24
>> RSP: 0018:ffffc9000e13fa20 EFLAGS: 00010246
>> RAX: ffffc9000e13fa00 RBX: 0000000000000013 RCX: 0000000000000000
>> RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffc9000e13fa88
>> RBP: ffffc9000e13fb08 R08: ffffc9000e13fa87 R09: 0000000000000000
>> R10: ffffc9000e13fa60 R11: fffff52001c27f51 R12: 0000000000000000
>> R13: 1ffff92001c27f48 R14: 0000000000040cc0 R15: dffffc0000000000
>> FS:  00007f6f4a58c6c0(0000) GS:ffff88808c549000(0000) knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 00002000000010a0 CR3: 000000004323d000 CR4: 0000000000352ef0
>> Call Trace:
>>  <TASK>
>>  alloc_pages_mpol+0x212/0x380 mm/mempolicy.c:2490
>>  ___kmalloc_large_node+0x4c/0x120 mm/slub.c:5274
>>  __kmalloc_large_node_noprof+0x18/0x90 mm/slub.c:5305
>>  __do_kmalloc_node mm/slub.c:5322 [inline]
>>  __kmalloc_noprof+0x405/0x720 mm/slub.c:5359
>>  _kmalloc_noprof include/linux/slab.h:992 [inline]
>>  ep_write_iter+0x1bc/0x500 drivers/usb/gadget/legacy/inode.c:669
>>  new_sync_write fs/read_write.c:595 [inline]
>>  vfs_write+0x612/0xba0 fs/read_write.c:687
>>  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: 0033:0x7f6f4979e0d9
>> 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:00007f6f4a58bfe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
>> RAX: ffffffffffffffda RBX: 00007f6f49a25fa0 RCX: 00007f6f4979e0d9
>> RDX: 00000000ffffffb9 RSI: 0000000000000000 RDI: 0000000000000004
>> RBP: 00007f6f49835024 R08: 0000000000000000 R09: 0000000000000000
>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
>> R13: 00007f6f49a26038 R14: 00007f6f49a25fa0 R15: 00007ffc6cf49328
>>  </TASK>
>> 




-- 
Best Regards,
Yan, Zi


^ permalink raw reply related	[flat|nested] 4+ messages in thread

* Re: [syzbot] [mm?] WARNING in ep_write_iter
  2026-08-16 21:47   ` Zi Yan
@ 2026-08-16 23:32     ` Alan Stern
  0 siblings, 0 replies; 4+ messages in thread
From: Alan Stern @ 2026-08-16 23:32 UTC (permalink / raw)
  To: Zi Yan
  Cc: Andrew Morton, syzbot, apopple, byungchul, david, gourry,
	joshua.hahnjy, linux-kernel, linux-mm, matthew.brost, rakie.kim,
	syzkaller-bugs, ying.huang, Greg Kroah-Hartman, linux-usb

On Sun, Aug 16, 2026 at 05:47:34PM -0400, Zi Yan wrote:
> On Sun Aug 16, 2026 at 4:52 PM EDT, Andrew Morton wrote:
> > On Sun, 16 Aug 2026 12:25:48 -0700 syzbot <syzbot+805630f1453e490427fa@syzkaller.appspotmail.com> wrote:
> >
> >> Hello,
> >> 
> >> syzbot found the following issue on:
> >> 
> >> HEAD commit:    3d6d817622b0 Merge tag 'scsi-fixes' of git://git.kernel.or..
> >> git tree:       upstream
> >> console output: https://syzkaller.appspot.com/x/log.txt?x=15927479580000
> >> kernel config:  https://syzkaller.appspot.com/x/.config?x=a59830cba91a1981
> >> dashboard link: https://syzkaller.appspot.com/bug?extid=805630f1453e490427fa
> >> 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-3d6d8176.raw.xz
> >> vmlinux: https://storage.googleapis.com/syzbot-assets/d19e0514c02a/vmlinux-3d6d8176.xz
> >> kernel image: https://storage.googleapis.com/syzbot-assets/f6da706811f4/bzImage-3d6d8176.xz
> >> 
> >> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> >> Reported-by: syzbot+805630f1453e490427fa@syzkaller.appspotmail.com
> >> 
> >> gadgetfs: bound to dummy_udc driver
> >> ------------[ cut here ]------------
> >> 1
> >> WARNING: mm/page_alloc.c:5280 at __alloc_frozen_pages_noprof+0x2ce/0x380 mm/page_alloc.c:5280, CPU#0: syz.0.0/5319
> >
> > Thanks.  drivers/usb/gadget is the offender.
> >
> > Gemini sums it up well.  "ep_write_iter() needs a bounds check prior to
> > memory allocation".  https://share.gemini.google/5NzjyttO0ULc
> >
> > I expect an easy fix would be
> 
> Maybe it is better to stop asking kmalloc for unreasonable len:
> 
> 
> diff --git a/drivers/usb/gadget/legacy/inode.c b/drivers/usb/gadget/legacy/inode.c
> index d87a8ab515107..20905f254968f 100644
> --- a/drivers/usb/gadget/legacy/inode.c
> +++ b/drivers/usb/gadget/legacy/inode.c
> @@ -645,6 +645,9 @@ ep_write_iter(struct kiocb *iocb, struct iov_iter *from)
>  	ssize_t value;
>  	char *buf;
>  
> +	if (len > KMALLOC_MAX_SIZE)
> +		return -EINVAL;

Is there any reason to think that KMALLOC_MAX_SIZE is a good limit?  The 
allocation could still fail, and you'd still get a WARNing.

I prefer Andrew's first suggestion.  If the user asks the kernel to copy 
too much data, just fail -- with no warning.

Alan Stern

^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2026-08-16 23:32 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-08-16 19:25 [syzbot] [mm?] WARNING in ep_write_iter syzbot
2026-08-16 20:52 ` Andrew Morton
2026-08-16 21:47   ` Zi Yan
2026-08-16 23:32     ` Alan Stern

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