From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5A6041A6817; Sun, 16 Aug 2026 20:52:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786913524; cv=none; b=Ly1xT78OCfnKiNPmPH1S8+oPyHo77OIneScN0lRrEE5XSFmEnFK39elwQZdiRzpayxlCOp/GONw5/iItNYx+MHQC8OJ8s03H50IBn33HlKbWWPY91cIeuzO/xfvboUa0wb4rPFY+H6FrNg/v7PjCl0xBLUWygJMurM7pyTeENi4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786913524; c=relaxed/simple; bh=XWl8vrkeIkHkmZDaOCpDMhV767drm24ZRB5NOelD/h4=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=hr55nIaTzXZbl4WR7AAILmR/gWi4ADftKN+nlu+SnEqbgiDmlQa4spg3H8QqzFwwfwoot2vwellaZlsrFzFngbnPHrggfCaRmKZ720KOHmYQlnak9ySMQcOcNfwS6KqaLzBF7fn0dJZVX2l0X1O0Fkew3lOCQOM4AzObj4evTRQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=rCRTxcPi; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="rCRTxcPi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 636621F000E9; Sun, 16 Aug 2026 20:52:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1786913522; bh=i48aE4Uvnr3uPhEqoogP6eiRnIdhnmoP8F6HN4onxrM=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=rCRTxcPiTLmV5+++k9RQBwTNllVru5d4JrirhyxKohl0jrFNIpwYmWVZdIVSofkCg wolLGHMByhAw+zhL+2YJTeslbimvKcK58vufmJijyM71rPf2jvvdnQ7PyjwYgPiJNY CR21TPDCYS99/4vbCEFCw3ydOqGZ5XGb1h5h3Ngc= Date: Sun, 16 Aug 2026 13:52:01 -0700 From: Andrew Morton To: syzbot Cc: apopple@nvidia.com, byungchul@sk.com, david@kernel.org, gourry@gourry.net, joshua.hahnjy@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, matthew.brost@intel.com, rakie.kim@sk.com, syzkaller-bugs@googlegroups.com, ying.huang@linux.alibaba.com, ziy@nvidia.com, Greg Kroah-Hartman , linux-usb@vger.kernel.org Subject: Re: [syzbot] [mm?] WARNING in ep_write_iter Message-Id: <20260816135201.98590b17b526dda8c4ec9105@linux-foundation.org> In-Reply-To: <6a820ebc.9ebadd4d.20b15e.001b.GAE@google.com> References: <6a820ebc.9ebadd4d.20b15e.001b.GAE@google.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sun, 16 Aug 2026 12:25:48 -0700 syzbot 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: > > 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 > >