From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 674851A680A for ; Thu, 19 Mar 2026 05:46:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773899163; cv=none; b=nqLrdPB0PX/bc4cJmiySV6q5bCaIrLxoJbxInigGlSNlTpCb4hHoxq85/zLUMdBy+WH7A0I6bfn+UaZCkxms1jtcqdW99eKm6COsVvbtYC3m6ngvjQ1cpZlgPyRghCBwegalkLDjhIY+fQ57SCiB5rMm7Hm3+swGN3mDb/1FRvA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773899163; c=relaxed/simple; bh=3rlYRiZSQIwbTV2YgyEI1AsPMPI9LpI0pqEVU9EUyhk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=c53AgeXJDIbPf4BXDw5SjJei9u/9i+Ac+o14RHhN8SrYekHUsRfTeuviqee3F/R5N9y4MKOWQImY2TQpw4LWl9oxasc8LC13eRfn1QXX6tJNokgSoZpBK2tM98umw/rGY6IXAQFYW287pLRU6Osignf5FjnCU9VSfkEM7AHb6Eo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qpH2E1M0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="qpH2E1M0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9DB33C19425; Thu, 19 Mar 2026 05:45:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773899163; bh=3rlYRiZSQIwbTV2YgyEI1AsPMPI9LpI0pqEVU9EUyhk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qpH2E1M0hDRVkWkc6HN5OsZ9LRQwvROi0pn480R2jtbJxRw81caSggF/cYn5KvR3a 5M6NSMttg14QwG2/q7q7ffOAwTpfzKGDR5GHFWSfMV1aBBCNQSga9vp8VjBz3D6O+w RZLocMg+8pQi0GmbM2RveVjonvaBypwSUzeKBbF6tljvr1XljrBKe4vAjnDugsW1zK ss1I/JDGG+AB/gfWBcwX+6f3GOgQSUmGrhA+M2jvYuLBVF96NAWGXye9ZoMmXe3L15 eo/NV70c8CU60gh13KVCR9YtEbSIzigsKRJEIGnCfj21L2qaJ7dzBR5sz2/XjcR1bn HNn8L3TqPu6Mg== Date: Thu, 19 Mar 2026 07:45:53 +0200 From: Mike Rapoport To: "Lorenzo Stoakes (Oracle)" Cc: syzbot , Liam.Howlett@oracle.com, akpm@linux-foundation.org, baohua@kernel.org, baolin.wang@linux.alibaba.com, david@kernel.org, dev.jain@arm.com, lance.yang@linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, npache@redhat.com, ryan.roberts@arm.com, syzkaller-bugs@googlegroups.com, ziy@nvidia.com, Harry Yoo Subject: Re: [syzbot] [mm?] general protection fault in zap_huge_pmd Message-ID: References: <69babeba.050a0220.1b2d94.0003.GAE@google.com> <6b3d7ad7-49e1-407a-903d-3103704160d8@lucifer.local> 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-Disposition: inline In-Reply-To: <6b3d7ad7-49e1-407a-903d-3103704160d8@lucifer.local> On Wed, Mar 18, 2026 at 05:26:32PM +0000, Lorenzo Stoakes (Oracle) wrote: > +cc Mike for uffd, Harry for fix that also resolves this, see below > > On Wed, Mar 18, 2026 at 08:03:22AM -0700, syzbot wrote: > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: b84a0ebe421c Add linux-next specific files for 20260313 > > For some reason I have to git pull --tags to get this... commit hash locally? > Strange. > > > git tree: linux-next > > console output: https://syzkaller.appspot.com/x/log.txt?x=119ddd52580000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=e7280ad1f68b2dce > > dashboard link: https://syzkaller.appspot.com/bug?extid=de14f7701c22477db718 > > compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=173b44da580000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1537b8da580000 > > @SYZKALLER guys: > > Note: the repro is incorrectly labelling; > > // ioctl$UFFDIO_CONTINUE arguments: [ > // fd: fd_uffd (resource) > // cmd: const = 0xc020aa08 (4 bytes) > > as UFFDIO_CONTINUE (0x7), it's actually UFFDIO_POISION (0x8) as you can see > from least-significant byte. > > It's also stating things like mmap flags wrong e.g.: > > /*flags=MAP_UNINITIALIZED|MAP_POPULATE|MAP_NORESERVE|MAP_NONBLOCK|MAP_HUGETLB|0x8c4b815a506002b2*/ > 0x8c4b815a5465c2b2ul, As Andrey Vagin pointed off-list, you can run strace repro and see the syscall arguments quite nicely :-) > So Harry's fix resolves this, and that's the important bit ;-P > but we should handle this case better in zap_huge_pmd(), I will send a > patch for that. > Cheers, Lorenzo -- Sincerely yours, Mike.