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 AB4B52ED154; Tue, 25 Aug 2026 13:38:28 +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=1787665110; cv=none; b=N8CerlG7zN9dOKu0uKUzMcTQevkz53UIUBHRYvhegTbgw3YIzpkQ08JQhQqcAfRD/sN0ahvF9Lx6TXg7x4KZL+Q73pkZUxb3Ucg+s2SG1oKWM9pKkbfdik29KqcJDwlT/6CilmugriKaSAUh1/mjY+9sS7JguBXWaFs7F4P57EU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787665110; c=relaxed/simple; bh=dnUErF2KbCWgSqIiEA7VboWP4wkd1N0QoiEeraL7w9I=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hA39bwA9xNOVNZjkTe3f4p/d5Q8vC7hMao4EbawMANuBAI0PWl/Kf91ouqXZSo1IpnMd48xgsrb95ZM9ZcV2TsuWuQ1KkxydOtpU049E6Mh62SGwsQ/C1SH0WnCq+RZBp11dBOQwV2vEQjoNO9OAzU32tsaGxAMSpbPBaXi0GkM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0vmBa4gZ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="0vmBa4gZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0C38C1F000E9; Tue, 25 Aug 2026 13:38:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787665108; bh=K+N3E0puxeCzbCNoNsRAatzNualc/YoWub60zpZVgyc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=0vmBa4gZHbx/3Afp/XtSqSR0sbSqK/7C76kZBdRJlheyi19FZnAmd2LHZkLgMtxkM mmF3KwlFveuewQsXTxbkzvDOBDueJwR4hOLC8RMylpZKbBr4yC302ZXLtdOknLn+K4 9quMFAiwYlSqkmRBteERfB3R9EJThxbf2mVGbSg8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Peiyang He , Jason Gunthorpe Subject: [PATCH 6.18 11/94] iommu/iommufd: Fix NULL pointer deref in iommufd_ioas_change_process when racing with iopt_map_file_pages Date: Tue, 25 Aug 2026 15:25:07 +0200 Message-ID: <20260825132542.321910436@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260825132541.887883084@linuxfoundation.org> References: <20260825132541.887883084@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Peiyang He commit d616de490ec0242dcf78f02f1adf7baa035c4d0d upstream. iommufd_ioas_change_process() iterates every IOAS area while only holding every IOAS iova_rwsem, so it assumes every area has a non-NULL pages pointer. That assumption can be false when it runs concurrently with iopt_map_file_pages(). iopt_map_pages() executes in two phases. It first creates the area and inserts it into the interval tree under iova_rwsem, with area->pages still NULL. It then drops iova_rwsem and later fills area->pages under domains_rwsem. This leaves a window between area creation and area->pages fill where a concurrent iommufd_ioas_change_process() can observe the area and dereference a NULL area->pages pointer, leading to a NULL pointer dereference: BUG: kernel NULL pointer dereference, address: 00000000000000c0 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 4b655067 P4D 4b655067 PUD 0 Oops: Oops: 0000 [#1] SMP NOPTI CPU: 0 UID: 0 PID: 11841 Comm: syz.1.628 Not tainted 7.1.0 #3 PREEMPT(full) Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:iommufd_ioas_change_process+0x419/0xd50 drivers/iommu/iommufd/ioas.c:538 Code: 48 89 c3 48 85 c0 0f 84 cc 00 00 00 e8 10 f5 cb fd 48 8d 7b 68 e8 a7 b5 eb fd 48 8b 6b 68 48 8d bd c0 00 00 00 e8 17 b2 eb fd <8b> ad c0 00 00 00 bf 01 00 00 00 89 ee e8 85 ef cb fd 83 fd 01 74 RSP: 0018:ffffc90015c17d28 EFLAGS: 00010246 RAX: ffff8880186d5328 RBX: ffff88801d25e240 RCX: 0000000080000000 RDX: 00000000000002d7 RSI: ffffffff83ba9e10 RDI: 00000000000000c0 RBP: 0000000000000000 R08: ffffffff8e781eb8 R09: 0000000000000000 R10: 00000000000000c0 R11: ffffffff83ba9e29 R12: ffff88802e216008 R13: ffff88802e216000 R14: 0000000000000001 R15: 0000000000000000 FS: 00007f4aea3f66c0(0000) GS:ffff8880b1fa1000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000000000c0 CR3: 000000004b75c000 CR4: 0000000000350ef0 Call Trace: iommufd_fops_ioctl+0x287/0x400 drivers/iommu/iommufd/main.c:533 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+0x120/0x170 fs/ioctl.c:583 x64_sys_call+0x1092/0x1fb0 arch/x86/include/generated/asm/syscalls_64.h:17 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10a/0x680 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f4aec1a82bd Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 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 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f4aea3f6018 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f4aec436090 RCX: 00007f4aec1a82bd RDX: 0000200000000180 RSI: 0000000000003b92 RDI: 0000000000000003 RBP: 00007f4aec250295 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f4aec436128 R14: 00007f4aec436090 R15: 00007ffd04ef23e0 Modules linked in: CR2: 00000000000000c0 ---[ end trace 0000000000000000 ]--- RIP: 0010:iommufd_ioas_change_process+0x419/0xd50 drivers/iommu/iommufd/ioas.c:538 Code: 48 89 c3 48 85 c0 0f 84 cc 00 00 00 e8 10 f5 cb fd 48 8d 7b 68 e8 a7 b5 eb fd 48 8b 6b 68 48 8d bd c0 00 00 00 e8 17 b2 eb fd <8b> ad c0 00 00 00 bf 01 00 00 00 89 ee e8 85 ef cb fd 83 fd 01 74 RSP: 0018:ffffc90015c17d28 EFLAGS: 00010246 RAX: ffff8880186d5328 RBX: ffff88801d25e240 RCX: 0000000080000000 RDX: 00000000000002d7 RSI: ffffffff83ba9e10 RDI: 00000000000000c0 RBP: 0000000000000000 R08: ffffffff8e781eb8 R09: 0000000000000000 R10: 00000000000000c0 R11: ffffffff83ba9e29 R12: ffff88802e216008 R13: ffff88802e216000 R14: 0000000000000001 R15: 0000000000000000 FS: 00007f4aea3f66c0(0000) GS:ffff8880b1fa1000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000000000c0 CR3: 000000004b75c000 CR4: 0000000000350ef0 ---------------- Code disassembly (best guess): 0: 48 89 c3 mov %rax,%rbx 3: 48 85 c0 test %rax,%rax 6: 0f 84 cc 00 00 00 je 0xd8 c: e8 10 f5 cb fd call 0xfdcbf521 11: 48 8d 7b 68 lea 0x68(%rbx),%rdi 15: e8 a7 b5 eb fd call 0xfdebb5c1 1a: 48 8b 6b 68 mov 0x68(%rbx),%rbp 1e: 48 8d bd c0 00 00 00 lea 0xc0(%rbp),%rdi 25: e8 17 b2 eb fd call 0xfdebb241 * 2a: 8b ad c0 00 00 00 mov 0xc0(%rbp),%ebp <-- trapping instruction 30: bf 01 00 00 00 mov $0x1,%edi 35: 89 ee mov %ebp,%esi 37: e8 85 ef cb fd call 0xfdcbefc1 3c: 83 fd 01 cmp $0x1,%ebp 3f: 74 .byte 0x74 Fix by mirroring the handling logic in iopt_unmap_iova_range(), i.e. return -EBUSY if area->pages is NULL. Fixes: 829ed626499c ("iommufd: Add IOMMU_IOAS_CHANGE_PROCESS") Link: https://patch.msgid.link/r/7344B7A7B9957A65+20260806045059.1884737-1-peiyang_he@smail.nju.edu.cn Cc: stable@vger.kernel.org Signed-off-by: Peiyang He Signed-off-by: Jason Gunthorpe Signed-off-by: Greg Kroah-Hartman --- drivers/iommu/iommufd/ioas.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/drivers/iommu/iommufd/ioas.c +++ b/drivers/iommu/iommufd/ioas.c @@ -541,6 +541,10 @@ int iommufd_ioas_change_process(struct i return rc; for_each_ioas_area(&ioas_list, index, ioas, area) { + if (!area->pages) { + rc = -EBUSY; + goto out; + } if (area->pages->type != IOPT_ADDRESS_FILE) { rc = -EINVAL; goto out;